PilotHandbook

pilot with an effective safeguard against disorientation in the “A” and “B” Signal
event of radio malfunction. Received

There are four radio navigation systems available for use for Only “A” Signal Received Only “B” Signal Received
VFR navigation. These are:
Neither “A” nor “B”
• VHF Omnidirectional Range (VOR) Signal Received
• Nondirectional Radio Beacon (NDB)
• Long Range Navigation (LORAN-C)
• Global Positioning System (GPS)

Very High Frequency (VHF) Omnidirectional VOR VOR
Range (VOR) Station Station
The VOR system is present in three slightly different
navigation aids (NAVAIDs): VOR, VOR/DME, and “A” “B”
VORTAC. By itself it is known as a VOR, and it provides
magnetic bearing information to and from the station. When Figure 15-28. VHF transmissions follow a line-of-sight course.
DME is also installed with a VOR, the NAVAID is referred
to as a VOR/DME. When military tactical air navigation VORs and VORTACs are classed according to operational
(TACAN) equipment is installed with a VOR, the NAVAID use. There are three classes:
is known as a VORTAC. DME is always an integral part of a
VORTAC. Regardless of the type of NAVAID utilized (VOR, • T (Terminal)
VOR/DME or VORTAC), the VOR indicator behaves the • L (Low altitude)
same. Unless otherwise noted, in this section, VOR, VOR/ • H (High altitude)
DME and VORTAC NAVAIDs are all referred to hereafter
as VORs. The normal useful range for the various classes is shown in
the following table:
The prefix “omni-” means all, and an omnidirectional range
is a VHF radio transmitting ground station that projects VOR/VORTAC NAVAIDS
straight line courses (radials) from the station in all directions. Normal Usable Altitudes and Radius Distances
From a top view, it can be visualized as being similar to
the spokes from the hub of a wheel. The distance VOR
radials are projected depends upon the power output of the
transmitter.

The course or radials projected from the station are referenced Distance
to magnetic north. Therefore, a radial is defined as a line of
magnetic bearing extending outward from the VOR station. Class Altitudes (Miles)
Radials are identified by numbers beginning with 001, T
which is 1° east of magnetic north, and progress in sequence L 12,000' and below 25
through all the degrees of a circle until reaching 360. To aid H
in orientation, a compass rose reference to magnetic north is H Below 18,000' 40
superimposed on aeronautical charts at the station location.
H Below 14,500' 40
VOR ground stations transmit within a VHF frequency band H
of 108.0–117.95 MHz. Because the equipment is VHF, the Within the conterminous 48 states
signals transmitted are subject to line-of-sight restrictions.
Therefore, its range varies in direct proportion to the altitude only, between 14,500 and 17,999' 100
of receiving equipment. Generally, the reception range of
the signals at an altitude of 1,000 feet above ground level 18,000'—FL 450 130
(AGL) is about 40 to 45 miles. This distance increases with
altitude. [Figure 15-28] 60,000'—FL 450 100

The useful range of certain facilities may be less than 50 miles.
For further information concerning these restrictions, refer to
the Communication/NAVAID Remarks in the A/FD.

15-22

The accuracy of course alignment of VOR radials is receiving equipment. The ground transmitter is located at a
considered to be excellent. It is generally within plus or specific position on the ground and transmits on an assigned
minus 1°. However, certain parts of the VOR receiver frequency. The aircraft equipment includes a receiver with
equipment deteriorate, and this affects its accuracy. This is a tuning device and a VOR or omninavigation instrument.
particularly true at great distances from the VOR station. The The navigation instrument could be a course deviation
best assurance of maintaining an accurate VOR receiver is indicator (CDI), horizontal situation indicator (HSI), or a
periodic checks and calibrations. VOR accuracy checks are radio magnetic indicator (RMI). Each of these instruments
not a regulatory requirement for VFR flight. However, to indicates the course to the tuned VOR.
assure accuracy of the equipment, these checks should be
accomplished quite frequently and a complete calibration Course Deviation Indicator (CDI)
each year. The following means are provided for pilots to The CDI is found in most training aircraft. It consists of
check VOR accuracy: (1) omnibearing selector (OBS) sometimes referred to as
the course selector, (2) a CDI needle (Left-Right Needle),
• FAA VOR test facility (VOT) and (3) a TO/FROM indicator.

• Certified airborne checkpoints The course selector is an azimuth dial that can be rotated to
select a desired radial or to determine the radial over which
• Certified ground checkpoints located on airport the aircraft is flying. In addition, the magnetic course “TO”
surfaces or “FROM” the station can be determined.

If an aircraft has two VOR receivers installed, a dual VOR When the course selector is rotated, it moves the CDI or
receiver check can be made. To accomplish the dual receiver needle to indicate the position of the radial relative to the
check, a pilot tunes both VOR receivers to the same VOR aircraft. If the course selector is rotated until the deviation
ground facility. The maximum permissible variation between needle is centered, the radial (magnetic course “FROM” the
the two indicated bearings is 4 degrees. A list of the airborne station) or its reciprocal (magnetic course “TO” the station)
and ground checkpoints is published in the A/FD. can be determined. The course deviation needle also moves
to the right or left if the aircraft is flown or drifting away
Basically, these checks consist of verifying that the VOR from the radial which is set in the course selector.
radials the aircraft equipment receives are aligned with the
radials the station transmits. There are not specific tolerances By centering the needle, the course selector indicates either
in VOR checks required for VFR flight. But as a guide to the course “FROM” the station or the course “TO” the station.
assure acceptable accuracy, the required IFR tolerances can If the flag displays a “TO,” the course shown on the course
be used—±4° for ground checks and ±6° for airborne checks. selector must be flown to the station. [Figure 15-29] If
These checks can be performed by the pilot.
Course index N 3
The VOR transmitting station can be positively identified
by its Morse code identification or by a recorded voice 33 Unreliable signal flag
identification which states the name of the station followed
by “VOR.” Many FSS transmit voice messages on the same 24 W 30 N TO 6 E 12
frequency that the VOR operates. Voice transmissions should AV
not be relied upon to identify stations, because many FSS CDI needle
remotely transmit over several omniranges, which have
names different from that of the transmitting FSS. If the VOR Approximately 2 degrees TO/FROM indicator
is out of service for maintenance, the coded identification is in the VOR mode
removed and not transmitted. This serves to alert pilots that
this station should not be used for navigation. VOR receivers OBS S 21 15
are designed with an alarm flag to indicate when signal
strength is inadequate to operate the navigational equipment.
This happens if the aircraft is too far from the VOR or the
aircraft is too low and, therefore, is out of the line of sight
of the transmitting signals.

Using the VOR OBS knob
Figure 15-29. VOR indicator.
In review, for VOR radio navigation, there are two
components required: ground transmitter and aircraft

15-23

“FROM” is displayed and the course shown is followed, the in the same manner, the angular movement of a conventional

aircraft is flown away from the station. VOR/LOC needle indicates deviation from course.

Horizontal Situation Indicator The desired course is selected by rotating the course select
The HSI is a direction indicator that uses the output pointer, in relation to the compass card, by means of the
from a flux valve to drive the compass card. The HSI course select knob. The HSI has a fixed aircraft symbol
[Figure 15-30] combines the magnetic compass with and the course deviation bar displays the aircraft’s position
navigation signals and a glideslope. The HSI gives the pilot relative to the selected course. The TO/FROM indicator is a
an indication of the location of the aircraft with relationship triangular pointer. When the indicator points to the head of
to the chosen course or radial. the course select pointer, the arrow shows the course selected.
If properly intercepted and flown, the course will take the
In Figure 15-30, the aircraft magnetic heading displayed aircraft to the chosen facility. When the indicator points to the
on the compass card under the lubber line is 184°. The tail of the course, the arrow shows that the course selected, if
course select pointer shown is set to 295°; the tail of the properly intercepted and flown, will take the aircraft directly
pointer indicates the reciprocal, 115°. The course deviation away from the chosen facility.
bar operates with a VOR/Localizer (VOR/LOC) or GPS
navigation receiver to indicate left or right deviations from When the NAV warning flag appears it indicates no reliable
the course selected with the course select pointer; operating signal is being received. The appearance of the HDG flag
indicates the compass card is not functioning properly.

To/From indicator Glideslope deviation scale The glideslope pointer indicates the relation of the aircraft to
Compass card Course deviation scale the glideslope. When the pointer is below the center position,
NAV warning flag Compass warning flag the aircraft is above the glideslope and an increased rate
Lubber line of descent is required. In some installations, the azimuth
card is a remote indicating compass; however, in others the
heading must be checked occasionally against the magnetic
compass and reset.

DC Radio Magnetic Indicator (RMI)
The RMI [Figure 15-31] is a navigational aid providing
GS I5 2I GS aircraft magnetic or directional gyro heading and very high
NAV frequency omnidirectional range (VOR), GPS, and automatic
HDG direction finder (ADF) bearing information. Remote indicating
24 W 30

24 30
6 I2 33 3 HDG15 S 21

6 E 12
Course select knob FAD FAD

Symbolic aircraft Course deviation bar NAV NAV33 N 3

Heading select bug Course select pointer Figure 15-31. Radio magnetic indicator.

Dual glideslope pointers Heading select knob

Figure 15-30. Horizontal situation indicator.
15-24

compasses were developed to compensate for errors in and 7 24 W 30 33 N 3 33 3
limitations of older types of heading indicators. 24 30
33 3 FROM 6 I2
The remote compass transmitter is a separate unit usually OBS 6 E 12
mounted in a wingtip to eliminate the possibility of magnetic I5 2I
interference. The RMI consists of a compass card, a heading S 21 15 N
index, two bearing pointers, and pointer function switches. 1. View
The two pointers are driven by any two combinations of a 24 30 6 I2 8
GPS, an ADF, and/or a VOR. The pilot has the ability to posi
select the navigation aid to be indicated. The pointer indicates I5 2I 36 2. Mov
course to selected NAVAID or waypoint. In Figure 15-31
the green pointer is indicating the station tuned on the ADF. 24 W 30 33 N 3 rese
The yellow pointer is indicating the course to a VOR of turn
GPS waypoint. Note that there is no requirement for a pilot FROM
to select course with the RMI, but only the NAVAID is to OBS 6 E 12 6 30 33 I2 I5
be indicated.
33 3S 21 15 0 21 24
18 S
3 6
N 2I 24

27 30 33 12 15
6 W E

24 30 6 I2 FROM
OBS
I5 2I

Tracking With VOR 24 W 30 33 N 3 6 E 12 5
The following describes a step-by-step procedure to use when
tracking to and from a VOR station using a CDI. Figure 15-32 TO
illustrates the procedure.
OBS
S 21 15

First, tune the VOR receiver to the frequency of the selected 24 W 30 33 N 3 6 I224 3033 3 WIND
VOR station. For example, 115.0 to receive Bravo VOR. Next, 6 E 12 33 3
check the identifiers to verify that the desired VOR is being TO I5 2I 4
received. As soon as the VOR is properly tuned, the course S 21 15 3
deviation needle deflects either left or right. Then, rotate the OBS
azimuth dial to the course selector until the course deviation 24 W 30 6 I224 30
needle centers and the TO-FROM indicator indicates “TO.” 33 N 3 6 E 12
If the needle centers with a “FROM” indication, the azimuth I5 2I
should be rotated 180° because, in this case, it is desired to TOS 2115
fly “TO” the station. Now, turn the aircraft to the heading
indicated on the VOR azimuth dial or course selector, 350° OBS
in this example.
36
30 33

2I 24 I2 I5 BRAVO

If a heading of 350° is maintained with a wind from the right 33 N 3 2 BRA 115.0
as shown, the aircraft drifts to the left of the intended track.
As the aircraft drifts off course, the VOR course deviation 24 W 30 TO 6 E 12
needle gradually moves to the right of center or indicates the
direction of the desired radial or track. OBS
S 21 15

To return to the desired radial, the aircraft heading must be 24 W 30 33 N 3 24 30 33 3 1
altered to the right. As the aircraft returns to the desired track,
the deviation needle slowly returns to center. When centered, TO
the aircraft is on the desired radial and a left turn must be
made toward, but not to the original heading of 350° because 6 I2
a wind drift correction must be established. The amount of 6 E 12
correction depends upon the strength of the wind. If the wind I5 2I
velocity is unknown, a trial-and-error method can be used S 21 15
to find the correct heading. Assume, for this example, a 10° OBS
correction for a heading of 360° is maintained.
Figure 15-32. Tracking a radial in a crosswind.

15-25

While maintaining a heading of 360°, assume that the course deviation needle is reversed. To further explain this
deviation begins to move to the left. This means that the wind reverse action, if the aircraft is flown toward a station
correction of 10° is too great and the aircraft is flying to the with a “FROM” indication or away from a station
right of course. A slight turn to the left should be made to with a “TO” indication, the course deviation needle
permit the aircraft to return to the desired radial. indicates in an direction opposite to that which it
should indicate. For example, if the aircraft drifts to
When the deviation needle centers, a small wind drift the right of a radial being flown, the needle moves to
correction of 5° or a heading correction of 355° should be the right or points away from the radial. If the aircraft
flown. If this correction is adequate, the aircraft remains drifts to the left of the radial being flown, the needle
on the radial. If not, small variations in heading should be moves left or in the direction opposite to the radial.
made to keep the needle centered, and consequently keep the
aircraft on the radial. • When navigating using the VOR it is important to fly
headings that maintain or re-intercept the course. Just
As the VOR station is passed, the course deviation needle turning toward the needle will cause overshooting
fluctuates, then settles down, and the “TO” indication the radial and flying an S turn to the left and right of
changes to “FROM.” If the aircraft passes to one side of the course.
station, the needle deflects in the direction of the station as
the indicator changes to “FROM.” Time and Distance Check From a Station
To compute time and distance from a station, first turn the
Generally, the same techniques apply when tracking aircraft to place the bearing pointer on the nearest 90° index.
outbound as those used for tracking inbound. If the intent is Note time and maintain heading. When the bearing pointer
to fly over the station and track outbound on the reciprocal of has moved 10°, note the elapsed time in seconds and apply
the inbound radial, the course selector should not be changed. the formulas in the following example to determine time and
Corrections are made in the same manner to keep the needle distance. [Figure 15-33]
centered. The only difference is that the omnidirectional
range indicator indicates “FROM.” Time-Distance Check Example

If tracking outbound on a course other than the reciprocal of Time in seconds between bearings = Minutes to station
the inbound radial, this new course or radial must be set in Degrees of bearing change
the course selector and a turn made to intercept this course.
After this course is reached, tracking procedures are the same For example, if 2 minutes (120 seconds) is required to fly a
as previously discussed. bearing change of 10 degrees, the aircraft is—

Tips on Using the VOR 120 = 12 minutes to the station
10
• Positively identify the station by its code or voice
identification. Figure 15-33. Time-distance check example.

• Keep in mind that VOR signals are “line-of-sight.” A The time from station may also be calculated by using a short
weak signal or no signal at all is received if the aircraft method based on the above formula, if a 10° bearing change
is too low or too far from the station. is flown. If the elapsed time for the bearing change is noted
in seconds and a 10° bearing change is made, the time from
• When navigating to a station, determine the inbound the station in minutes is determined by counting off one
radial and use this radial. Fly a heading that will decimal point. Thus, if 75 seconds are required to fly a 10°
maintain the course. If the aircraft drifts, fly a heading bearing change, the aircraft is 7.5 minutes from the station.
to re-intercept the course then apply a correction to When the bearing pointer is moving rapidly or when several
compensate for wind drift. corrections are required to place the pointer on the wingtip
position, the aircraft is at station passage.
• If minor needle fluctuations occur, avoid changing
headings immediately. Wait momentarily to see if the The distance from the station is computed by multiplying TAS
needle recenters; if it does not, then correct. or GS (in miles per minute) by the previously determined time
in minutes. For example, if the aircraft is 7.5 minutes from
• When flying “TO” a station, always fly the selected station, flying at a TAS of 120 knots or 2 NM per minute, the
course with a “TO” indication. When flying “FROM” a distance from station is 15 NM (7.5 x 2 = 15).
station, always fly the selected course with a “FROM”
indication. If this is not done, the action of the course

15-26

The preceding are methods of computing approximate time referred to as a VORTAC). Although DME equipment is very
and distance. The accuracy of time and distance checks is popular, not all aircraft are DME equipped.
governed by existing wind, degree of bearing change, and
accuracy of timing. The number of variables involved causes To utilize DME, the pilot should select, tune, and identify
the result to be only an approximation. However, by flying an a VORTAC, as previously described. The DME receiver,
accurate heading and checking the time and bearing closely, utilizing what is called a “paired frequency” concept,
the pilot can make a reasonable estimate of time and distance automatically selects and tunes the UHF DME frequency
from the station. associated with the VHF VORTAC frequency selected by
the pilot. This process is entirely transparent to the pilot.
Course Intercept After a brief pause, the DME display shows the slant range
Course interceptions are performed in most phases of distance to or from the VORTAC. Slant range distance is the
instrument navigation. The equipment used varies, but an direct distance between the aircraft and the VORTAC, and
intercept heading must be flown that results in an angle or is therefore affected by aircraft altitude. (Station passage
rate of intercept sufficient to solve a particular problem. directly over a VORTAC from an altitude of 6,076 feet above
ground level (AGL) would show approximately 1.0 NM on
Rate of Intercept the DME.) DME is a very useful adjunct to VOR navigation.
Rate of intercept, seen by the aviator as bearing pointer or A VOR radial alone merely gives line of position information.
HSI movement, is a result of the following factors: With DME, a pilot may precisely locate the aircraft on that
line (radial).
• The angle at which the aircraft is flown toward a
desired course (angle of intercept) Most DME receivers also provide GS and time-to-station
modes of operation. The GS is displayed in knots (NMPH).
• True airspeed and wind (GS) The time-to-station mode displays the minutes remaining to
VORTAC station passage, predicated upon the present GS.
• Distance from the station GS and time-to-station information is only accurate when
tracking directly to or from a VORTAC. DME receivers
Angle of Intercept typically need a minute or two of stabilized flight directly to
The angle of intercept is the angle between the heading of the or from a VORTAC before displaying accurate GS or time-
aircraft (intercept heading) and desired course. Controlling to-station information.
this angle by selection/adjustment of the intercept heading
is the easiest and most effective way to control course Some DME installations have a hold feature that permits
interceptions. Angle of intercept must be greater than the a DME signal to be retained from one VORTAC while the
degrees from course, but should not exceed 90°. Within this course indicator displays course deviation information from
limit, adjust to achieve the most desirable rate of intercept. an ILS or another VORTAC.

When selecting an intercept heading, the key factor is the VOR/DME RNAV
relationship between distance from the station and degrees Area navigation (RNAV) permits electronic course guidance
from the course. Each degree, or radial, is 1 NM wide at on any direct route between points established by the pilot.
a distance of 60 NM from the station. Width increases or While RNAV is a generic term that applies to a variety of
decreases in proportion to the 60 NM distance. For example, navigational aids, such as LORAN-C, GPS, and others, this
1 degree is 2 NM wide at 120 NM—and ½ NM wide at 30 section deals with VOR/DME-based RNAV. VOR/DME
NM. For a given GS and angle of intercept, the resultant rate RNAV is not a separate ground-based NAVAID, but a
of intercept varies according to the distance from the station. method of navigation using VOR/DME and VORTAC
When selecting an intercept heading to form an angle of signals specially processed by the aircraft’s RNAV computer.
intercept, consider the following factors: [Figure 15-34]

• Degrees from course NOTE: In this section, the term “VORTAC” also includes
VOR/DME NAVAIDs.
• Distance from the station
In its simplest form, VOR/DME RNAV allows the pilot to
• True airspeed and wind (GS) electronically move VORTACs around to more convenient
locations. Once electronically relocated, they are referred
Distance Measuring Equipment (DME) to as waypoints. These waypoints are described as a
Distance measuring equipment (DME) consists of an ultra
high frequency (UHF) navigational aid with VOR/DMEs and
VORTACs. It measures, in NM, the slant range distance of
an aircraft from a VOR/DME or VORTAC (both hereafter

15-27

Area Navigation Direct Route a course. To operate in any RNAV mode, the unit needs
both radial and distance signals; therefore, a VORTAC (or
Figure 15-34. Flying an RNAV course. VOR/DME) needs to be selected as a NAVAID. To establish
a waypoint, a point somewhere within the service range of
combination of a selected radial and distance within the a VORTAC is defined on the basis of radial and distance.
service volume of the VORTAC to be used. These waypoints Once the waypoint is entered into the unit and the RNAV en
allow a straight course to be flown between almost any route mode is selected, the CDI displays course guidance to
origin and destination, without regard to the orientation of the waypoint, not the original VORTAC. DME also displays
VORTACs or the existence of airways. distance to the waypoint. Many units have the capability to
store several waypoints, allowing them to be programmed
While the capabilities and methods of operation of VOR/ prior to flight, if desired, and called up in flight.
DME RNAV units differ, there are basic principles of
operation that are common to all. Pilots are urged to study RNAV waypoints are entered into the unit in magnetic
the manufacturer’s operating guide and receive instruction bearings (radials) of degrees and tenths (i.e., 275.5°) and
prior to the use of VOR/DME RNAV or any unfamiliar distances in NM and tenths (i.e., 25.2 NM). When plotting
navigational system. Operational information and limitations RNAV waypoints on an aeronautical chart, pilots find it
should also be sought from placards and the supplement difficult to measure to that level of accuracy, and in practical
section of the AFM/POH. application, it is rarely necessary. A number of flight planning
publications publish airport coordinates and waypoints with
VOR/DME-based RNAV units operate in at least three this precision and the unit accepts those figures. There is a
modes: VOR, en route, and approach. A fourth mode, VOR subtle, but important difference in CDI operation and display
Parallel, may also be found on some models. The units need in the RNAV modes.
both VOR and DME signals to operate in any RNAV mode.
If the NAVAID selected is a VOR without DME, RNAV In the RNAV modes, course deviation is displayed in terms
mode will not function. of linear deviation. In the RNAV en route mode, maximum
deflection of the CDI typically represents 5 NM on either side
In the VOR (or non-RNAV) mode, the unit simply functions of the selected course, without regard to distance from the
as a VOR receiver with DME capability. [Figure 15-35] The waypoint. In the RNAV approach mode, maximum deflection
unit’s display on the VOR indicator is conventional in all of the CDI typically represents 1¼ NM on either side of the
respects. For operation on established airways or any other selected course. There is no increase in CDI sensitivity as the
ordinary VOR navigation, the VOR mode is used. aircraft approaches a waypoint in RNAV mode.

The RNAV approach mode is used for instrument approaches.
Its narrow scale width (¼ of the en route mode) permits very
precise tracking to or from the selected waypoint. In visual
flight rules (VFR) cross-country navigation, tracking a course
in the approach mode is not desirable because it requires a
great deal of attention and soon becomes tedious.

OFFSET 33 EN ROUTE A fourth, lesser-used mode on some units is the VOR Parallel
mode. This permits the CDI to display linear (not angular)
R BEARING LOAD DISTANCE deviation as the aircraft tracks to and from VORTACs.
N It derives its name from permitting the pilot to offset (or
A parallel) a selected course or airway at a fixed distance of
V the pilot’s choosing, if desired. The VOR parallel mode
3 3 4 4 4 279 has the same effect as placing a waypoint directly over an
8 8 existing VORTAC. Some pilots select the VOR parallel
mode when utilizing the navigation (NAV) tracking function
12 12 of their autopilot for smoother course following near the
VORTAC.
Figure 15-35. RNAV controls.

To utilize the unit’s RNAV capability, the pilot selects and Confusion is possible when navigating an aircraft with VOR/
establishes a waypoint or a series of waypoints to define DME-based RNAV, and it is essential that the pilot become

15-28

familiar with the equipment installed. It is not unknown for One of the disadvantages that should be considered when
pilots to operate inadvertently in one of the RNAV modes using low frequency (LF) for navigation is that low frequency
when the operation was not intended by overlooking switch signals are very susceptible to electrical disturbances, such as
positions or annunciators. The reverse has also occurred with lightning. These disturbances create excessive static, needle
a pilot neglecting to place the unit into one of the RNAV deviations, and signal fades. There may be interference from
modes by overlooking switch positions or annunciators. distant stations. Pilots should know the conditions under
As always, the prudent pilot is not only familiar with the which these disturbances can occur so they can be more alert
equipment used, but never places complete reliance in just to possible interference when using the ADF.
one method of navigation when others are available for
cross-check. Basically, the ADF aircraft equipment consists of a tuner,
which is used to set the desired station frequency, and the
Automatic Direction Finder (ADF) navigational display.
Many general aviation-type aircraft are equipped with ADF
radio receiving equipment. To navigate using the ADF, the The navigational display consists of a dial upon which the
pilot tunes the receiving equipment to a ground station known azimuth is printed, and a needle which rotates around the dial
as a nondirectional radio beacon (NDB). The NDB stations and points to the station to which the receiver is tuned.
normally operate in a low or medium frequency band of
200 to 415 kHz. The frequencies are readily available on Some of the ADF dials can be rotated to align the
aeronautical charts or in the A/FD. azimuth with the aircraft heading; others are fixed with 0°
representing the nose of the aircraft, and 180° representing
All radio beacons except compass locators transmit a the tail. Only the fixed azimuth dial is discussed in this
continuous three-letter identification in code except during handbook. [Figure 15-36]
voice transmissions. A compass locator, which is associated
with an instrument landing system, transmits a two-letter
identification.

Standard broadcast stations can also be used in conjunction N-SN 36
with ADF. Positive identification of all radio stations is E-W E
extremely important and this is particularly true when using
standard broadcast stations for navigation. 33 12 15 S

NDBs have one advantage over the VOR. This advantage is 30
that low or medium frequencies are not affected by line-of-
sight. The signals follow the curvature of the Earth; therefore, 21 24 W
if the aircraft is within the range of the station, the signals
can be received regardless of altitude.

The following table gives the class of NDB stations, their
power, and usable range:

NONDIRECTIONAL RADIOBEACON (NDB) Figure 15-36. ADF with fixed azimuth and magnetic compass.
(Usable Radius Distances for All Altitudes)

Class Power Distance Figure 15-37 illustrates terms that are used with the ADF
Compass Locator (Watts) (Miles) and should be understood by the pilot.
MH Under 25 15
H Under 50 To determine the magnetic bearing “FROM” the station,
HH 50–1999 25 180° is added to or subtracted from the magnetic bearing to
2000 or more *50 the station. This is the reciprocal bearing and is used when
plotting position fixes.
75

*Service range of individual facilities may be less than 50
miles.

15-29

MagneMagnetic Northtic E 12 15N3 6
Magnetic heading
30 33 NbeaRreinlagtivtoe 330°W 30 33

N-S21 24 W 3 station S 21 24
E-W bearing S 21 24
6
E

12 15 S

Radio station

Figure 15-37. ADF terms. E 12 15

Keep in mind that the needle of fixed azimuth points to the 330°
station in relation to the nose of the aircraft. If the needle is N3 6W 30 33
deflected 30° to the left for a relative bearing of 330°, this
means that the station is located 30° left. If the aircraft is Figure 15-38. ADF tracking. 340° bearing to station
turned left 30°, the needle moves to the right 30° and indicates Although the ADF is not as popular as the VOR for radio
a relative bearing of 0°, or the aircraft is pointing toward navigation, with proper precautions and intelligent use, the
the station. If the pilot continues flight toward the station ADF can be a valuable aid to navigation.
keeping the needle on 0°, the procedure is called homing to Loran-C Navigation
the station. If a crosswind exists, the ADF needle continues to Long range navigation, version C (LORAN-C) is another
drift away from zero. To keep the needle on zero, the aircraft form of RNAV, but one that operates from chains of
must be turned slightly resulting in a curved flightpath to the transmitters broadcasting signals in the LF spectrum. World
station. Homing to the station is a common procedure, but Aeronautical Chart (WAC), sectional charts, and VFR
results in drifting downwind, thus lengthening the distance terminal area charts do not show the presence of LORAN-
to the station. C transmitters. Selection of a transmitter chain is either
made automatically by the unit, or manually by the pilot
Tracking to the station requires correcting for wind drift and using guidance information provided by the manufacturer.
results in maintaining flight along a straight track or bearing LORAN-C is a highly accurate, supplemental form of
to the station. When the wind drift correction is established, navigation typically installed as an adjunct to VOR and
the ADF needle indicates the amount of correction to the ADF equipment. Databases of airports, NAVAIDs, and ATC
right or left. For instance, if the magnetic bearing to the facilities are frequently features of LORAN-C receivers.
station is 340°, a correction for a left crosswind would
result in a magnetic heading of 330°, and the ADF needle
would indicate 10° to the right or a relative bearing of 010°.
[Figure 15-38]

When tracking away from the station, wind corrections are
made similar to tracking to the station, but the ADF needle
points toward the tail of the aircraft or the 180° position on
the azimuth dial. Attempting to keep the ADF needle on
the 180° position during winds results in the aircraft flying
a curved flight leading further and further from the desired
track. To correct for wind when tracking outbound, correction
should be made in the direction opposite of that in which the
needle is pointing.

15-30

LORAN-C is an outgrowth of the original LORAN-A during the process, such as verification or acknowledgment
developed for navigation during World War II. The LORAN-C of the information displayed.
system is used extensively in maritime applications. It
experienced a dramatic growth in popularity with pilots with Most units contain databases of navigational information.
the advent of the small, panel-mounted LORAN-C receivers Frequently, such databases contain not only airport and
available at relatively low cost. These units are frequently NAVAID locations, but also extensive airport, airspace, and
very sophisticated and capable, with a wide variety of ATC information. While the unit can operate with an expired
navigational functions. database, the information should be current or verified to be
correct prior to use. The pilot can update some databases,
With high levels of LORAN-C sophistication and capability, while others require removal from the aircraft and the services
a certain complexity in operation is an unfortunate necessity. of an avionics technician.
Pilots are urged to read the operating handbooks and to
consult the supplements section of the AFM/POH prior to VFR navigation with LORAN-C can be as simple as telling
utilizing LORAN-C for navigation. Many units offer so many the unit where the pilot wishes to go. The course guidance
features that the manufacturers often publish two different provided is a great circle (shortest distance) route to the
sets of instructions: (1) a brief operating guide and (2) in- destination. Older units may need a destination entered in
depth operating manual. terms of latitude and longitude, but recent designs need only
the identifier of the airport or NAVAID. The unit also permits
While coverage is not global, LORAN-C signals are suitable database storage and retrieval of pilot defined waypoints.
for navigation in all of the conterminous United States, and LORAN-C signals follow the curvature of the Earth and are
parts of Canada and Alaska. Several foreign countries also generally usable hundreds of miles from their transmitters.
operate their own LORAN-C systems. In the United States,
the U.S. Coast Guard operates the LORAN-C system. The LORAN-C signal is subject to degradation from a
LORAN-C system status is available from: USCG Navigation variety of atmospheric disturbances. It is also susceptible to
Center, Alexandria, Virginia at (703) 313-5900. interference from static electricity buildup on the airframe
and electrically “noisy” airframe equipment. Flight in
LORAN-C absolute accuracy is excellent—position errors precipitation or even dust clouds can cause occasional
are typically less than .25 NM. Repeatable accuracy, or interference with navigational guidance from LORAN-C
the ability to return to a waypoint previously visited, is signals. To minimize these effects, static wicks and bonding
even better. While LORAN-C is a form of RNAV, it differs straps should be installed and properly maintained.
significantly from VOR/DME-based RNAV. It operates in a
90–110 kHz frequency range and is based upon measurement LORAN-C navigation information is presented to the pilot in
of the difference in arrival times of pulses of radio frequency a variety of ways. All units have self-contained displays, and
(RF) energy emitted by a chain of transmitters hundreds of some elaborate units feature built-in moving map displays.
miles apart. Some installations can also drive an external moving map
display, a conventional VOR indicator, or a horizontal
Within any given chain of transmitters, there is a master situation indicator (HSI). Course deviation information is
station, and from three to five secondary stations. LORAN- presented as a linear deviation from course—there is no
C units must be able to receive at least a master and two increase in tracking sensitivity as the aircraft approaches
secondary stations to provide navigational information. the waypoint or destination. Pilots must carefully observe
Unlike VOR/DME-based RNAV, where the pilot must select placards, selector switch positions, and annunciator
the appropriate VOR/DME or VORTAC frequency, there is indications when utilizing LORAN-C because aircraft
not a frequency selection in LORAN-C. The most advanced installations can vary widely. The pilot’s familiarity with
units automatically select the optimum chain for navigation. unit operation through AFM/POH supplements and operating
Other units rely upon the pilot to select the appropriate chain guides cannot be overemphasized.
with a manual entry.
LORAN-C Notices to Airmen (NOTAMs) should be
After the LORAN-C receiver has been turned on, the unit reviewed prior to relying on LORAN-C for navigation.
must be initialized before it can be used for navigation. While LORAN-C NOTAMs are issued to announce outages for
this can be accomplished in flight, it is preferable to perform specific chains and transmitters. Pilots may obtain LORAN-C
this task, which can take several minutes, on the ground. NOTAMs from FSS briefers only upon request.
The methods for initialization are as varied as the number
of different models of receivers. Some require pilot input

15-31

The prudent pilot never relies solely on one means of satellites and a barometric altimeter (baro-aiding) to detect an
navigation when others are available for backup and cross- integrity anomaly. For receivers capable of doing so, RAIM
check. Pilots should never become so dependent upon the needs six satellites in view (or five satellites with baro-aiding)
extensive capabilities of LORAN-C that other methods of to isolate the corrupt satellite signal and remove it from the
navigation are neglected. navigation solution. Baro-aiding is a method of augmenting
the GPS integrity solution by using a nonsatellite input
Global Positioning System source. GPS derived altitude should not be relied upon to
The GPS is a satellite-based radio navigation system. Its determine aircraft altitude since the vertical error can be quite
RNAV guidance is worldwide in scope. There are no symbols large and no integrity is provided. To ensure that baro-aiding
for GPS on aeronautical charts as it is a space-based system is available, the current altimeter setting must be entered into
with global coverage. Development of the system is underway the receiver as described in the operating manual.
so that GPS is capable of providing the primary means of
electronic navigation. Portable and yoke mounted units are RAIM messages vary somewhat between receivers; however,
proving to be very popular in addition to those permanently generally there are two types. One type indicates that there
installed in the aircraft. Extensive navigation databases are are not enough satellites available to provide RAIM integrity
common features in aircraft GPS receivers. monitoring and another type indicates that the RAIM integrity
monitor has detected a potential error that exceeds the limit
The GPS is a satellite radio navigation and time dissemination for the current phase of flight. Without RAIM capability, the
system developed and operated by the U.S. Department of pilot has no assurance of the accuracy of the GPS position.
Defense (DOD). Civilian interface and GPS system status
is available from the U.S. Coast Guard. Selective Availability
Selective Availability (SA) is a method by which the accuracy
It is not necessary to understand the technical aspects of of GPS is intentionally degraded. This feature is designed
GPS operation to use it in VFR/instrument flight rules (IFR) to deny hostile use of precise GPS positioning data. SA was
navigation. It does differ significantly from conventional, discontinued on May 1, 2000, but many GPS receivers are
ground-based electronic navigation, and awareness of those designed to assume that SA is still active.
differences is important. Awareness of equipment approvals
and limitations is critical to the safety of flight. The GPS constellation of 24 satellites is designed so that a
minimum of five satellites are always observable by a user
The GPS navigation system broadcasts a signal that is used anywhere on earth. The receiver uses data from a minimum of
by receivers to determine precise position anywhere in the four satellites above the mask angle (the lowest angle above
world. The receiver tracks multiple satellites and determines the horizon at which a receiver can use a satellite).
a pseudorange measurement to determine the user location.
A minimum of four satellites is necessary to establish an VFR Use of GPS
accurate three-dimensional position. The Department of GPS navigation has become a great asset to VFR pilots,
Defense (DOD) is responsible for operating the GPS satellite providing increased navigation capability and enhanced
constellation and monitors the GPS satellites to ensure proper situational awareness, while reducing operating costs due
operation. to greater ease in flying direct routes. While GPS has many
benefits to the VFR pilot, care must be exercised to ensure
The status of a GPS satellite is broadcast as part of the data that system capabilities are not exceeded.
message transmitted by the satellite. GPS status information
is also available by means of the U.S. Coast Guard navigation Types of receivers used for GPS navigation under VFR are
information service at (703) 313-5907 or online at http:// varied, from a full IFR installation being used to support a
www.navcen.uscg.gov/. Additionally, satellite status is VFR flight, to a VFR only installation (in either a VFR or IFR
available through the Notice to Airmen (NOTAM) system. capable aircraft) to a hand-held receiver. The limitations of
each type of receiver installation or use must be understood
The GPS receiver verifies the integrity (usability) of the by the pilot to avoid misusing navigation information. In all
signals received from the GPS constellation through receiver cases, VFR pilots should never rely solely on one system
autonomous integrity monitoring (RAIM) to determine if of navigation. GPS navigation must be integrated with
a satellite is providing corrupted information. At least one other forms of electronic navigation as well as pilotage
satellite, in addition to those required for navigation, must be and dead reckoning. Only through the integration of these
in view for the receiver to perform the RAIM function; thus, techniques can the VFR pilot ensure accuracy in navigation.
RAIM needs a minimum of five satellites in view, or four

15-32

Some critical concerns in VFR use of GPS include RAIM in certain situations of aircraft-satellite geometry, causing a
capability, database currency and antenna location. loss of navigation signal. These losses, coupled with a lack
of RAIM capability, could present erroneous position and
RAIM Capability navigation information with no warning to the pilot.
Many VFR GPS receivers and all hand-held units have no
RAIM alerting capability. Loss of the required number of While the use of a hand-held GPS for VFR operations is not
satellites in view, or the detection of a position error, cannot limited by regulation, modification of the aircraft, such as
be displayed to the pilot by such receivers. In receivers installing a panel- or yoke-mounted holder, is governed by 14
with no RAIM capability, no alert would be provided to the CFR part 43. Pilots should consult with a mechanic to ensure
pilot that the navigation solution had deteriorated, and an compliance with the regulation and a safe installation.
undetected navigation error could occur. A systematic cross-
check with other navigation techniques would identify this Tips for Using GPS for VFR Operations
failure, and prevent a serious deviation. Always check to see if the unit has RAIM capability. If no
RAIM capability exists, be suspicious of a GPS displayed
In many receivers, an up-datable database is used for position when any disagreement exists with the position
navigation fixes, airports, and instrument procedures. derived from other radio navigation systems, pilotage, or
These databases must be maintained to the current update dead reckoning.
for IFR operation, but no such requirement exists for VFR
use. However, in many cases, the database drives a moving Check the currency of the database, if any. If expired, update
map display which indicates Special Use Airspace and the the database using the current revision. If an update of an
various classes of airspace, in addition to other operational expired database is not possible, disregard any moving map
information. Without a current database the moving map display of airspace for critical navigation decisions. Be aware
display may be outdated and offer erroneous information to that named waypoints may no longer exist or may have
VFR pilots wishing to fly around critical airspace areas, such been relocated since the database expired. At a minimum,
as a Restricted Area or a Class B airspace segment. Numerous the waypoints planned to be used should be checked against
pilots have ventured into airspace they were trying to avoid a current official source, such as the A/FD, or a Sectional
by using an outdated database. If there is not a current data Aeronautical Chart.
base in the receiver, disregard the moving map display when
making critical navigation decisions. While a hand-held GPS receiver can provide excellent
navigation capability to VFR pilots, be prepared for
In addition, waypoints are added, removed, relocated, or re- intermittent loss of navigation signal, possibly with no RAIM
named as required to meet operational needs. When using warning to the pilot. If mounting the receiver in the aircraft,
GPS to navigate relative to a named fix, a current database be sure to comply with 14 CFR part 43.
must be used to properly locate a named waypoint. Without
the update, it is the pilot’s responsibility to verify the Plan flights carefully before taking off. If navigating to user-
waypoint location referencing to an official current source, defined waypoints, enter them before flight, not on the fly.
such as the A/FD, sectional chart, or en route chart. Verify the planned flight against a current source, such as a
current sectional chart. There have been cases in which one
In many VFR installations of GPS receivers, antenna location pilot used waypoints created by another pilot that were not
is more a matter of convenience than performance. In IFR where the pilot flying was expecting. This generally resulted
installations, care is exercised to ensure that an adequate in a navigation error. Minimize head-down time in the aircraft
clear view is provided for the antenna to see satellites. If an and keep a sharp lookout for traffic, terrain, and obstacles.
alternate location is used, some portion of the aircraft may Just a few minutes of preparation and planning on the ground
block the view of the antenna, causing a greater opportunity makes a great difference in the air.
to lose navigation signal.
Another way to minimize head-down time is to become very
This is especially true in the case of hand-helds. The use of familiar with the receiver’s operation. Most receivers are not
hand-held receivers for VFR operations is a growing trend, intuitive. The pilot must take the time to learn the various
especially among rental pilots. Typically, suction cups are keystrokes, knob functions, and displays that are used in
used to place the GPS antennas on the inside of aircraft the operation of the receiver. Some manufacturers provide
windows. While this method has great utility, the antenna computer-based tutorials or simulations of their receivers.
location is limited by aircraft structure for optimal reception Take the time to learn about the particular unit before using
of available satellites. Consequently, signal losses may occur it in flight.

15-33

In summary, be careful not to rely on GPS to solve all VFR Pilots should be especially vigilant for other traffic while
navigational problems. Unless an IFR receiver is installed in operating near VFR waypoints. The same effort to see
accordance with IFR requirements, no standard of accuracy and avoid other aircraft near VFR waypoints is necessary,
or integrity has been assured. While the practicality of as is the case when operating near VORs and NDBs. In
GPS is compelling, the fact remains that only the pilot can fact, the increased accuracy of navigation through the use
navigate the aircraft, and GPS is just one of the pilot’s tools of GPS demands even greater vigilance, as off-course
to do the job. deviations among different pilots and receivers is less.
When operating near a VFR waypoint, use whatever ATC
VFR Waypoints services are available, even if outside a class of airspace
VFR waypoints provide VFR pilots with a supplementary where communications are required. Regardless of the class
tool to assist with position awareness while navigating of airspace, monitor the available ATC frequency closely for
visually in aircraft equipped with area navigation receivers. information on other aircraft operating in the vicinity. It is
VFR waypoints should be used as a tool to supplement current also a good idea to turn on landing light(s) when operating
navigation procedures. The uses of VFR waypoints include near a VFR waypoint to make the aircraft more conspicuous
providing navigational aids for pilots unfamiliar with an area, to other pilots, especially when visibility is reduced.
waypoint definition of existing reporting points, enhanced
navigation in and around Class B and Class C airspace, and Lost Procedures
enhanced navigation around Special Use Airspace. VFR
pilots should rely on appropriate and current aeronautical Getting lost in an aircraft is a potentially dangerous situation
charts published specifically for visual navigation. If especially when low on fuel. If a pilot becomes lost, there
operating in a terminal area, pilots should take advantage of are some good common sense procedures to follow. If a
the Terminal Area Chart available for that area, if published. town or city cannot be seen, the first thing to do is climb,
The use of VFR waypoints does not relieve the pilot of any being mindful of traffic and weather conditions. An increase
responsibility to comply with the operational requirements in altitude increases radio and navigation reception range,
of 14 CFR part 91. and also increases radar coverage. If flying near a town or
city, it might be possible to read the name of the town on a
VFR waypoint names (for computer entry and flight plans) water tower.
consist of five letters beginning with the letters “VP”
and are retrievable from navigation databases. The VFR If the aircraft has a navigational radio, such as a VOR or ADF
waypoint names are not intended to be pronounceable, receiver, it can be possible to determine position by plotting
and they are not for use in ATC communications. On VFR an azimuth from two or more navigational facilities. If GPS
charts, a stand-alone VFR waypoint is portrayed using the is installed, or a pilot has a portable aviation GPS on board,
same four-point star symbol used for IFR waypoints. VFR it can be used to determine the position and the location of
waypoint collocated with a visual checkpoint on the chart is the nearest airport.
identified by a small magenta flag symbol. A VFR waypoint
collocated with a visual checkpoint is pronounceable based Communicate with any available facility using frequencies
on the name of the visual checkpoint and may be used for shown on the sectional chart. If contact is made with a
ATC communications. Each VFR waypoint name appears in controller, radar vectors may be offered. Other facilities may
parentheses adjacent to the geographic location on the chart. offer direction finding (DF) assistance. To use this procedure,
Latitude/longitude data for all established VFR waypoints the controller requests the pilot to hold down the transmit
may be found in the appropriate regional A/FD. button for a few seconds and then release it. The controller
may ask the pilot to change directions a few times and repeat
When filing VFR flight plans, use the five-letter identifier as the transmit procedure. This gives the controller enough
a waypoint in the route of flight section if there is an intended information to plot the aircraft position and then give vectors
course change at that point or if used to describe the planned to a suitable landing site. If the situation becomes threatening,
route of flight. This VFR filing would be similar to VOR use transmit the situation on the emergency frequency 121.5 MHz
in a route of flight. Pilots must use the VFR waypoints only and set the transponder to 7700. Most facilities, and even
when operating under VFR conditions. airliners, monitor the emergency frequency.

Any VFR waypoints intended for use during a flight should Flight Diversion
be loaded into the receiver while on the ground and prior to
departure. Once airborne, pilots should avoid programming There probably comes a time when a pilot is not able to
routes or VFR waypoint chains into their receivers. make it to the planned destination. This can be the result of
unpredicted weather conditions, a system malfunction, or

15-34

poor preflight planning. In any case, the pilot needs to be After selecting the most appropriate alternate, approximate
able to safely and efficiently divert to an alternate destination. the magnetic course to the alternate using a compass rose
Before any cross-country flight, check the charts for airports or airway on the sectional chart. If time permits, try to start
or suitable landing areas along or near the route of flight. the diversion over a prominent ground feature. However,
Also, check for navigational aids that can be used during a in an emergency, divert promptly toward your alternate.
diversion. Attempting to complete all plotting, measuring, and
computations involved before diverting to the alternate may
Computing course, time, speed, and distance information in only aggravate an actual emergency.
flight requires the same computations used during preflight
planning. However, because of the limited flight deck space, Once established on course, note the time, and then use the
and because attention must be divided between flying the winds aloft nearest to your diversion point to calculate a
aircraft, making calculations, and scanning for other aircraft, heading and GS. Once a GS has been calculated, determine
take advantage of all possible shortcuts and rule-of-thumb a new arrival time and fuel consumption. Give priority to
computations. flying the aircraft while dividing attention between navigation
and planning. When determining an altitude to use while
When in flight, it is rarely practical to actually plot a course diverting, consider cloud heights, winds, terrain, and radio
on a sectional chart and mark checkpoints and distances. reception.
Furthermore, because an alternate airport is usually not
very far from your original course, actual plotting is seldom Chapter Summary
necessary.
This chapter has discussed the fundamentals of VFR
A course to an alternate can be measured accurately with a navigation. Beginning with an introduction to the charts that
protractor or plotter, but can also be measured with reasonable can be used for navigation to the more technically advanced
accuracy using a straightedge and the compass rose depicted concept of GPS, there is one aspect of navigation that remains
around VOR stations. This approximation can be made on the the same. The pilot is responsible for proper planning and the
basis of a radial from a nearby VOR or an airway that closely execution of that planning to ensure a safe flight.
parallels the course to your alternate. However, remember
that the magnetic heading associated with a VOR radial
or printed airway is outbound from the station. To find the
course TO the station, it may be necessary to determine the
reciprocal of that heading. It is typically easier to navigate
to an alternate airport that has a VOR or NDB facility on
the field.

15-35

15-36

AChaepterr16omedical
Factors

Introduction

It is important for a pilot to be aware of the mental and
physical standards required for the type of flying done. This
chapter provides information on medical certification and on
a variety of aeromedical factors related to flight activities.

16-1

Obtaining a Medical Certificate Health and Physiological Factors
Affecting Pilot Performance
Most pilots must have a valid medical certificate to exercise
the privileges of their airman certificates. Glider and free A number of health factors and physiological effects can be
balloon pilots are not required to hold a medical certificate. linked to flying. Some are minor, while others are important
Sport pilots may hold either a medical certificate or a valid enough to require special attention to ensure safety of flight.
state driver’s license. In some cases, physiological factors can lead to inflight
emergencies. Some important medical factors that a pilot
Acquisition of a medical certificate requires an examination should be aware of include hypoxia, hyperventilation,
by an aviation medical examiner (AME), a physician middle ear and sinus problems, spatial disorientation, motion
with training in aviation medicine designated by the Civil sickness, carbon monoxide (CO) poisoning, stress and
Aerospace Medical Institute (CAMI). There are three classes fatigue, dehydration, and heatstroke. Other subjects include
of medical certificates. The class of certificate needed the effects of alcohol and drugs, anxiety, and excess nitrogen
depends on the type of flying the pilot plans to do. in the blood after scuba diving.

A third-class medical certificate is required for a private or Hypoxia
recreational pilot certificate. It is valid for 3 years for those Hypoxia means “reduced oxygen” or “not enough oxygen.”
individuals who have not reached the age of 40; otherwise it Although any tissue will die if deprived of oxygen long
is valid for 2 years. A commercial pilot certificate requires at enough, usually the most concern is with getting enough
least a second-class medical certificate, which is valid for 1 oxygen to the brain, since it is particularly vulnerable to
year. First-class medical certificates are required for airline oxygen deprivation. Any reduction in mental function while
transport pilots, and are valid for 6 months. flying can result in life-threatening errors. Hypoxia can be
caused by several factors, including an insufficient supply of
The standards are more rigorous for the higher classes of oxygen, inadequate transportation of oxygen, or the inability
certificates. A pilot with a higher class medical certificate of the body tissues to use oxygen. The forms of hypoxia are
has met the requirements for the lower classes as well. Since based on their causes: hypoxic hypoxia, hypemic hypoxia,
the required medical class applies only when exercising the stagnant hypoxia, and histotoxic hypoxia.
privileges of the pilot certificate for which it is required, a first-
class medical certificate would be valid for 1 year if exercising Hypoxic Hypoxia
the privileges of a commercial certificate, and 2 or 3 years,
as appropriate, for exercising the privileges of a private or Hypoxic hypoxia is a result of insufficient oxygen available
recreational certificate. The same applies for a second-class to the body as a whole. A blocked airway and drowning are
medical certificate. The standards for medical certification obvious examples of how the lungs can be deprived of oxygen,
are contained in Title 14 of the Code of Federal Regulations but the reduction in partial pressure of oxygen at high altitude
(14 CFR) part 67 and the requirements for obtaining medical is an appropriate example for pilots. Although the percentage
certificates can be found in 14 CFR part 61. of oxygen in the atmosphere is constant, its partial pressure
decreases proportionately as atmospheric pressure decreases.
Students who have physical limitations, such as impaired As the airplane ascends during flight, the percentage of
vision, loss of a limb, or hearing impairment may be issued each gas in the atmosphere remains the same, but there are
a medical certificate valid for “student pilot privileges fewer molecules available at the pressure required for them
only” while learning to fly. Pilots with disabilities may to pass between the membranes in the respiratory system.
require special equipment installed in the aircraft, such as This decrease in number of oxygen molecules at sufficient
hand controls for pilots with paraplegia. Some disabilities pressure can lead to hypoxic hypoxia.
necessitate a limitation on the individual’s certificate; for
example, impaired hearing would require the limitation Hypemic Hypoxia
“not valid for flight requiring the use of radio.” When all the
knowledge, experience, and proficiency requirements have Hypemic hypoxia occurs when the blood is not able to take
been met and a student can demonstrate the ability to operate up and transport a sufficient amount of oxygen to the cells
the aircraft with the normal level of safety, a “statement of in the body. Hypemic means “not enough blood.” This type
demonstrated ability” (SODA) can be issued. This waiver, of hypoxia is a result of oxygen deficiency in the blood,
or SODA, is valid as long as the physical impairment does rather than a lack of inhaled oxygen, and can be caused by
not worsen. Contact the local Flight Standards District Office a variety of factors. It may be due to reduced blood volume
(FSDO) for more information on this subject. (due to severe bleeding), or it may result from certain blood
diseases, such as anemia. More often hypemic hypoxia

16-2

occurs because hemoglobin, the actual blood molecule that • Lightheaded or dizzy sensation
transports oxygen, is chemically unable to bind oxygen
molecules. The most common form of hypemic hypoxia is • Tingling in fingers and toes
CO poisoning. This is explained in greater detail on page
16-11. Hypemic hypoxia can also be caused by the loss • Numbness
of blood due to blood donation. Blood can require several
weeks to return to normal following a donation. Although As hypoxia worsens, the field of vision begins to narrow, and
the effects of the blood loss are slight at ground level, there instrument interpretation can become difficult. Even with all
are risks when flying during this time. these symptoms, the effects of hypoxia can cause a pilot to
have a false sense of security and be deceived into believing
Stagnant Hypoxia everything is normal. The treatment for hypoxia includes
flying at lower altitudes and/or using supplemental oxygen.
Stagnant means “not flowing,” and stagnant hypoxia, or
ischemia, results when the oxygen-rich blood in the lungs All pilots are susceptible to the effects of oxygen starvation,
is not moving, for one reason or another, to the tissues that regardless of physical endurance or acclimatization. When
need it. An arm or leg “going to sleep” because the blood flying at high altitudes, it is paramount that oxygen be used
flow has accidentally been shut off is one form of stagnant to avoid the effects of hypoxia. The term “time of useful
hypoxia. This kind of hypoxia can also result from shock, consciousness” describes the maximum time the pilot has
the heart failing to pump blood effectively, or a constricted to make rational, life-saving decisions and carry them out at
artery. During flight, stagnant hypoxia can occur with a given altitude without supplemental oxygen. As altitude
excessive acceleration of gravity (Gs). Cold temperatures increases above 10,000 feet, the symptoms of hypoxia
also can reduce circulation and decrease the blood supplied increase in severity, and the time of useful consciousness
to extremities. rapidly decreases. [Figure 16-1]

Histotoxic Hypoxia Altitude Time of Useful Consciousness
The inability of the cells to effectively use oxygen is defined
as histotoxic hypoxia. “Histo” refers to tissues or cells, and 45,000 feet MSL 9 to 15 seconds
“toxic” means poisonous. In this case, enough oxygen is 40,000 feet MSL 15 to 20 seconds
being transported to the cells that need it, but they are unable 35,000 feet MSL 30 to 60 seconds
to make use of it. This impairment of cellular respiration 30,000 feet MSL 1 to 2 minutes
can be caused by alcohol and other drugs, such as narcotics 28,000 feet MSL 2½ to 3 minutes
and poisons. Research has shown that drinking one ounce 25,000 feet MSL 3 to 5 minutes
of alcohol can equate to about an additional 2,000 feet of 22,000 feet MSL 5 to 10 minutes
physiological altitude. 20,000 feet MSL 30 minutes or more

Symptoms of Hypoxia Figure 16-1. Time of useful consciousness.
High-altitude flying can place a pilot in danger of becoming
hypoxic. Oxygen starvation causes the brain and other vital Since symptoms of hypoxia can be different for each individual,
organs to become impaired. One noteworthy attribute of the ability to recognize hypoxia can be greatly improved by
the onset of hypoxia is that the first symptoms are euphoria experiencing and witnessing the effects of it during an altitude
and a carefree feeling. With increased oxygen starvation, chamber “flight.” The Federal Aviation Administration
the extremities become less responsive and flying becomes (FAA) provides this opportunity through aviation physiology
less coordinated. The symptoms of hypoxia vary with the training, which is conducted at the FAA CAMI and at many
individual, but common symptoms include: military facilities across the United States. For information
about the FAA’s one-day physiological training course with
• Cyanosis (blue fingernails and lips) altitude chamber and vertigo demonstrations, visit the FAA
web site: www.faa.gov/pilots/training/airman_education/
• Headache aerospace_physiology/index.cfm.

• Decreased reaction time Hyperventilation
Hyperventilation is the excessive rate and depth of respiration
• Impaired judgment leading to abnormal loss of carbon dioxide from the blood.
This condition occurs more often among pilots than is
• Euphoria generally recognized. It seldom incapacitates completely, but

• Visual impairment

• Drowsiness

16-3

it causes disturbing symptoms that can alarm the uninformed Middle Ear Eustachian Tube
pilot. In such cases, increased breathing rate and anxiety
further aggravate the problem. Hyperventilation can lead to Eardrum
unconsciousness due to the respiratory system’s overriding
mechanism to regain control of breathing.

Pilots encountering an unexpected stressful situation may Outer Ear Auditory Canal
subconsciously increase their breathing rate. If flying at Opening to Throat
higher altitudes, either with or without oxygen, a pilot may
have a tendency to breathe more rapidly than normal, which Figure 16-2. The Eustachian tube allows air pressure to equalize
often leads to hyperventilation. in the middle ear.

Since many of the symptoms of hyperventilation are similar During a climb, middle ear air pressure may exceed the
to those of hypoxia, it is important to correctly diagnose and pressure of the air in the external ear canal, causing the
treat the proper condition. If using supplemental oxygen, eardrum to bulge outward. Pilots become aware of this
check the equipment and flow rate to ensure the symptoms are pressure change when they experience alternate sensations
not hypoxia related. Common symptoms of hyperventilation of “fullness” and “clearing.” During descent, the reverse
include: happens. While the pressure of the air in the external ear
canal increases, the middle ear cavity, which equalized with
• Visual impairment the lower pressure at altitude, is at lower pressure than the
external ear canal. This results in the higher outside pressure,
• Unconsciousness causing the eardrum to bulge inward.

• Lightheaded or dizzy sensation This condition can be more difficult to relieve due to the
fact that the partial vacuum tends to constrict the walls of
• Tingling sensations the Eustachian tube. To remedy this often painful condition,
which also causes a temporary reduction in hearing
• Hot and cold sensations sensitivity, pinch the nostrils shut, close the mouth and lips,
and blow slowly and gently in the mouth and nose.
• Muscle spasms
This procedure forces air through the Eustachian tube into the
The treatment for hyperventilation involves restoring middle ear. It may not be possible to equalize the pressure in
the proper carbon dioxide level in the body. Breathing the ears if a pilot has a cold, an ear infection, or sore throat.
normally is both the best prevention and the best cure for A flight in this condition can be extremely painful, as well as
hyperventilation. In addition to slowing the breathing rate, damaging to the eardrums. If experiencing minor congestion,
breathing into a paper bag or talking aloud helps to overcome nose drops or nasal sprays may reduce the risk of a painful
hyperventilation. Recovery is usually rapid once the breathing ear blockage. Before using any medication, check with an
rate is returned to normal. AME to ensure that it will not affect the ability to fly.

Middle Ear and Sinus Problems
During climbs and descents, the free gas formerly present in
various body cavities expands due to a difference between
the pressure of the air outside the body and that of the air
inside the body. If the escape of the expanded gas is impeded,
pressure builds up within the cavity and pain is experienced.
Trapped gas expansion accounts for ear pain and sinus pain,
as well as a temporary reduction in the ability to hear.

The middle ear is a small cavity located in the bone of the In a similar way, air pressure in the sinuses equalizes with
skull. It is closed off from the external ear canal by the the pressure in the flight deck through small openings
eardrum. Normally, pressure differences between the middle that connect the sinuses to the nasal passages. An upper
ear and the outside world are equalized by a tube leading from respiratory infection, such as a cold or sinusitis, or a nasal
inside each ear to the back of the throat on each side, called allergic condition can produce enough congestion around an
the Eustachian tube. These tubes are usually closed, but open opening to slow equalization. As the difference in pressure
during chewing, yawning, or swallowing to equalize pressure. between the sinuses and the flight deck increases, congestion
Even a slight difference between external pressure and middle may plug the opening. This “sinus block” occurs most
ear pressure can cause discomfort. [Figure 16-2]

16-4

frequently during descent. Slow descent rates can reduce can sometimes cause these systems to supply conflicting
the associated pain. A sinus block can occur in the frontal information to the brain, which can lead to disorientation.
sinuses, located above each eyebrow, or in the maxillary During flight in visual meteorological conditions (VMC),
sinuses, located in each upper cheek. It will usually produce the eyes are the major orientation source and usually prevail
excruciating pain over the sinus area. A maxillary sinus over false sensations from other sensory systems. When
block can also make the upper teeth ache. Bloody mucus these visual cues are removed, as they are in instrument
may discharge from the nasal passages. meteorological conditions (IMC), false sensations can cause
a pilot to quickly become disoriented.
Sinus block can be avoided by not flying with an upper
respiratory infection or nasal allergic condition. Adequate The vestibular system in the inner ear allows the pilot to
protection is usually not provided by decongestant sprays sense movement and determine orientation in the surrounding
or drops to reduce congestion around the sinus openings. environment. In both the left and right inner ear, three
Oral decongestants have side effects that can impair pilot semicircular canals are positioned at approximate right angles
performance. If a sinus block does not clear shortly after to each other. [Figure 16-3] Each canal is filled with fluid
landing, a physician should be consulted. and has a section full of fine hairs. Acceleration of the inner
ear in any direction causes the tiny hairs to deflect, which
Spatial Disorientation and Illusions in turn stimulates nerve impulses, sending messages to the
Spatial disorientation specifically refers to the lack of brain. The vestibular nerve transmits the impulses from
orientation with regard to the position, attitude, or movement the utricle, saccule, and semicircular canals to the brain to
of the airplane in space. The body uses three integrated interpret motion.
systems working together to ascertain orientation and
movement in space. The somatosensory system sends signals from the skin, joints,
and muscles to the brain that are interpreted in relation to the
• Vestibular system—organs found in the inner ear that Earth’s gravitational pull. These signals determine posture.
sense position by the way we are balanced. Inputs from each movement update the body’s position to the
brain on a constant basis. “Seat of the pants” flying is largely
• Somatosensory system—nerves in the skin, muscles, dependent upon these signals. Used in conjunction with visual
and joints, which, along with hearing, sense position and vestibular clues, these sensations can be fairly reliable.
based on gravity, feeling, and sound. However, the body cannot distinguish between acceleration
forces due to gravity and those resulting from maneuvering
• Visual system—eyes, which sense position based on the aircraft, which can lead to sensory illusions and false
what is seen. impressions of an aircraft’s orientation and movement.

All this information comes together in the brain and, most
of the time, the three streams of information agree, giving
a clear idea of where and how the body is moving. Flying

YAW Ampulla of Semicircular Canal
Semicircular Canals
ROLL Otolith Organ

PITCH

ROLL PITCH

YAW Endolymph Fluid Cupola
The semicircular tubes are arranged Vestibular Nerve Hair Cells
at approximately right angles to each
other in the roll, pitch, and yaw axes. 16-5

Figure 16-3. The semicircular canals lie in three planes and sense motions of roll, pitch, and yaw.

Figure 16-4. Human sensation of angular acceleration.

Under normal flight conditions, when there is a visual For this reason, it is important that pilots develop an instrument
reference to the horizon and ground, the sensory system in the cross-check or scan that involves minimal head movement.
inner ear helps to identify the pitch, roll, and yaw movements Take care when retrieving charts and other objects in the flight
of the aircraft. When visual contact with the horizon is lost, deck—if something is dropped, retrieve it with minimal head
the vestibular system becomes unreliable. Without visual movement and be alert for the coriolis illusion.
references outside the aircraft, there are many situations in
which combinations of normal motions and forces create Graveyard Spiral
convincing illusions that are difficult to overcome.
As in other illusions, a pilot in a prolonged coordinated,
Prevention is usually the best remedy for spatial disorientation. constant-rate turn, will have the illusion of not turning.
Unless a pilot has many hours of training in instrument flight, During the recovery to level flight, the pilot will experience
flight should be avoided in reduced visibility or at night when the sensation of turning in the opposite direction. The
the horizon is not visible. A pilot can reduce susceptibility disoriented pilot may return the aircraft to its original turn.
to disorienting illusions through training and awareness, and Because an aircraft tends to lose altitude in turns unless the
learning to rely totally on flight instruments. pilot compensates for the loss in lift, the pilot may notice
a loss of altitude. The absence of any sensation of turning
Vestibular Illusions creates the illusion of being in a level descent. The pilot may
The Leans pull back on the controls in an attempt to climb or stop the
descent. This action tightens the spiral and increases the loss
A condition called the leans can result when a banked of altitude; this illusion is referred to as a graveyard spiral.
attitude, to the left for example, may be entered too slowly [Figure 16-5] At some point, this could lead to a loss of
to set in motion the fluid in the “roll” semicircular tubes. aircraft control.
[Figure 16-4] An abrupt correction of this attitude sets the
fluid in motion, creating the illusion of a banked attitude to the
right. The disoriented pilot may make the error of rolling the
aircraft into the original left banked attitude, or if level flight
is maintained, will feel compelled to lean in the perceived
vertical plane until this illusion subsides.

Coriolis Illusion Figure 16-5. Graveyard spiral.

The coriolis illusion occurs when a pilot has been in a turn
long enough for the fluid in the ear canal to move at the same
speed as the canal. A movement of the head in a different
plane, such as looking at something in a different part of the
flight deck, may set the fluid moving and create the illusion
of turning or accelerating on an entirely different axis.
This action causes the pilot to think the aircraft is doing a
maneuver that it is not. The disoriented pilot may maneuver
the aircraft into a dangerous attitude in an attempt to correct
the aircraft’s perceived attitude.

16-6

Somatogravic Illusion to spatial disorientation, false horizon and autokinesis, are
concerned with only the visual system.
A rapid acceleration, such as experienced during takeoff,
stimulates the otolith organs in the same way as tilting the False Horizon
head backwards. This action creates the somatogravic illusion A sloping cloud formation, an obscured horizon, an aurora
of being in a nose-up attitude, especially in situations without borealis, a dark scene spread with ground lights and stars,
good visual references. The disoriented pilot may push the and certain geometric patterns of ground lights can provide
aircraft into a nose-low or dive attitude. A rapid deceleration inaccurate visual information, or false horizon, for aligning
by quick reduction of the throttle(s) can have the opposite the aircraft correctly with the actual horizon. The disoriented
effect, with the disoriented pilot pulling the aircraft into a pilot may place the aircraft in a dangerous attitude.
nose-up or stall attitude.

Inversion Illusion Autokinesis
An abrupt change from climb to straight-and-level flight can
stimulate the otolith organs enough to create the illusion of In the dark, a stationary light will appear to move about when
tumbling backwards, or inversion illusion. The disoriented stared at for many seconds. The disoriented pilot could lose
pilot may push the aircraft abruptly into a nose-low attitude, control of the aircraft in attempting to align it with the false
possibly intensifying this illusion. movements of this light, called autokinesis.

Elevator Illusion Postural Considerations
An abrupt upward vertical acceleration, as can occur in The postural system sends signals from the skin, joints, and
an updraft, can stimulate the otolith organs to create the muscles to the brain that are interpreted in relation to the
illusion of being in a climb. This is called elevator illusion. Earth’s gravitational pull. These signals determine posture.
The disoriented pilot may push the aircraft into a nose-low Inputs from each movement update the body’s position to
attitude. An abrupt downward vertical acceleration, usually the brain on a constant basis. “Seat of the pants” flying is
in a downdraft, has the opposite effect, with the disoriented largely dependent upon these signals. Used in conjunction
pilot pulling the aircraft into a nose-up attitude. with visual and vestibular clues, these sensations can be
fairly reliable. However, because of the forces acting upon
Visual Illusions the body in certain flight situations, many false sensations
Visual illusions are especially hazardous because pilots rely can occur due to acceleration forces overpowering gravity.
on their eyes for correct information. Two illusions that lead [Figure 16-6] These situations include uncoordinated turns,
climbing turns, and turbulence.

Level Coordinated turn Pull out

Level skid Forward slip Uncoordinated turn

Skid, slip, and uncoordinated turns feel similar.
Pilots feel they are being forced sideways in their seat.

Figure 16-6. Sensations from centrifugal force.

16-7

Demonstration of Spatial Disorientation Tilting to Right or Left
There are a number of controlled aircraft maneuvers a pilot While in a straight-and-level attitude, with the pilot’s eyes
can perform to experiment with spatial disorientation. While closed, the instructor pilot executes a moderate or slight skid
each maneuver will normally create a specific illusion, any to the left with wings level. This creates the illusion of the
false sensation is an effective demonstration of disorientation. body being tilted to the right.
Thus, even if there is no sensation during any of these
maneuvers, the absence of sensation is still an effective Reversal of Motion
demonstration because it illustrates the inability to detect This illusion can be demonstrated in any of the three planes
bank or roll. There are several objectives in demonstrating of motion. While straight and level, with the pilot’s eyes
these various maneuvers. closed, the instructor pilot smoothly and positively rolls the
aircraft to approximately 45° bank attitude while maintaining
1. They teach pilots to understand the susceptibility of heading and pitch attitude. This creates the illusion of a strong
the human system to spatial disorientation. sense of rotation in the opposite direction. After this illusion
is noted, the pilot should open his or her eyes and observe
2. They demonstrate that judgments of aircraft attitude that the aircraft is in a banked attitude.
based on bodily sensations are frequently false.
Diving or Rolling Beyond the Vertical Plane
3. They help decrease the occurrence and degree of This maneuver may produce extreme disorientation. While
disorientation through a better understanding of the in straight-and-level flight, the pilot should sit normally,
relationship between aircraft motion, head movements, either with eyes closed or gaze lowered to the floor. The
and resulting disorientation. instructor pilot starts a positive, coordinated roll toward a
30° or 40° angle of bank. As this is in progress, the pilot
4. They help instill a greater confidence in relying on tilts his or her head forward, looks to the right or left, then
flight instruments for assessing true aircraft attitude. immediately returns his or her head to an upright position.
The instructor pilot should time the maneuver so the roll is
A pilot should not attempt any of these maneuvers at low stopped as the pilot returns his or her head upright. An intense
altitudes, or in the absence of an instructor pilot or an disorientation is usually produced by this maneuver, and the
appropriate safety pilot. pilot experiences the sensation of falling downward into the
direction of the roll.
Climbing While Accelerating
With the pilot’s eyes closed, the instructor pilot maintains In the descriptions of these maneuvers, the instructor pilot is
approach airspeed in a straight-and-level attitude for several doing the flying, but having the pilot do the flying can also
seconds, then accelerates while maintaining straight-and- be a very effective demonstration. The pilot should close his
level attitude. The usual illusion during this maneuver, or her eyes and tilt the head to one side. The instructor pilot
without visual references, is that the aircraft is climbing. tells the pilot what control inputs to perform. The pilot then
attempts to establish the correct attitude or control input with
Climbing While Turning eyes closed and head tilted. While it is clear the pilot has no
With the pilot’s eyes still closed and the aircraft in a straight- idea of the actual attitude, he or she will react to what the
and-level attitude, the instructor pilot now executes, with a senses are saying. After a short time, the pilot will become
relatively slow entry, a well coordinated turn of about 1.5 disoriented and the instructor pilot then tells the pilot to look
positive G (approximately 50° bank) for 90°. While in the up and recover. The benefit of this exercise is that the pilot
turn, without outside visual references and under the effect of experiences the disorientation while flying the aircraft.
the slight positive G, the usual illusion produced is that of a
climb. Upon sensing the climb, the pilot should immediately Coping with Spatial Disorientation
open the eyes to see that a slowly established, coordinated To prevent illusions and their potentially disastrous
turn produces the same sensation as a climb. consequences, pilots can:

Diving While Turning 1. Understand the causes of these illusions and remain
Repeating the previous procedure, except the pilot’s eyes constantly alert for them. Take the opportunity to
should be kept closed until recovery from the turn is experience spatial disorientation illusions in a device
approximately one-half completed, can create the illusion such as a Barany chair, a Vertigon, or a Virtual Reality
of diving while turning. Spatial Disorientation Demonstrator.

16-8

2. Always obtain and understand preflight weather will fly a lower approach, with the risk of striking objects
briefings. along the approach path or landing short. A wider-than-
usual runway can have the opposite effect, with the risk of
3. Before flying in marginal visibility (less than 3 miles) the pilot leveling out the aircraft high and landing hard, or
or where a visible horizon is not evident, such as flight overshooting the runway.
over open water during the night, obtain training and
maintain proficiency in airplane control by reference Runway and Terrain Slopes Illusion
to instruments. An upsloping runway, upsloping terrain, or both, can create
an illusion that the aircraft is at a higher altitude than it
4. Do not continue flight into adverse weather conditions actually is. [Figure 16-7] The pilot who does not recognize
or into dusk or darkness unless proficient in the use of this illusion will fly a lower approach. Downsloping runways
flight instruments. If intending to fly at night, maintain and downsloping approach terrain can have the opposite
night-flight currency and proficiency. Include cross- effect.
country and local operations at various airfields.
Featureless Terrain Illusion
5. Ensure that when outside visual references are used, An absence of surrounding ground features, as in an
they are reliable, fixed points on the Earth’s surface. overwater approach, over darkened areas, or terrain made
featureless by snow, can create an illusion the aircraft is at
6. Avoid sudden head movement, particularly during a higher altitude than it actually is. This illusion, sometimes
takeoffs, turns, and approaches to landing. referred to as the “black hole approach,” causes pilots to fly
a lower approach than is desired.
7. Be physically tuned for flight into reduced visibility.
That is, ensure proper rest, adequate diet, and, if flying Water Refraction
at night, allow for night adaptation Remember that Rain on the windscreen can create an illusion of being at a
illness, medication, alcohol, fatigue, sleep loss, and higher altitude due to the horizon appearing lower than it is.
mild hypoxia are likely to increase susceptibility to This can result in the pilot flying a lower approach.
spatial disorientation.
Haze
8. Most importantly, become proficient in the use of Atmospheric haze can create an illusion of being at a greater
flight instruments and rely upon them. Trust the distance and height from the runway. As a result, the pilot
instruments and disregard your sensory perceptions. will have a tendency to be low on the approach. Conversely,
extremely clear air (clear bright conditions of a high attitude
The sensations that lead to illusions during instrument airport) can give the pilot the illusion of being closer than he
flight conditions are normal perceptions experienced by or she actually is, resulting in a high approach, which may
pilots. These undesirable sensations cannot be completely result in an overshoot or go around. The diffusion of light
prevented, but through training and awareness, pilots can due to water particles on the windshield can adversely affect
ignore or suppress them by developing absolute reliance depth perception. The lights and terrain features normally
on the flight instruments. As pilots gain proficiency in used to gauge height during landing become less effective
instrument flying, they become less susceptible to these for the pilot.
illusions and their effects.
Fog
Optical Illusions Flying into fog can create an illusion of pitching up. Pilots
Of the senses, vision is the most important for safe flight. who do not recognize this illusion will often steepen the
However, various terrain features and atmospheric conditions approach quite abruptly.
can create optical illusions. These illusions are primarily
associated with landing. Since pilots must transition from Ground Lighting Illusions
reliance on instruments to visual cues outside the flight deck for Lights along a straight path, such as a road or lights on moving
landing at the end of an instrument approach, it is imperative trains, can be mistaken for runway and approach lights. Bright
they be aware of the potential problems associated with these runway and approach lighting systems, especially where
illusions, and take appropriate corrective action. The major few lights illuminate the surrounding terrain, may create the
illusions leading to landing errors are described below. illusion of less distance to the runway. The pilot who does not
recognize this illusion will often fly a higher approach.
Runway Width Illusion
A narrower-than-usual runway can create an illusion the
aircraft is at a higher altitude than it actually is, especially
when runway length-to-width relationships are comparable.
[Figure 16-7] The pilot who does not recognize this illusion

16-9

Narrower runway Wider runway Runway width illusion

Normal Approach Normal Approach • A narrower-than-usual runway can
create an illusion that the aircraft
25 is higher than it actually is, leading
25 to a lower approach.

25 25 • A wider-than-usual runway can
create an illusion that the aircraft is
lower than it actually is, leading to
a higher approach.

Narrower runway Wider runway

25 25

Downsloping runway Upsloping runway Runway slope illusion

Normal Approach Normal Approach • A downsloping runway can create
the illusion that the aircraft is lower
than it actually is, leading to a
higher approach.

• An upsloping runway can create
the illusion that the aircraft is higher
than it actually is, leading to a lower
approach.

Downsloping runway Upsloping runway

Normal approach
Approach due to illusion

Figure 16-7. Runway illusions.
16-10

How To Prevent Landing Errors Due to Optical It is important to remember that experiencing airsickness is
Illusions no reflection on one’s ability as a pilot. If prone to motion
To prevent these illusions and their potentially hazardous sickness, let the flight instructor know, there are techniques
consequences, pilots can: that can be used to overcome this problem. For example,
avoid lessons in turbulent conditions until becoming more
1. Anticipate the possibility of visual illusions during comfortable in the aircraft, or start with shorter flights and
approaches to unfamiliar airports, particularly at night graduate to longer instruction periods. If symptoms of motion
or in adverse weather conditions. Consult airport sickness are experienced during a lesson, opening fresh air
diagrams and the Airport/Facility Directory (A/FD) for vents, focusing on objects outside the airplane, and avoiding
information on runway slope, terrain, and lighting. unnecessary head movements may help alleviate some of
the discomfort. Although medications like Dramamine can
2. Make frequent reference to the altimeter, especially prevent airsickness in passengers, they are not recommended
during all approaches, day and night. while flying since they can cause drowsiness and other
problems.
3. If possible, conduct aerial visual inspection of
unfamiliar airports before landing. Carbon Monoxide (CO) Poisoning
CO is a colorless and odorless gas produced by all internal
4. Use Visual Approach Slope Indicator (VASI) or combustion engines. Attaching itself to the hemoglobin in
Precision Approach Path Indicator (PAPI) systems the blood about 200 times more easily than oxygen, CO
for a visual reference, or an electronic glideslope, prevents the hemoglobin from carrying oxygen to the cells,
whenever they are available. resulting in hypemic hypoxia. The body requires up to 48
hours to dispose of CO. If severe enough, the CO poisoning
5. Utilize the visual descent point (VDP) found on many can result in death. Aircraft heater vents and defrost vents
nonprecision instrument approach procedure charts. may provide CO a passageway into the cabin, particularly
if the engine exhaust system has a leak or is damaged. If a
6. Recognize that the chances of being involved in an strong odor of exhaust gases is detected, assume that CO is
approach accident increase when some emergency or present. However, CO may be present in dangerous amounts
other activity distracts from usual procedures. even if no exhaust odor is detected. Disposable, inexpensive
CO detectors are widely available. In the presence of CO,
7. Maintain optimum proficiency in landing procedures. these detectors change color to alert the pilot of the presence
of CO. Some effects of CO poisoning are headache, blurred
In addition to the sensory illusions due to misleading inputs vision, dizziness, drowsiness, and/or loss of muscle power.
to the vestibular system, a pilot may also encounter various Any time a pilot smells exhaust odor, or any time that these
visual illusions during flight. Illusions rank among the symptoms are experienced, immediate corrective actions
most common factors cited as contributing to fatal aviation should be taken. These include turning off the heater, opening
accidents. fresh air vents and windows, and using supplemental oxygen,
if available.
Sloping cloud formations, an obscured horizon, a dark scene
spread with ground lights and stars, and certain geometric Tobacco smoke also causes CO poisoning. Smoking at
patterns of ground light can create illusions of not being sea level can raise the CO concentration in the blood and
aligned correctly with the actual horizon. Various surface result in physiological effects similar to flying at 8,000 feet.
features and atmospheric conditions encountered in landing Besides hypoxia, tobacco causes diseases and physiological
can create illusions of being on the wrong approach path. debilitation that are medically disqualifying for pilots.
Landing errors due to these illusions can be prevented by
anticipating them during approaches, inspecting unfamiliar Stress
airports before landing, using electronic glideslope or VASI Stress is the body’s response to physical and psychological
systems when available, and maintaining proficiency in demands placed upon it. The body’s reaction to stress includes
landing procedures. releasing chemical hormones (such as adrenaline) into the
blood, and increasing metabolism to provide more energy
Motion Sickness to the muscles. Blood sugar, heart rate, respiration, blood
Motion sickness, or airsickness, is caused by the brain pressure, and perspiration all increase. The term “stressor”
receiving conflicting messages about the state of the body. A is used to describe an element that causes an individual to
pilot may experience motion sickness during initial flights, but
it generally goes away within the first few lessons. Anxiety
and stress, which may be experienced at the beginning of
flight training, can contribute to motion sickness. Symptoms
of motion sickness include general discomfort, nausea,
dizziness, paleness, sweating, and vomiting.

16-11

experience stress. Examples of stressors include physical Acute fatigue has many causes, but the following are among
stress (noise or vibration), physiological stress (fatigue), and the most important for the pilot:
psychological stress (difficult work or personal situations).
• Mild hypoxia (oxygen deficiency)
Stress falls into two broad categories, acute (short term) and
chronic (long term). Acute stress involves an immediate • Physical stress
threat that is perceived as danger. This is the type of stress that
triggers a “fight or flight” response in an individual, whether • Psychological stress and
the threat is real or imagined. Normally, a healthy person can
cope with acute stress and prevent stress overload. However, • Depletion of physical energy resulting from
ongoing acute stress can develop into chronic stress. psychological stress

Chronic stress can be defined as a level of stress that presents • Sustained psychological stress
an intolerable burden, exceeds the ability of an individual
to cope, and causes individual performance to fall sharply. Sustained psychological stress accelerates the glandular
Unrelenting psychological pressures, such as loneliness, secretions that prepare the body for quick reactions during
financial worries, and relationship or work problems can an emergency. These secretions make the circulatory and
produce a cumulative level of stress that exceeds a person’s respiratory systems work harder, and the liver releases energy
ability to cope with the situation. When stress reaches these to provide the extra fuel needed for brain and muscle work.
levels, performance falls off rapidly. Pilots experiencing When this reserve energy supply is depleted, the body lapses
this level of stress are not safe and should not exercise their into generalized and severe fatigue.
airman privileges. Pilots who suspect they are suffering from
chronic stress should consult a physician. Acute fatigue can be prevented by proper diet and adequate
rest and sleep. A well-balanced diet prevents the body from
needing to consume its own tissues as an energy source.
Adequate rest maintains the body’s store of vital energy.

Fatigue Chronic fatigue, extending over a long period of time, usually
Fatigue is frequently associated with pilot error. Some of has psychological roots, although an underlying disease is
the effects of fatigue include degradation of attention and sometimes responsible. Continuous high stress levels produce
concentration, impaired coordination, and decreased ability chronic fatigue. Chronic fatigue is not relieved by proper diet
to communicate. These factors seriously influence the and adequate rest and sleep, and usually requires treatment
ability to make effective decisions. Physical fatigue results by a physician. An individual may experience this condition
from sleep loss, exercise, or physical work. Factors such as in the form of weakness, tiredness, palpitations of the heart,
stress and prolonged performance of cognitive work result breathlessness, headaches, or irritability. Sometimes chronic
in mental fatigue. fatigue even creates stomach or intestinal problems and
generalized aches and pains throughout the body. When the
Like stress, fatigue falls into two broad categories: acute condition becomes serious enough, it leads to emotional
and chronic. Acute fatigue is short term and is a normal illness.
occurrence in everyday living. It is the kind of tiredness
people feel after a period of strenuous effort, excitement, or If suffering from acute fatigue, stay on the ground. If fatigue
lack of sleep. Rest after exertion and 8 hours of sound sleep occurs in the flight deck, no amount of training or experience
ordinarily cures this condition. can overcome the detrimental effects. Getting adequate rest
is the only way to prevent fatigue from occurring. Avoid
A special type of acute fatigue is skill fatigue. This type of flying without a full night’s rest, after working excessive
fatigue has two main effects on performance: hours, or after an especially exhausting or stressful day. Pilots
who suspect they are suffering from chronic fatigue should
• Timing disruption—Appearing to perform a task as consult a physician.
usual, but the timing of each component is slightly off.
This makes the pattern of the operation less smooth, Dehydration and Heatstroke
because the pilot performs each component as though it Dehydration is the term given to a critical loss of water from
were separate, instead of part of an integrated activity. the body. Causes of dehydration are hot flight decks and
flight lines, wind, humidity, and diuretic drinks—coffee, tea,
• Disruption of the perceptual field—Concentrating alcohol, and caffeinated soft drinks. Some common signs of
attention upon movements or objects in the center of dehydration are headache, fatigue, cramps, sleepiness, and
vision and neglecting those in the periphery. This is dizziness.
accompanied by loss of accuracy and smoothness in
control movements.

16-12

The first noticeable effect of dehydration is fatigue, which Alcohol
in turn makes top physical and mental performance difficult, Alcohol impairs the efficiency of the human body.
if not impossible. Flying for long periods in hot summer [Figure 16-8] Studies have proved that drinking and
temperatures or at high altitudes increases the susceptibility performance deterioration are closely linked. Pilots must
to dehydration because these conditions tend to increase the make hundreds of decisions, some of them time-critical,
rate of water loss from the body. during the course of a flight. The safe outcome of any flight
depends on the ability to make the correct decisions and take
To help prevent dehydration, drink two to four quarts of the appropriate actions during routine occurrences, as well
water every 24 hours. Since each person is physiologically as abnormal situations. The influence of alcohol drastically
different, this is only a guide. Most people are aware of the reduces the chances of completing a flight without incident.
eight-glasses-a-day guide: If each glass of water is eight Even in small amounts, alcohol can impair judgment,
ounces, this equates to 64 ounces, which is two quarts. If decrease sense of responsibility, affect coordination, constrict
this fluid is not replaced, fatigue progresses to dizziness, visual field, diminish memory, reduce reasoning power, and
weakness, nausea, tingling of hands and feet, abdominal lower attention span. As little as one ounce of alcohol can
cramps, and extreme thirst. decrease the speed and strength of muscular reflexes, lessen

The key for pilots is to be continually aware of their condition. Type Beverage Typical Serving Pure Alcohol
Most people become thirsty with a 1.5 quart deficit, or a loss (oz) Content (oz)
of 2 percent of total body weight. This level of dehydration Table Wine
triggers the “thirst mechanism.” The problem is that the thirst Light Beer 4.0 .48
mechanism arrives too late and is turned off too easily. A Aperitif Liquor 12.0 .48
small amount of fluid in the mouth will turn this mechanism Champagne .38
off and the replacement of needed body fluid is delayed. Vodka 1.5 .48
Whiskey 4.0 .50
Other steps to prevent dehydration include: 1.0 .50
0.01–0.05 1.25
• Carrying a container in order to measure daily water (10–50 mg%)
intake. average individual appears normal

• Staying ahead—not relying on the thirst sensation as 0.03–0.12* mild euphoria, talkativeness, decreased
an alarm. If plain water is offensive, add some sport (30–120 mg%) inhibitions, decreased attention, impaired
drink flavoring to make it more acceptable. judgment, increased reaction time

• Limiting daily intake of caffeine and alcohol (both 0.09–0.25 emotional instability, loss of critical
are diuretics and stimulate increased production of (90–250 mg%) judgment, impairment of memory and
urine). comprehension, decreased sensory
response, mild muscular incoordination
Heatstroke is a condition caused by any inability of the body
to control its temperature. Onset of this condition may be 0.18–0.30 confusion, dizziness, exaggerated
recognized by the symptoms of dehydration, but also has been (180–300 mg%) emotions (anger, fear, grief) impaired
known to be recognized only by complete collapse. visual perception, decreased pain
sensation, impaired balance, staggering
To prevent these symptoms, it is recommended that an ample gait, slurred speech, moderate muscular
supply of water be carried and used at frequent intervals on incoordination
any long flight, whether thirsty or not. The body normally
absorbs water at the rate of 1.2 to 1.5 quarts per hour. 0.27–0.40 apathy, impaired consciousness, stupor,
Individuals should drink one quart per hour for severe heat (270–400 mg%) significantly decreased response to
stress conditions or one pint per hour for moderate stress stimulation, severe muscular
conditions. If the aircraft has a canopy or roof window, incoordination, inability to stand or walk,
wearing light-colored, porous clothing and a hat will help vomiting, incontinence of urine and feces
provide protection from the sun. Keeping the flight deck well
ventilated aids in dissipating excess heat. 0.35–0.50 unconsciousness, depressed or
(350–500 mg%) abolished reflexes, abnormal body
temperature, coma; possible death from
respiratory paralysis (450 mg% or above)

* Legal limit for motor vehicle operation in most states is 0.08
or 0.10% (80–100 mg of alcohol per dL of blood).

Figure 16-8. Impairement scale with alcohol use.

16-13

the efficiency of eye movements while reading, and increase pain relievers, and cough suppressants have primary
the frequency at which errors are committed. Impairments effects that may impair judgment, memory, alertness,
in vision and hearing occur at alcohol blood levels due to as coordination, vision, and the ability to make calculations.
little as one drink. [Figure 16-9] Others, such as antihistamines, blood pressure
drugs, muscle relaxants, and agents to control diarrhea and
The alcohol consumed in beer and mixed drinks is ethyl motion sickness have side effects that may impair the same
alcohol, a central nervous system depressant. From a medical critical functions. Any medication that depresses the nervous
point of view, it acts on the body much like a general system, such as a sedative, tranquilizer, or antihistamine, can
anesthetic. The “dose” is generally much lower and more make a pilot more susceptible to hypoxia.
slowly consumed in the case of alcohol, but the basic effects
on the human body are similar. Alcohol is easily and quickly Painkillers are grouped into two broad categories: analgesics
absorbed by the digestive tract. The bloodstream absorbs and anesthetics. Analgesics are drugs that reduce pain,
about 80 to 90 percent of the alcohol in a drink within 30 while anesthetics are drugs that deaden pain or cause loss
minutes when ingested on an empty stomach. The body of consciousness.
requires about 3 hours to rid itself of all the alcohol contained
in one mixed drink or one beer. Over-the-counter analgesics, such as acetylsalicylic acid
(aspirin), acetaminophen (Tylenol), and ibuprofen (Advil)
While experiencing a hangover, a pilot is still under the have few side effects when taken in the correct dosage.
influence of alcohol. Although a pilot may think he or she is Although some people are allergic to certain analgesics or
functioning normally, motor and mental response impairment may suffer from stomach irritation, flying usually is not
is still present. Considerable amounts of alcohol can remain restricted when taking these drugs. However, flying is almost
in the body for over 16 hours, so pilots should be cautious always precluded while using prescription analgesics, such
about flying too soon after drinking. as drugs containing propoxyphene (e.g., Darvon), oxycodone
(e.g., Percodan), meperidine (e.g., Demerol), and codeine
Altitude multiplies the effects of alcohol on the brain. When since these drugs are known to cause side effects such as
combined with altitude, the alcohol from two drinks may have mental confusion, dizziness, headaches, nausea, and vision
the same effect as three or four drinks. Alcohol interferes problems.
with the brain’s ability to utilize oxygen, producing a form
of histotoxic hypoxia. The effects are rapid because alcohol Anesthetic drugs are commonly used for dental and surgical
passes quickly into the bloodstream. In addition, the brain procedures. Most local anesthetics used for minor dental and
is a highly vascular organ that is immediately sensitive to outpatient procedures wear off within a relatively short period
changes in the blood’s composition. For a pilot, the lower of time. The anesthetic itself may not limit flying as much
oxygen availability at altitude and the lower capability of as the actual procedure and subsequent pain.
the brain to use what oxygen is there, add up to a deadly
combination. Stimulants are drugs that excite the central nervous
system and produce an increase in alertness and activity.
Intoxication is determined by the amount of alcohol in the Amphetamines, caffeine, and nicotine are all forms of
bloodstream. This is usually measured as a percentage by stimulants. Common uses of these drugs include appetite
weight in the blood. 14 CFR part 91 requires that blood suppression, fatigue reduction, and mood elevation. Some
alcohol level be less than .04 percent and that 8 hours pass of these drugs may cause a stimulant reaction, even though
between drinking alcohol and piloting an airplane. A pilot this reaction is not their primary function. In some cases,
with a blood alcohol level of .04 percent or greater after stimulants can produce anxiety and mood swings, both of
8 hours cannot fly until the blood alcohol falls below that which are dangerous when flying.
amount. Even though blood alcohol may be well below .04
percent, a pilot cannot fly sooner than 8 hours after drinking Depressants are drugs that reduce the body’s functioning in
alcohol. Although the regulations are quite specific, it is a many areas. These drugs lower blood pressure, reduce mental
good idea to be more conservative than the regulations. processing, and slow motor and reaction responses. There are
several types of drugs that can cause a depressing effect on the
Drugs body, including tranquilizers, motion sickness medication,
Pilot performance can be seriously degraded by both some types of stomach medication, decongestants, and
prescription and over-the-counter medications, as well antihistamines. The most common depressant is alcohol.
as by the medical conditions for which they are taken.
Many medications, such as tranquilizers, sedatives, strong

16-14

Some drugs that are classified as neither stimulants nor The dangers of illegal drugs also are well documented.
depressants have adverse effects on flying. For example, Certain illegal drugs can have hallucinatory effects that occur
some antibiotics can produce dangerous side effects, such as days or weeks after the drug is taken. Obviously, these drugs
balance disorders, hearing loss, nausea, and vomiting. While have no place in the aviation community.
many antibiotics are safe for use while flying, the infection
requiring the antibiotic may prohibit flying. In addition, 14 CFR prohibits pilots from performing crewmember
unless specifically prescribed by a physician, do not take duties while using any medication that affects the body in
more than one drug at a time, and never mix drugs with any way contrary to safety. The safest rule is not to fly as a
alcohol, because the effects are often unpredictable. crewmember while taking any medication, unless approved to
do so by the FAA. If there is any doubt regarding the effects
of any medication, consult an AME before flying.

Psychoactive Range of Effects Development Prolonged Use of Withdrawal Symptoms
Drugs After Prolonged Use
From To of Tolerance Large Amounts
Beer Convulsions, shakes,
Wine Relaxation, lowered Loss of body control, Moderate Liver damage, ulcers, hallucinations, loss of memory,
Hard Liquor inhibitions, reduced passing out (also chronic diarrhea, uncontrolled muscular spasms,
Alcohol intensity of physical causing physical amnesia, vomiting, psychosis
sensations, digestive injuries), susceptibility brain damage, internal
upsets, body heat loss, to pneumonia, bleeding, debilitation
reduced muscular cessation of breathing
coordination.

Sedative Hypnotics Barbiturates: Relaxation, lowered Passing out, loss of Moderate Amnesia, confusion,
- Nembutal inhibitions, reduced body control, stupor, drowsiness, personality
- Phenobarbital intensity of physical severe depression of changes
- Seconal sensations, digestive respiration, possible
upsets, body heat loss, death (Effects are
Tranquilizers: reduced muscular exaggerated when
- Valium coordination used in combination
- Librium with alcohol—
- Quaaludes synergistic effect.)

Opiates Opium Suppression of pain, Clammy skin, High Depressed sexual drive, Watery eyes, runny nose,
Morphine lowered blood pressure convulsions, High lethargy, general severe back pains, stomach
Heroin and respiratory rate, coma, respiratory physical debilitation, cramps, sleeplessness,
Codeine constipation, disruption depression, possible infections, hepatitis nausea, diarrhea, sweating,
Dilaudid of menstrual cycle, death muscle spasms
Percodan hallucinations, sleep
Darvon
Methadone

Dexedrine Increased blood Paranoid reaction, Psychosis, insomnia, Severe depression, both
temporary psychosis, paranoia, nervous physical and mental (not true
Methamphetamine pressure and pulse irritability, convulsions, system damage (not for caffeine)
palpitations (not generally true for
Diet Pills rate, appetite loss, generally true for caffeine)
caffeine)
Stimulants Ritalin increased alertness,

Cocaine dilated and dried out

Caffeine bronchi, restlessness,

insomnia

Psychedelics LSD Distorted perceptions, Psychosis, High Psychosis, continued Occasional flashback
Mescaline hallucinations, hallucinations, Moderate hallucinations, mental phenomena, depression
Psilocybin confusion, vomiting vomiting, anxiety, disruption
PCP panic, stupor.
With PCP: Aggressive
Marijuana behavior, catatonia,
Hashish convulsions, coma,
high blood pressure

THC Sedation, euphoria, Distorted perception, Amotivation (loss of No true withdrawal symptoms
drive) except possible depression
increased appetite, anxiety, panic

altered mental processes

Figure 16-9. Adverse affects of various drugs.

16-15

Altitude-Induced Decompression Sickness (DCS) • If one of the symptoms is joint pain, keep the affected
Decompression sickness (DCS) describes a condition area still; do not try to work pain out by moving the
characterized by a variety of symptoms resulting from joint around.
exposure to low barometric pressures that cause inert gases
(mainly nitrogen), normally dissolved in body fluids and • Upon landing seek medical assistance from an FAA
tissues, to come out of physical solution and form bubbles. medical officer, AME, military flight surgeon, or
Nitrogen is an inert gas normally stored throughout the a hyperbaric medicine specialist. Be aware that a
human body (tissues and fluids) in physical solution. When physician not specialized in aviation or hypobaric
the body is exposed to decreased barometric pressures (as in medicine may not be familiar with this type of medical
flying an unpressurized aircraft to altitude, or during a rapid problem.
decompression), the nitrogen dissolved in the body comes out
of solution. If the nitrogen is forced to leave the solution too • Definitive medical treatment may involve the use of
rapidly, bubbles form in different areas of the body, causing a a hyperbaric chamber operated by specially trained
variety of signs and symptoms. The most common symptom is personnel.
joint pain, which is known as “the bends.” [Figure 16-10]
• Delayed signs and symptoms of altitude-induced DCS
What to do when altitude-induced DCS occurs: can occur after return to ground level regardless of
presence during flight.
• Put on oxygen mask immediately and switch the
regulator to 100 percent oxygen. DCS After Scuba Diving
Scuba diving subjects the body to increased pressure, which
• Begin an emergency descent and land as soon as allows more nitrogen to dissolve in body tissues and fluids.
possible. Even if the symptoms disappear during [Figure 16-11] The reduction of atmospheric pressure that
descent, land and seek medical evaluation while accompanies flying can produce physical problems for scuba
continuing to breathe oxygen. divers. A pilot or passenger who intends to fly after scuba

DCS Type Bubble Location Signs & Symptoms (Clinical Manifestations)
BENDS Mostly large joints
of the body (elbows, • Localized deep pain, ranging from mild (a “niggle”) to excruciating–sometimes a dull
NEUROLOGIC shoulders, hip, wrists, ache, but rarely a sharp pain
Manifestations knees, ankles)
Brain • Active and passive motion of the joint aggravating the pain
CHOKES • Pain occurring at altitude, during the descent, or many hours later
SKIN BENDS Spinal Cord
• Confusion or memory loss
Peripheral Nerves • Headache
• Spots in visual field (scotoma), tunnel vision, double vision (diplopia), or blurry vision
Lungs • Unexplained extreme fatigue or behavior changes
• Seizures, dizziness, vertigo, nausea, vomiting, and unconsciousness
Skin
• Abnormal sensations such as burning, stinging, and tingling around the lower chest
and back

• Symptoms spreading from the feet up and possibly accompanied by ascending
weakness or paralysis

• Girdling abdominal or chest pain

• Urinary and rectal incontinence
• Abnormal sensations, such as numbness, burning, stinging and tingling (paresthesia)
• Muscle weakness or twitching

• Burning deep chest pain (under the sternum)
• Pain aggravated by breathing
• Shortness of breath (dyspnea)
• Dry constant cough

• Itching usually around the ears, face, neck, arms, and upper torso
• Sensation of tiny insects crawling over the skin
• Mottled or marbled skin usually around the shoulders, upper chest, and abdomen,

accompanied by itching
• Swelling of the skin, accompanied by tiny scar-like skin depressions (pitting edema)

Figure 16-10. Signs and symptoms of altitude decompression sickness.

16-16

feet should be at least 24 hours after any scuba dive. These
recommended altitudes are actual flight altitudes above mean
sea level (AMSL) and not pressurized cabin altitudes. This
takes into consideration the risk of decompression of the
aircraft during flight.

Vision in Flight

Of all the senses, vision is the most important for safe flight.
Most of the things perceived while flying are visual or heavily
supplemented by vision. As remarkable and vital as it is,
vision is subject to limitations, such as illusions and blind
spots. The more a pilot understands about the eyes and how
they function, the easier it is to use vision effectively and
compensate for potential problems.

Figure 16-11. To avoid the bends, scuba divers must not fly for The eye functions much like a camera. Its structure includes
specific time periods following dives. an aperture, a lens, a mechanism for focusing, and a surface
for registering images. Light enters through the cornea at the
diving should allow the body sufficient time to rid itself of front of the eyeball, travels through the lens, and falls on the
excess nitrogen absorbed during diving. If not, DCS due to retina. The retina contains light sensitive cells that convert
evolved gas can occur during exposure to low altitude and light energy into electrical impulses that travel through nerves
create a serious inflight emergency. to the brain. The brain interprets the electrical signals to form
images. There are two kinds of light-sensitive cells in the
The recommended waiting time before going to flight eyes: rods and cones. [Figure 16-12]
altitudes of up to 8,000 feet is at least 12 hours after diving
that does not require controlled ascent (nondecompression The cones are responsible for all color vision, from
stop diving), and at least 24 hours after diving that does appreciating a glorious sunset to discerning the subtle shades
require controlled ascent (decompression stop diving). The in a fine painting. Cones are present throughout the retina, but
waiting time before going to flight altitudes above 8,000

The rods and Rods and
cones (film) of Cones
the retina are
the receptors Fovea
which record (All Cones)
the image and
transmit it
through the
optic nerve to
the brain for
interpretation.

Rod Concentration Lens
Iris

Optic Nerve PUPIL CORNEA
Retina The pupil (aperture) is the opening at Light passes through the cornea (the
the center of the iris. The size of the transparent window on the front of the
Figure 16-12. The human eye. pupil is adjusted to control the amount eye) and then through the lens to
of light entering the eye. focus on the retina.

16-17

are concentrated toward the center of the field of vision at the and focusing on distant light sources, no matter how dim,
back of the retina. There is a small pit called the fovea where helps prevent the onset of empty-field myopia.
almost all the light sensing cells are cones. This is the area
where most “looking” occurs (the center of the visual field Night Vision
where detail, color sensitivity, and resolution are highest). It is estimated that once fully adapted to darkness, the rods are
10,000 times more sensitive to light than the cones, making
While the cones and their associated nerves are well suited them the primary receptors for night vision. Since the cones
to detecting fine detail and color in high light levels, the are concentrated near the fovea, the rods are also responsible
rods are better able to detect movement and provide vision for much of the peripheral vision. The concentration of cones
in dim light. The rods are unable to discern color but are in the fovea can make a night blind spot in the center of the
very sensitive at low light levels. The trouble with rods is field of vision. To see an object clearly at night, the pilot must
that a large amount of light overwhelms them, and they take expose the rods to the image. This can be done by looking 5°
a long time to “reset” and adapt to the dark again. There are to 10° off center of the object to be seen. This can be tried in
so many cones in the fovea that the very center of the visual a dim light in a darkened room. When looking directly at the
field hardly has virtually no rods at all. So in low light, the light, it dims or disappears altogether. When looking slightly
middle of the visual field is not very sensitive, but farther off center, it becomes clearer and brighter.
from the fovea, the rods are more numerous and provide the
major portion of night vision. Refer to Figure 16-14. When looking directly at an object,
the image is focused mainly on the fovea, where detail is
The area where the optic nerve enters the eyeball has no rods best seen. At night, the ability to see an object in the center
or cones, leaving a blind spot in the field of vision. Normally, of the visual field is reduced as the cones lose much of their
each eye compensates for the other’s blind spot. Figure 16-13 sensitivity and the rods become more sensitive. Looking off
provides a dramatic example of the eye’s blind spot. Cover center can help compensate for this night blind spot. Along
the right eye and hold this page at arm’s length. Focus the left with the loss of sharpness (acuity) and color at night, depth
eye on the X on the right side of the windshield and notice perception and judgment of size may be lost.
what happens to the airplane while slowly bringing the page
closer to the eye. While the cones adapt rapidly to changes in light intensities,
the rods take much longer. Walking from bright sunlight into
Empty-Field Myopia a dark movie theater is an example of this dark adaptation
Empty-field myopia is a condition that usually occurs when period experience. The rods can take approximately 30
flying above the clouds or in a haze layer that provides minutes to fully adapt to darkness. A bright light, however,
nothing specific to focus on outside the aircraft. This causes can completely destroy night adaptation, leaving night
the eyes to relax and seek a comfortable focal distance which vision severely compromised while the adaptation process
may range from 10 to 30 feet. For the pilot, this means is repeated.
looking without seeing, which is dangerous. Searching out

Figure 16-13. The eye’s blind spot.
16-18

Cones active Red flight deck lighting also helps preserve night vision, but
red light severely distorts some colors and completely washes
out the color red. This makes reading an aeronautical chart
difficult. A dim white light or a carefully directed flashlight
can enhance night reading ability. While flying at night, keep
the instrument panel and interior lights turned up no higher
than necessary. This helps to see outside references more
easily. If the eyes become blurry, blinking more frequently
often helps.

Diet and general physical health have an impact on how well
a pilot can see in the dark. Deficiencies in vitamins A and C
have been shown to reduce night acuity. Other factors, such
as CO poisoning, smoking, alcohol, certain drugs, and a lack
of oxygen also can greatly decrease night vision.

Night blind spot Night Vision Illusions
There are many different types of visual illusions that
Rods active commonly occur at night. Anticipating and staying aware
of them is usually the best way to avoid them.
Figure 16-14. Night blind spot.
Autokinesis
Hypoxia also affects vision. Sharp clear vision, (with the Autokinesis is caused by staring at a single point of light
best being equal to 20-20 vision) requires significant oxygen against a dark background for more than a few seconds.
especially at night. As altitude increases, the available oxygen After a few moments, the light appears to move on its own.
decreases, degrading night vision. Compounding the problem To prevent this illusion, focus the eyes on objects at varying
is fatigue, which minimizes physiological well being. Adding distances and avoid fixating on one target. Be sure to maintain
fatigue to high altitude exposure is a recipe for disaster. a normal scan pattern.
In fact, if flying at night at an altitude of 12,000 feet, the
pilot may actually see elements of his or her normal vision False Horizon
missing or not in focus. Missing visual elements resemble A false horizon can occur when the natural horizon is obscured
the missing pixels in a digital image while unfocused vision or not readily apparent. It can be generated by confusing
is dim and washed out. bright stars and city lights. It can also occur while flying
toward the shore of an ocean or a large lake. Because of the
For the pilot suffering the effects of hypoxic hypoxia, a simple relative darkness of the water, the lights along the shoreline
descent to a lower altitude may not be sufficient to reestablish can be mistaken for stars in the sky. [Figure 16-15]
vision. For example, a climb from 8,000 feet to 12,000 feet for
30 minutes does not mean a descent to 8,000 feet will rectify Night Landing Illusions
the problem. Visual acuity may not be regained for over an Landing illusions occur in many forms. Above featureless
hour. Thus, it is important to remember, altitude and fatigue terrain at night, there is a natural tendency to fly a lower-
have a profound effect on a pilot’s ability to see. than-normal approach. Elements that cause any type of
visual obscurities, such as rain, haze, or a dark runway
Several things can be done to keep the eyes adapted to environment can also cause low approaches. Bright lights,
darkness. The first is obvious: avoid bright lights before and steep surrounding terrain, and a wide runway can produce the
during flight. For 30 minutes before a night flight, avoid any illusion of being too low, with a tendency to fly a higher-than-
bright light sources, such as headlights, landing lights, strobe normal approach. A set of regularly spaced lights along a road
lights, or flashlights. If a bright light is encountered, close or highway can appear to be runway lights. Pilots have even
one eye to keep it light sensitive. This allows the use of that mistaken the lights on moving trains as runway or approach
eye to see again when the light is gone. lights. Bright runway or approach lighting systems can create
the illusion that the airplane is closer to the runway, especially
where few lights illuminate the surrounding terrain.

16-19

Actual horizon Apparent horizon

Figure 16-15. At night, the horizon may be hard to discern due to dark terrain and misleading light patterns on the ground.

Pilots who are flying at night should strongly consider oxygen
supplementation at altitudes and times not required by the
FAA, especially at night, when critical judgement and hand-
eye coordination is necessary (e.g., IFR), or if a smoker or
not perfectly healthy.

Chapter Summary

This chapter provides an introduction to aeromedical factors
relating to flight activities. More detailed information on
the subjects discussed in this chapter is available in the
Aeronautical Information Manual (AIM) and online at www.
faa.gov/pilots/safety/pilotsafetybrochures.

16-20

AChaepterr17onautical
Decision-Making

Introduction

Aeronautical decision-making (ADM) is decision-making
in a unique environment—aviation. It is a systematic
approach to the mental process used by pilots to consistently
determine the best course of action in response to a given set
of circumstances. It is what a pilot intends to do based on the
latest information he or she has.

17-1

The importance of learning and understanding effective History of ADM
ADM skills cannot be overemphasized. While progress is
continually being made in the advancement of pilot training For over 25 years, the importance of good pilot judgment, or
methods, aircraft equipment and systems, and services aeronautical decision-making (ADM), has been recognized
for pilots, accidents still occur. Despite all the changes in as critical to the safe operation of aircraft, as well as accident
technology to improve flight safety, one factor remains the avoidance. The airline industry, motivated by the need to
same: the human factor which leads to errors. It is estimated reduce accidents caused by human factors, developed the first
that approximately 80 percent of all aviation accidents are training programs based on improving ADM. Crew resource
related to human factors and the vast majority of these management (CRM) training for flight crews is focused on
accidents occur during landing (24.1 percent) and takeoff the effective use of all available resources: human resources,
(23.4 percent). [Figure 17-1] hardware, and information supporting ADM to facilitate crew
cooperation and improve decision-making. The goal of all
ADM is a systematic approach to risk assessment and stress flight crews is good ADM and the use of CRM is one way
management. To understand ADM is to also understand how to make good decisions.
personal attitudes can influence decision-making and how
those attitudes can be modified to enhance safety in the flight Research in this area prompted the Federal Aviation
deck. It is important to understand the factors that cause Administration (FAA) to produce training directed at
humans to make decisions and how the decision-making improving the decision-making of pilots and led to current
process not only works, but can be improved. FAA regulations that require that decision-making be taught
as part of the pilot training curriculum. ADM research,
This chapter focuses on helping the pilot improve his or development, and testing culminated in 1987 with the
her ADM skills with the goal of mitigating the risk factors publication of six manuals oriented to the decision-making
associated with flight. Advisory Circular (AC) 60-22, needs of variously rated pilots. These manuals provided
Aeronautical Decision-Making, provides background multifaceted materials designed to reduce the number
references, definitions, and other pertinent information about of decision related accidents. The effectiveness of these
ADM training in the general aviation (GA) environment. materials was validated in independent studies where student
[Figure 17-2] pilots received such training in conjunction with the standard
flying curriculum. When tested, the pilots who had received
ADM training made fewer inflight errors than those who had

Percentage of general aviation accidents

Flight Time Flight Time Flight Time
2% 83% 15%

23.4% 24.1%

15.7%

13%

9.7%

3.5% 3.3% 4.7%

2.6%

Preflights/ Takeoff/ Climb Cruise Descent Maneuvering Approach Landing Other
Taxi Initial Climb

FigFuirgeur1e7-116.-1T.hTehpeerficgeunrteagaeboovfeaivlilautsitornataesccthideepnetsrcaesntthaegye roeflaavteiattoiotnheacdciifdfeernetnstapshtahseeysroeflafltiegthot.thNeodteifftehraetntthpehgarseeasteosftflpiegrhcte. ntage of
accNidoetenttshatatkteheplgarceeatdeusrtipnegracemntiangoer poef raccecnidtaegnetsotfatkheeptolatacel fdliugrhint.g a minor percentage of the total flight; takeoff or landing phases.

17-2

FFiigguurree1176--22..ATdhveisAordyvCisiorrcyulCarir(cAuCla)r6, 0A-C226,0A-2er2oAnaeurotincaaluDticeaclisDioencMisiaokninMg,ackainrrgiecsaarrwieesalathwoefailnthforomf iantifoonrmfoartitohne tphilaotttthoelepailront.
nshoot ureldcebievefadmAiDliaMr training. The differences were statistically 3. Learning how to recognize and cope with stress.

significant and ranged from about 10 to 50 percent fewer 4. Developing risk assessment skills.
judgment errors. In the operational environment, an operator 5. Using all resources.
flying about 400,000 hours annually demonstrated a 54

percent reduction in accident rate after using these materials 6. Evaluating the effectiveness of one’s ADM skills.
for recurrency training.

Contrary to popular opinion, good judgment can be taught. Risk management is an important component of ADM.
Tradition held that good judgment was a natural by-product When a pilot follows good decision-making practices, the
of experience, but as pilots continued to log accident-free inherent risk in a flight is reduced or even eliminated. The
ability to make good decisions is based upon direct or indirect

flight hours, a corresponding increase of good judgment experience and education.
was assumed. Building upon the foundation of conventional

decision-making, ADM enhances the process to decrease Consider automotive seat belt use. In just two decades, seat
the probability of human error and increase the probability belt use has become the norm, placing those who do not

of a safe flight. ADM provides a structured, systematic wear seat belts outside the norm, but this group may learn
approach to analyzing changes that occur during a flight to wear a seat belt by either direct or indirect experience. For
and how these changes might affect a flight’s safe outcome. example, a driver learns through direct experience about the
The ADM process addresses all aspects of decision-making value of wearing a seat belt when he or she is involved in a car

in the flight deck and identifies the steps involved in good accident that leads to a personal injury. An indirect learning

decision-making. experience occurs when a loved one is injured during a car

accident because he or she failed to wear a seat belt.

Steps for good decision-making are:

1. Identifying personal attitudes hazardous to safe While poor decision-making in everyday life does not always
flight. lead to tragedy, the margin for error in aviation is thin. Since
ADM enhances management of an aeronautical environment,
2. Learning behavior modification techniques. all pilots should become familiar with and employ ADM.

17-3

Crew Resource Management (CRM) and prop’s operation and he has been told that damage to a prop
Single-Pilot Resource Management could cause a catastrophic failure. This assessment leads him
to cancel his flight.
While CRM focuses on pilots operating in crew environments,
many of the concepts apply to single-pilot operations. Many Therefore, elements or factors affecting individuals are
CRM principles have been successfully applied to single-pilot different and profoundly impact decision-making. These
aircraft, and led to the development of Single-Pilot Resource are called human factors and can transcend education,
Management (SRM). SRM is defined as the art and science experience, health, physiological aspects, etc.
of managing all the resources (both on-board the aircraft
and from outside sources) available to a single pilot (prior Another example of risk assessment was the flight of a
and during flight) to ensure that the successful outcome Beechcraft King Air equipped with deicing and anti-icing.
of the flight. SRM includes the concepts of ADM, Risk The pilot deliberately flew into moderate to severe icing
Management (RM), Task Management (TM), Automation conditions while ducking under cloud cover. A prudent pilot
Management (AM), Controlled Flight Into Terrain (CFIT) would assess the risk as high and beyond the capabilities of
Awareness, and Situational Awareness (SA). SRM training the aircraft, yet this pilot did the opposite. Why did the pilot
helps the pilot maintain situational awareness by managing take this action?
the automation and associated aircraft control and navigation
tasks. This enables the pilot to accurately assess and manage Past experience prompted the action. The pilot had
risk and make accurate and timely decisions. successfully flown into these conditions repeatedly although
the icing conditions were previously forecast 2,000 feet
SRM is all about helping pilots learn how to gather above the surface. This time, the conditions were forecast
information, analyze it, and make decisions. Although the from the surface. Since the pilot was in a hurry and failed
flight is coordinated by a single person and not an onboard to factor in the difference between the forecast altitudes,
flight crew, the use of available resources such as air traffic he assigned a low risk to the hazard and took a chance. He
control (ATC) and flight service station (FSS) replicates the and the passengers died from a poor risk assessment of the
principles of CRM. situation.

Hazard and Risk Hazardous Attitudes and Antidotes
Being fit to fly depends on more than just a pilot’s physical
Two defining elements of ADM are hazard and risk. Hazard condition and recent experience. For example, attitude will
is a real or perceived condition, event, or circumstance that a affect the quality of decisions. Attitude is a motivational
pilot encounters. When faced with a hazard, the pilot makes predisposition to respond to people, situations, or events in a
an assessment of that hazard based upon various factors. The given manner. Studies have identified five hazardous attitudes
pilot assigns a value to the potential impact of the hazard, that can interfere with the ability to make sound decisions
which qualifies the pilot’s assessment of the hazard—risk. and exercise authority properly: anti-authority, impulsivity,
invulnerability, macho, and resignation. [Figure 17-3]
Therefore, risk is an assessment of the single or cumulative
hazard facing a pilot; however, different pilots see hazards Hazardous attitudes contribute to poor pilot judgment but
differently. For example, the pilot arrives to preflight and can be effectively counteracted by redirecting the hazardous
discovers a small, blunt type nick in the leading edge at the attitude so that correct action can be taken. Recognition of
middle of the aircraft’s prop. Since the aircraft is parked hazardous thoughts is the first step toward neutralizing them.
on the tarmac, the nick was probably caused by another After recognizing a thought as hazardous, the pilot should
aircraft’s prop wash blowing some type of debris into the label it as hazardous, then state the corresponding antidote.
propeller. The nick is the hazard (a present condition). The Antidotes should be memorized for each of the hazardous
risk is prop fracture if the engine is operated with damage attitudes so they automatically come to mind when needed.
to a prop blade.

The seasoned pilot may see the nick as a low risk. He Risk
realizes this type of nick diffuses stress over a large area, is During each flight, the single pilot makes many decisions
located in the strongest portion of the propeller, and based on under hazardous conditions. To fly safely, the pilot needs to
experience, he doesn’t expect it to propagate a crack which assess the degree of risk and determine the best course of
can lead to high risk problems. He does not cancel his flight. action to mitigate risk.
The inexperienced pilot may see the nick as a high risk factor
because he is unsure of the affect the nick will have on the

17-4

The Five Hazardous Attitudes

Anti-Authority: “Don’t tell me.”
This attitude is found in people who do not like anyone telling them what to do. In a sense, they are saying, “No one can tell me
what to do.” They may be resentful of having someone tell them what to do, or may regard rules, regulations, and procedures as
silly or unnecessary. However, it is always your prerogative to question authority if you feel it is in error.

Impulsivity: “Do it quickly.”
This is the attitude of people who frequently feel the need to do something, anything, immediately. They do not stop to think about
what they are about to do; they do not select the best alternative, and they do the first thing that comes to mind.

Invulnerability: “It won’t happen to me.”
Many people falsely believe that accidents happen to others, but never to them. They know accidents can happen, and they know
that anyone can be affected. However, they never really feel or believe that they will be personally involved. Pilots who think this way
are more likely to take chances and increase risk.

Macho: “I can do it.”
Pilots who are always trying to prove that they are better than anyone else think, “I can do it—I'll show them.” Pilots with this
type of attitude will try to prove themselves by taking risks in order to impress others. While this pattern is thought to be a male
characteristic, women are equally susceptible.

Resignation: “What’s the use?”
Pilots who think, “What’s the use?” do not see themselves as being able to make a great deal of difference in what happens to them.
When things go well, the pilot is apt to think that it is good luck. When things go badly, the pilot may feel that someone is out to get
me, or attribute it to bad luck. The pilot will leave the action to others, for better or worse. Sometimes, such pilots will even go along
with unreasonable requests just to be a "nice guy."

Figure 17-3. The five hazardous attitudes identified through past and contemporary study.

Assessing Risk Several risk assessment models are available to assist in the
process of assessing risk. The models, all taking slightly
For the single pilot, assessing risk is not as simple as it sounds. different approaches, seek a common goal of assessing risk
For example, the pilot acts as his or her own quality control in an objective manner. Two are illustrated below.
in making decisions. If a fatigued pilot who has flown 16
hours is asked if he or she is too tired to continue flying, the The most basic tool is the risk matrix. [Figure 17-4] It
answer may be no. Most pilots are goal oriented and when assesses two items: the likelihood of an event occurring and
asked to accept a flight, there is a tendency to deny personal the consequence of that event.
limitations while adding weight to issues not germane to the
mission. For example, pilots of helicopter emergency services Risk Assessment Matrix
(EMS) have been known (more than other groups) to make
flight decisions that add significant weight to the patient’s Severity
welfare. These pilots add weight to intangible factors (the
patient in this case) and fail to appropriately quantify actual Likelihood Catastrophic Critical Marginal Negligible
hazards such as fatigue or weather when making flight
decisions. The single pilot who has no other crew member Probable High High Serious
for consultation must wrestle with the intangible factors that Occasional
draw one into a hazardous position. Therefore, he or she has High Serious
a greater vulnerability than a full crew. Remote
Improbable Serious Medium Low

Examining National Transportation Safety Board (NTSB) Figure 17-4. This risk matrix can be used for almost any operation
reports and other accident research can help a pilot learn to by assigning likelihood and consequence. In the case presented,
assess risk more effectively. For example, the accident rate the pilot assigned a likelihood of occassional and the severity as
during night VFR decreases by nearly 50 percent once a catastrophic. As one can see, this falls in the high risk area.
pilot obtains 100 hours, and continues to decrease until the
1,000 hour level. The data suggest that for the first 500 hours,
pilots flying VFR at night might want to establish higher
personal limitations than are required by the regulations
and, if applicable, apply instrument flying skills in this
environment.

17-5

Likelihood of an Event Mitigating Risk
Likelihood is nothing more than taking a situation and Risk assessment is only part of the equation. After determining
determining the probability of its occurrence. It is rated as the level of risk, the pilot needs to mitigate the risk. For
probable, occasional, remote, or improbable. For example, a example, the pilot flying from point A to point B (50 miles)
pilot is flying from point A to point B (50 miles) in marginal in MVFR conditions has several ways to reduce risk:
visual flight rules (MVFR) conditions. The likelihood of
encountering potential instrument meteorological conditions • Wait for the weather to improve to good visual flight
(IMC) is the first question the pilot needs to answer. The rules (VFR) conditions.
experiences of other pilots coupled with the forecast, might
cause the pilot to assign “occasional” to determine the • Take a pilot who is certified as an IFR pilot.
probability of encountering IMC.
• Delay the flight.
The following are guidelines for making assignments.
• Cancel the flight.
• Probable—an event will occur several times.
• Drive.
• Occasional—an event will probably occur
sometime. One of the best ways to single pilots can mitigate risk is to
use the IMSAFE checklist to determine physical and mental
• Remote—an event is unlikely to occur, but is readiness for flying:
possible.
1. Illness—Am I sick? Illness is an obvious pilot risk.
• Improbable—an event is highly unlikely to occur.
2. Medication—Am I taking any medicines that might
Severity of an Event affect my judgment or make me drowsy?
The next element is the severity or consequence of a
pilot’s action(s). It can relate to injury and/or damage. If 3. Stress—Am I under psychological pressure from the
the individual in the example above is not an instrument job? Do I have money, health, or family problems?
flight rules (IFR) pilot, what are the consequences of him Stress causes concentration and performance
or her encountering inadvertent IMC conditions? In this problems. While the regulations list medical conditions
case, because the pilot is not IFR rated, the consequences that require grounding, stress is not among them.
are catastrophic. The following are guidelines for this The pilot should consider the effects of stress on
assignment. performance.

• Catastrophic—results in fatalities, total loss 4. Alcohol—Have I been drinking within 8 hours?
Within 24 hours? As little as one ounce of liquor, one
• Critical—severe injury, major damage bottle of beer, or four ounces of wine can impair flying
skills. Alcohol also renders a pilot more susceptible
• Marginal—minor injury, minor damage to disorientation and hypoxia.

• Negligible—less than minor injury, less than minor 5. Fatigue—Am I tired and not adequately rested?
system damage Fatigue continues to be one of the most insidious
hazards to flight safety, as it may not be apparent to
Simply connecting the two factors as shown in Figure 17-4 a pilot until serious errors are made.
indicates the risk is high and the pilot must either not fly, or
fly only after finding ways to mitigate, eliminate, or control 6. Eating—Have I eaten enough of the proper foods to
the risk. keep adequately nourished during the entire flight?

Although the matrix in Figure 17-4 provides a general The PAVE Checklist
viewpoint of a generic situation, a more comprehensive Another way to mitigate risk is to perceive hazards. By
program can be made that is tailored to a pilot’s flying. incorporating the PAVE checklist into preflight planning,
[Figure 17-5] This program includes a wide array of aviation the pilot divides the risks of flight into four categories: Pilot-
related activities specific to the pilot and assesses health, in-command (PIC), Aircraft, enVironment, and External
fatigue, weather, capabilities, etc. The scores are added and pressures (PAVE) which form part of a pilot’s decision-
the overall score falls into various ranges, with the range making process.
representative of actions that a pilot imposes upon himself
or herself.

17-6

Pilot’s Name RISK ASSESSMENT To
Flight From

SLEEP 2 HOW IS THE DAY GOING? 3
1. Did not sleep well or less than 8 hours 0 1. Seems like one thing after another (late, 0
2. Slept well
4 making errors, out of step) 1
HOW DO YOU FEEL? 0 2. Great day 3
1. Have a cold or ill 2
2. Feel great IS THE FLIGHT
3. Feel a bit off 1. Day?
2. Night?

WEATHER AT TERMINATION 1 PLANNING 3
1. Greater than 5 miles visibility and 3,000 feet 1. Rush to get off ground
3 2. No hurry 1
ceilings 4 3. Used charts and computer to assist
2. At least 3 miles visibility and 1,000 feet ceilings, 4. Used computer program for all planning 0
Yes 3
but less than 3,000 feet ceilings and 5 miles 5. Did you verify weight and balance? No 0
visibility Yes 0
3. IMC conditions 6. Did you evaluate performance? No 3
Yes 0
Column total 7. Do you brief your passangers on the No 3
ground and in flight? Yes 0
No 2

Column total

TOTAL SCORE

Low Risk
Endangerment

0 Not Complex Flight 10 Exercise Caution 20 Area of Concern 30

Figure 17-5. Example of a more comprehensive risk assessment program.

17-7

With the PAVE checklist, pilots have a simple way to • Does this aircraft have sufficient fuel capacity, with
remember each category to examine for risk prior to each reserves, for trip legs planned?
flight. Once a pilot identifies the risks of a flight, he or she
needs to decide whether the risk or combination of risks can • Does the fuel quantity delivered match the fuel
be managed safely and successfully. If not, make the decision quantity ordered?
to cancel the flight. If the pilot decides to continue with the
flight, he or she should develop strategies to mitigate the V = EnVironment
risks. One way a pilot can control the risks is to set personal Weather
minimums for items in each risk category. These are limits Weather is an major environmental consideration. Earlier
unique to that individual pilot’s current level of experience it was suggested pilots set their own personal minimums,
and proficiency. especially when it comes to weather. As pilots evaluate
the weather for a particular flight, they should consider the
For example, the aircraft may have a maximum crosswind following:
component of 15 knots listed in the aircraft flight manual
(AFM), and the pilot has experience with 10 knots of direct • What are the current ceiling and visibility? In
crosswind. It could be unsafe to exceed a 10 knots crosswind mountainous terrain, consider having higher minimums
component without additional training. Therefore, the 10 kts for ceiling and visibility, particularly if the terrain is
crosswind experience level is that pilot’s personal limitation unfamiliar.
until additional training with a certificated flight instructor
(CFI) provides the pilot with additional experience for flying • Consider the possibility that the weather may be
in crosswinds that exceed 10 knots. different than forecast. Have alternative plans and
be ready and willing to divert, should an unexpected
One of the most important concepts that safe pilots change occur.
understand is the difference between what is “legal” in terms
of the regulations, and what is “smart” or “safe” in terms of • Consider the winds at the airports being used and the
pilot experience and proficiency. strength of the crosswind component.

P = Pilot in Command (PIC) • If flying in mountainous terrain, consider whether there
The pilot is one of the risk factors in a flight. The pilot are strong winds aloft. Strong winds in mountainous
must ask, “Am I ready for this trip?” in terms of experience, terrain can cause severe turbulence and downdrafts
recency, currency, physical and emotional condition. The and be very hazardous for aircraft even when there is
IMSAFE checklist provides the answers. no other significant weather.

A = Aircraft • Are there any thunderstorms present or forecast?
What limitations will the aircraft impose upon the trip? Ask
the following questions: • If there are clouds, is there any icing, current or
forecast? What is the temperature/dew point spread
• Is this the right aircraft for the flight? and the current temperature at altitude? Can descent
be made safely all along the route?
• Am I familiar with and current in this aircraft? Aircraft
performance figures and the AFM are based on a brand • If icing conditions are encountered, is the pilot
new aircraft flown by a professional test pilot. Keep experienced at operating the aircraft’s deicing or
that in mind while assessing personal and aircraft anti-icing equipment? Is this equipment in good
performance. condition and functional? For what icing conditions
is the aircraft rated, if any?
• Is this aircraft equipped for the flight? Instruments?
Lights? Navigation and communication equipment Terrain
adequate? Evaluation of terrain is another important component of
analyzing the flight environment.
• Can this aircraft use the runways available for the trip
with an adequate margin of safety under the conditions • To avoid terrain and obstacles, especially at night or
to be flown? in low visibility, determine safe altitudes in advance
by using the altitudes shown on VFR and IFR charts
• Can this aircraft carry the planned load? during preflight planning.

• Can this aircraft operate at the altitudes needed for the • Use maximum elevation figures (MEFs) and other
trip? easily obtainable data to minimize chances of an
inflight collision with terrain or obstacles.

17-8

Airport • The desire to impress someone. (Probably the two
most dangerous words in aviation are “Watch this!”)
• What lights are available at the destination and
alternate airports? VASI/PAPI or ILS glideslope • The desire to satisfy a specific personal goal (“get-
guidance? Is the terminal airport equipped with them? home-itis,” “get-there-itis,” and “let’s-go-itis”).
Are they working? Will the pilot need to use the radio
to activate the airport lights? • The pilot’s general goal-completion orientation.

• Check the Notices to Airmen (NOTAMS) for closed • Emotional pressure associated with acknowledging
runways or airports. Look for runway or beacon lights that skill and experience levels may be lower than a
out, nearby towers, etc. pilot would like them to be. Pride can be a powerful
external factor!
• Choose the flight route wisely. An engine failure gives
the nearby airports supreme importance. Managing External Pressures
Management of external pressure is the single most important
• Are there shorter or obstructed fields at the destination key to risk management because it is the one risk factor
amd/or alternate airports? category that can cause a pilot to ignore all the other risk
factors. External pressures put time-related pressure on the
Airspace pilot and figure into a majority of accidents.

• If the trip is over remote areas, are appropriate The use of personal standard operating procedures (SOPs) is
clothing, water, and survival gear onboard in the event one way to manage external pressures. The goal is to supply a
of a forced landing? release for the external pressures of a flight. These procedures
include but are not limited to:
• If the trip includes flying over water or unpopulated
areas with the chance of losing visual reference to the • Allow time on a trip for an extra fuel stop or to make
horizon, the pilot must be prepared to fly IFR. an unexpected landing because of weather.

• Check the airspace and any temporary flight restriction • Have alternate plans for a late arrival or make backup
(TFRs) along the route of flight. airline reservations for must-be-there trips.

Nighttime • For really important trips, plan to leave early enough
Night flying requires special consideration. so that there would still be time to drive to the
destination.
• If the trip includes flying at night over water or
unpopulated areas with the chance of losing visual • Advise those who are waiting at the destination that
reference to the horizon, the pilot must be prepared the arrival may be delayed. Know how to notify them
to fly IFR. when delays are encountered.

• Will the flight conditions allow a safe emergency • Manage passengers’ expectations. Make sure
landing at night? passengers know that they might not arrive on a firm
schedule, and if they must arrive by a certain time,
• Preflight all aircraft lights, interior and exterior, for they should make alternative plans.
a night flight. Carry at least two flashlights—one for
exterior preflight and a smaller one that can be dimmed • Eliminate pressure to return home, even on a casual
and kept nearby. day flight, by carrying a small overnight kit containing
prescriptions, contact lens solutions, toiletries, or other
E = External Pressures necessities on every flight.
External pressures are influences external to the flight that
create a sense of pressure to complete a flight—often at the The key to managing external pressure is to be ready for
expense of safety. Factors that can be external pressures and accept delays. Remember that people get delayed when
include the following: traveling on airlines, driving a car, or taking a bus. The pilot’s
goal is to manage risk, not create hazards. [Figure 17-6]
• Someone waiting at the airport for the flight’s
arrival.

• A passenger the pilot does not want to disappoint.

• The desire to demonstrate pilot qualifications.

17-9

Pilot Aircraft
A pilot must continually make decisions about competency, A pilot will frequently base decisions on the evaluations of the
condition of health, mental and emotional state, level of fatigue, airplane, such as performance, equipment, or airworthiness.
and many other variables. For example, a pilot may be called
early in the morning to make a long flight. If a pilot has had only During a preflight, a pilot noticed a small amount of oil dripping
a few hours of sleep and is concerned that the congestion from the bottom of the cowling. Although the quantity of oil
being experienced could be the onset of a cold, it would be seemed insignificant at the time, the pilot decided to delay the
prudent to consider if the flight could be accomplished safely. takeoff and have a mechanic check the source of the oil.
The pilot’s good judgment was confirmed when the mechanic
A pilot had only 4 hours of sleep the night before being asked found that one of the oil cooler hose fittings was loose.
by the boss to fly to a meeting in a city 750 miles away. The
reported weather was marginal and not expected to improve. External Pressures
After assessing fitness as a pilot, it was decided that it would The interaction between the pilot, airplane, and the environment
not be wise to make the flight. The boss was initially unhappy, is greatly influenced by the purpose of each flight operation.
but later convinced by the pilot that the risks involved were The pilot must evaluate the three previous areas to decide on
unacceptable. the desirability of undertaking or continuing the flight as planned.
It is worth asking why the flight is being made, how critical is it to
Environment maintain the schedule, and is the trip worth the risks?
This encompasses many elements not pilot or airplane related.
It can include such factors as weather, air traffic control, On a ferry flight to deliver an airplane from the factory, in
navigational aids (NAVAIDS), terrain, takeoff and landing marginal weather conditions, the pilot calculated the
areas, and surrounding obstacles. Weather is one element that groundspeed and determined that the airplane would arrive at
can change drastically over time and distance. the destination with only 10 minutes of fuel remaining. The pilot
was determined to keep on schedule by trying to “stretch” the
A pilot was landing a small airplane just after a heavy jet had fuel supply instead of landing to refuel. After landing with low
departed a parallel runway. The pilot assumed that wake fuel state, the pilot realized that this could have easily resulted
turbulence would not be a problem since landings had been in an emergency landing in deteriorating weather conditions.
performed under similar circumstances. Due to a combination This was a chance that was not worth taking to keep the
of prevailing winds and wake turbulence from the heavy jet planned schedule.
drifting across the landing runway, the airplane made a hard
landing. The pilot made an error when assessing the flight
environment.

Figure 17-6. The PAVE checklist. Clearly, this is not only an inaccurate inference, it is
impossible. Pilots are drawn from the general population and
Human Behavior exhibit all types of personality traits. Thus, it is important that
good decision-making skills be taught to all pilots.
Studies of human behavior have tried to determine an
individual’s predisposition to taking risks and the level of Historically, the term “pilot error” has been used to describe
an individual’s involvement in accidents. In 1951, a study an accident in which an action or decision made by the
regarding injury-prone children was published by Elizabeth pilot was the cause or a contributing factor that led to the
Mechem Fuller and Helen B. Baune, of the University of accident. This definition also includes the pilot’s failure
Minnesota. The study was comprised of two separate groups to make a correct decision or take proper action. From a
of second grade students. Fifty-five students were considered broader perspective, the phrase “human factors related” more
accident repeaters and 48 students had no accidents. Both aptly describes these accidents. A single decision or event
groups were from the same school of 600 and their family does not lead to an accident, but a series of events and the
demographics were similar. resultant decisions together form a chain of events leading
to an outcome.
The accident-free group showed a superior knowledge
of safety, were considered industrious and cooperative In his article “Accident-Prone Pilots,” Dr. Patrick R. Veillette
with others, but were not considered physically inclined. uses the history of “Captain Everyman” to demonstrate how
The accident-repeater group had better gymnastic skills, aircraft accidents are caused more by a chain of poor choices
were considered aggressive and impulsive, demonstrated rather than one single poor choice. In the case of Captain
rebellious behavior when under stress, were poor losers, and Everyman, after a gear-up landing accident, he became
liked to be the center of attention. One interpretation of this involved in another accident while taxiing a Beech 58P
data—an adult predisposition to injury stems from childhood Baron out of the ramp. Interrupted by a radio call from the
behavior and environment—leads to the conclusion that
any pilot group should be comprised only of pilots who are
safety-conscious, industrious, and cooperative.

17-10

dispatcher, Everyman neglected to complete the fuel cross- • Are impulsive rather than methodical and disciplined,
feed check before taking off. Everyman, who was flying both in their information gathering and in the speed
solo, left the right-fuel selector in the cross-feed position. and selection of actions to be taken.
Once aloft and cruising, he noticed a right roll tendency
and corrected with aileron trim. He did not realize that both • A disregard for or under utilization of outside sources
engines were feeding off the left wing’s tank, making the of information, including copilots, flight attendants,
wing lighter. flight service personnel, flight instructors, and air
traffic controllers.

After two hours of flight, the right engine quit when The Decision-Making Process
Everyman was flying along a deep canyon gorge. While he
was trying to troubleshoot the cause of the right engine’s An understanding of the decision-making process provides
failure, the left engine quit. Everyman landed the aircraft on the pilot with a foundation for developing ADM and SRM
a river sand bar but it sank into ten feet of water. skills. While some situations, such as engine failure, require
an immediate pilot response using established procedures,
Several years later Everyman flew a de Havilland Twin Otter there is usually time during a flight to analyze any changes
to deliver supplies to a remote location. When he returned to that occur, gather information, and assess risk before reaching
home base and landed, the aircraft veered sharply to the left, a decision.
departed the runway, and ran into a marsh 375 feet from the
runway. The airframe and engines sustained considerable Risk management and risk intervention is much more than
damage. Upon inspecting the wreck, accident investigators the simple definitions of the terms might suggest. Risk
found the nose wheel steering tiller in the fully deflected management and risk intervention are decision-making
position. Both the after takeoff and before landing checklists processes designed to systematically identify hazards,
required the tiller to be placed in the neutral position. assess the degree of risk, and determine the best course of
Everyman had overlooked this item. action. These processes involve the identification of hazards,
followed by assessments of the risks, analysis of the controls,
Now, is Everyman accident prone or just unlucky? Skipping making control decisions, using the controls, and monitoring
details on a checklist appears to be a common theme in the the results.
preceding accidents. While most pilots have made similar
mistakes, these errors were probably caught prior to a mishap The steps leading to this decision constitute a decision-
due to extra margin, good warning systems, a sharp copilot, or making process. Three models of a structured framework
just good luck. What makes a pilot less prone to accidents? for problem-solving and decision-making are the 5-P, the 3P,
the 3 with CARE and TEAM, the OODA, and the DECIDE
The successful pilot possesses the ability to concentrate, models. They provide assistance in organizing the decision
manage workloads, monitor and perform several simultaneous process. All these models have been identified as helpful to
tasks. Some of the latest psychological screenings used the single pilot in organizing critical decisions.
in aviation test applicants for their ability to multitask,
measuring both accuracy, as well as the individual’s ability SRM and the 5P Check
to focus attention on several subjects simultaneously. The SRM is about how to gather information, analyze it, and make
FAA oversaw an extensive research study on the similarities decisions. Learning how to identify problems, analyze the
and dissimilarities of accident-free pilots and those who were information, and make informed and timely decisions is not
not. The project surveyed over 4,000 pilots, half of whom as straightforward as the training involved in learning specific
had “clean” records while the other half had been involved maneuvers. Learning how to judge a situation and “how to
in an accident. think” in the endless variety of situations encountered while
flying out in the “real world” is more difficult.
Five traits were discovered in pilots prone to having
accidents. These pilots: There is no one right answer in ADM, rather each pilot is
expected to analyze each situation in light of experience
• Have disdain toward rules. level, personal minimums, and current physical and mental
readiness level, and make his or her own decision.
• Have very high correlation between accidents on their
flying records and safety violations on their driving SRM sounds good on paper, but it requires a way for pilots
records. to understand and use it in their daily flights. One practical
application is called the “Five Ps (5 Ps)” [Figure 17-7] The
• Frequently fall into the “thrill and adventure seeking”
personality category.

17-11

The SRM Five “P” Check The second easiest point in the flight to make a critical safety
decision is just prior to takeoff. Few pilots have ever had to
The Plan make an “emergency takeoff”. While the point of the 5P
The Plane check is to help the pilot fly, the correct application of the
The Pilot 5P before takeoff is to assist in making a reasoned go no-go
The Passengers decision based on all the information available. That decision
The Programming will usually be to “go,” with certain restrictions and changes,
but may also be a “no-go.” The key point is that these two
FhFiaiggsuusrrieeg1n17i6f-i-7c1.a5n.TtIhlalepupFstlirivcaeatetPisoctnhheteocuktshleiosots.ef The Five-P checklist, which points in the process of flying are critical go no-go points on
using onboard management each and every flight.

5syPsstecmosn. sist of “the Plan, the Plane, the Pilot, the Passengers, The third place to review the 5 Ps is at the mid point of the
flight. Often, pilots may wait until the Automated Terminal
and the Programming.” Each of these areas consists of a set of information Service (ATIS) is in range to check weather, yet
at this point in the flight many good options have already
challenges and opportunities that face a single pilot. And each passed behind the aircraft and pilot. Additionally, fatigue
and low-altitude hypoxia serve to rob the pilot of much of
can substantially increase or decrease the risk of successfully his or her energy by the end of a long and tiring flight day.
This leads to a transition from a decision-making mode to an
completing the flight based on the pilot’s ability to make acceptance mode on the part of the pilot. If the flight is longer
than 2 hours, the 5P check should be conducted hourly.
informed and timely decisions. The 5 Ps are used to evaluate
The last two decision points are just prior to descent into the
the pilot’s current situation at key decision points during the terminal area and just prior to the final approach fix, or if
VFR just prior to entering the traffic pattern, as preparations
flight, or when an emergency arises. These decision points for landing commence. Most pilots execute approaches with
the expectation that they will land out of the approach every
include, preflight, pretakeoff, hourly or at the midpoint of time. A healthier approach requires the pilot to assume that
changing conditions (the 5 Ps again) will cause the pilot to
the flight, pre-descent, and just prior to the final approach divert or execute the missed approach on every approach.
This keeps the pilot alert to all manner of conditions that
fix or for visual flight rules (VFR) operations, just prior to may increase risk and threaten the safe conduct of the flight.
Diverting from cruise altitude saves fuel, allows unhurried
entering the traffic pattern. use of the autopilot, and is less reactive in nature. Diverting
from the final approach fix, while more difficult, still allows
The 5 Ps are based on the idea that the pilots have essentially the pilot to plan and coordinate better, rather than executing
five variables that impact his or her environment and that can a futile missed approach. Let’s look at a detailed discussion
cause the pilot to make a single critical decision, or several of each of the Five Ps.
less critical decisions, that when added together can create
a critical outcome. These variables are the Plan, the Plane, The Plan
the Pilot, the Passengers, and the Programming. This concept
stems from the belief that current decision-making models The “Plan” can also be called the mission or the task. It
tended to be reactionary in nature. A change has to occur and contains the basic elements of cross-country planning,
be detected to drive a risk management decision by the pilot. weather, route, fuel, publications currency, etc. The “Plan”
For instance, many pilots use risk management sheets that are should be reviewed and updated several times during the
filled out by the pilot prior to takeoff. These form a catalog course of the flight. A delayed takeoff due to maintenance,
of risks that may be encountered that day and turn them into fast moving weather, and a short notice TFR may all radically
numerical values. If the total exceeds a certain level, the flight alter the plan. The “plan” is not only about the flight plan,
is altered or cancelled. Informal research shows that while but also all the events that surround the flight and allow the
these are useful documents for teaching risk factors, they are pilot to accomplish the mission. The plan is always being
almost never used outside of formal training programs. The updated and modified and is especially responsive to changes
5P concept is an attempt to take the information contained in in the other four remaining Ps. If for no other reason, the 5P
those sheets and in the other available models and use it.

The 5P concept relies on the pilot to adopt a “scheduled”
review of the critical variables at points in the flight where
decisions are most likely to be effective. For instance, the
easiest point to cancel a flight due to bad weather is before the
pilot and passengers walk out the door and load the aircraft.
So the first decision point is preflight in the flight planning
room, where all the information is readily available to make
a sound decision, and where communication and Fixed
Base Operator (FBO) services are readily available to make
alternate travel plans.

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check reminds the pilot that the day’s flight plan is real life highly capable single-engine aircraft has entered into a very
and subject to change at any time. personal relationship with the passengers. In fact, the pilot
and passengers sit within an arm’s reach all of the time.
Obviously weather is a huge part of any plan. The addition
of datalink weather information give the advanced avionics The desire of the passengers to make airline connections or
pilot a real advantage in inclement weather, but only if important business meetings easily enters into this pilot’s
the pilot is trained to retrieve, and evaluate the weather in decision-making loop. Done in a healthy and open way, this
real time without sacrificing situational awareness. And of can be a positive factor. Consider a flight to Dulles Airport
course, weather information should drive a decision, even and the passengers, both close friends and business partners,
if that decision is to continue on the current plan. Pilots of need to get to Washington, D.C., for an important meeting.
aircraft without datalink weather should get updated weather The weather is VFR all the way to southern Virginia then turns
in flight through a Flight Service Station (FSS) and/or Flight to low IFR as the pilot approaches Dulles. A pilot employing
Watch. the 5P approach might consider reserving a rental car at an
airport in northern North Carolina or southern Virginia to
The Plane coincide with a refueling stop. Thus, the passengers have a
Both the “plan” and the “plane” are fairly familiar to most way to get to Washington, and the pilot has an out to avoid
pilots. The “plane” consists of the usual array of mechanical being pressured into continuing the flight if the conditions
and cosmetic issues that every aircraft pilot, owner, or do not improve.
operator can identify. With the advent of advanced avionics,
the “plane” has expanded to include database currency, Passengers can also be pilots. If no one is designated as pilot
automation status, and emergency backup systems that were in command (PIC) and unplanned circumstances arise, the
unknown a few years ago. Much has been written about single decision-making styles of several self-confident pilots may
pilot IFR flight both with and without an autopilot. While this come into conflict.
is a personal decision, it is just that—a decision. Low IFR
in a non-autopilot equipped aircraft may depend on several Pilots also need to understand that non-pilots may not
of the other Ps to be discussed. Pilot proficiency, currency, understand the level of risk involved in the flight. There is
and fatigue are among them. an element of risk in every flight. That is why SRM calls it
risk management, not risk elimination. While a pilot may feel
The Pilot comfortable with the risk present in a night IFR flight, the
Flying, especially when used for business transportation, passengers may not. A pilot employing SRM should ensure
can expose the pilot to high altitude flying, long distance the passengers are involved in the decision-making and given
and endurance, and more challenging weather. An advanced tasks and duties to keep them busy and involved. If, upon a
avionics aircraft, simply due to their advanced capabilities can factual description of the risks present, the passengers decide
expose a pilot to even more of these stresses. The traditional to buy an airline ticket or rent a car, then a good decision has
“IMSAFE” checklist (see page 17-6) is a good start. generally been made. This discussion also allows the pilot
to move past what he or she thinks the passengers want to
The combination of late night, pilot fatigue, and the effects do and find out what they actually want to do. This removes
of sustained flight above 5,000 feet may cause pilots to self-induced pressure from the pilot.
become less discerning, less critical of information, less
decisive and more compliant and accepting. Just as the most The Programming
critical portion of the flight approaches (for instance a night The advanced avionics aircraft adds an entirely new
instrument approach, in the weather, after a 4-hour flight) the dimension to the way GA aircraft are flown. The electronic
pilot’s guard is down the most. The 5P process helps a pilot instrument displays, GPS, and autopilot reduce pilot
recognize the physiological situation at the end of the flight workload and increase pilot situational awareness. While
before takeoff, and continues to update personal conditions programming and operation of these devices are fairly simple
as the flight progresses. Once risks are identified, the pilot is and straightforward, unlike the analog instruments they
in an infinitely better place to make alternate plans that lessen replace, they tend to capture the pilot’s attention and hold it
the effect of these factors and provide a safer solution. for long periods of time. To avoid this phenomenon, the pilot
should plan in advance when and where the programming
The Passengers for approaches, route changes, and airport information
One of the key differences between CRM and SRM is gathering should be accomplished as well as times it should
the way passengers interact with the pilot. The pilot of a not. Pilot familiarity with the equipment, the route, the local

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air traffic control environment, and personal capabilities vis- of risk depends on a number of other factors, such as pilot

à-vis the automation should drive when, where, and how the training and experience, aircraft equipment and fuel capacity,

automation is programmed and used. and others.

The pilot should also consider what his or her capabilities In the third step, the goal is to perform by taking action to
are in response to last minute changes of the approach (and eliminate hazards or mitigate risk, and then continuously
the reprogramming required) and ability to make large- evaluate the outcome of this action. With the example of low
scale changes (a reroute for instance) while hand flying the ceilings at destination, for instance, the pilot can perform
aircraft. Since formats are not standardized, simply moving good ADM by selecting a suitable alternate, knowing where
from one manufacturer’s equipment to another should give to find good weather, and carrying sufficient fuel to reach
the pilot pause and require more conservative planning and it. This course of action would mitigate the risk. The pilot
decisions. also has the option to eliminate it entirely by waiting for
better weather.
The SRM process is simple. At least five times before and
during the flight, the pilot should review and consider the “Plan, Once the pilot has completed the 3P decision process and
the Plane, the Pilot, the Passengers, and the Programming” selected a course of action, the process begins anew because
and make the appropriate decision required by the current now the set of circumstances brought about by the course of
situation. It is often said that failure to make a decision is a action requires analysis. The decision-making process is a
decision. Under SRM and the 5 Ps, even the decision to make continuous loop of perceiving, processing and performing.
no changes to the current plan, is made through a careful
consideration of all the risk factors present. With practice and consistent use, running through the 3P
cycle can become a habit that is as smooth, continuous, and
Perceive, Process, Perform (3P) automatic as a well-honed instrument scan. This basic set of
The Perceive, Process, Perform (3P) model for ADM offers practical risk management tools can be used to improve risk
a simple, practical, and systematic approach that can be used management. The 3P model has been expanded to include the
during all phases of flight. To use it, the pilot will: CARE and TEAM models which offers pilots another way
to assess and reduce risks associated with flying.
• Perceive the given set of circumstances for a flight.
Perceive, Process, Perform with CARE and TEAM
• Process by evaluating their impact on flight safety. Most flight training activities take place in the “time-critical”
timeframe for risk management. Figures 17-8 and 17-9
• Perform by implementing the best course of action. combine the six steps of risk management into an easy-to-
remember 3P model for practical risk management: Perceive,
In the first step, the goal is to develop situational awareness Process, Perform with the CARE and TEAM models. Pilots
by perceiving hazards, which are present events, objects, or can help perceive hazards by using the PAVE checklist
circumstances that could contribute to an undesired future of: Pilot, Aircraft, enVironment, and External pressures.
event. In this step, the pilot will systematically identify and They can process hazards by using the CARE checklist
list hazards associated with all aspects of the flight: pilot, of: Consequences, Alternatives, Reality, External factors.
aircraft, environment, and external pressures. It is important Finally, pilots can perform risk management by using
to consider how individual hazards might combine. Consider, the TEAM choice list of: Transfer, Eliminate, Accept, or
for example, the hazard that arises when a new instrument Mitigate. These concepts are relatively new in the GA training
pilot with no experience in actual instrument conditions wants world, but have been shown to be extraordinarily useful in
to make a cross-country flight to an airport with low ceilings lowering accident rates in the world of air carriers.
in order to attend an important business meeting.

In the second step, the goal is to process this information
to determine whether the identified hazards constitute risk,
which is defined as the future impact of a hazard that is not
controlled or eliminated. The degree of risk posed by a given
hazard can be measured in terms of exposure (number of
people or resources affected), severity (extent of possible
loss), and probability (the likelihood that a hazard will cause
a loss). If the hazard is low ceilings, for example, the level

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Pilots can perceive hazards by using the PAVE checklist: EnVironment
Departure and destination airports have long runways.
Pilot Weather is the main hazard. Although it is VFR, it is a typical
Gayle is a healthy and well-rested private pilot with approxi- summer day in the Mid-Atlantic region: hot (near 90 °F) hazy
mately 300 hours total flight time. Hazards include her lack of (visibility 7 miles), and humid with a density altitude of 2,500
overall and cross-country experience and the fact that she has feet. Weather at the destination airport (located in the
not flown at all in two months. mountains) is still IMC, but forecast to improve to visual
meteorological conditions (VMC) prior to her arrival. En route
Aircraft weather is VMC, but there is an AIRMET Sierra for pockets of
Although it does not have a panel-mount GPS or weather IMC over mountain ridges along the proposed route of flight.
avoidance gear, the aircraft—a C182 Skylane with long-range
fuel tanks—is in good mechanical condition with no inoperative External Pressures
equipment. The instrument panel is a standard “six-pack.” Gayle is making the trip to spend a weekend with relatives she
does not see very often. Her family is very excited and has
made a number of plans for the visit.

Pilots can perform risk management by using the TEAM choice list:

Pilot Aircraft
To manage the risk associated with her inexperience and lack To manage risk associated with any doubts about the aircraft’s
of recent flight time, Gayle can: mechanical condition, Gayle can:
• Transfer the risk entirely by having another pilot act as PIC. • Transfer the risk by using a different airplane.
• Eliminate the risk by canceling the trip. • Eliminate the risk by canceling the trip.
• Accept the risk and fly anyway. • Accept the risk.
• Mitigate the risk by flying with another pilot. • Mitigate the remaining (residual) risk through review of

Gayle chooses to mitigate the major risk by hiring a CFI to aircraft performance and careful preflight inspection.
accompany her and provide dual cross-country instruction.
An added benefit is the opportunity to broaden her flying Since she finds no problems with the aircraft’s mechanical
experience. condition, Gayle chooses to mitigate any remaining risk
through careful preflight inspection of the aircraft.

Environment External Pressures
To manage the risk associated with hazy conditions and To mitigate the risk of emotional pressure from family
mountainous terrain, Gayle can: expectations that can drive a “get-there” mentality, Gayle can:
• Transfer the risk of VFR in these conditions by asking an • Transfer the risk by having her co-pilot act as PIC and make

instrument-rated pilot to fly the trip under IFR. the continue/divert decision.
• Eliminate the risk by canceling the trip. • Eliminate the risk by canceling the trip.
• Accept the risk. • Accept the risk.
• Mitigate the risk by careful preflight planning, filing a VFR • Mitigate the risk by managing family expectations and

flight plan, requesting VFR flight following, and using making alternative arrangements in the event of diversion to
resources such as Flight Watch. another airport.

Detailed preflight planning must be a vital part of Gayle’s Gayle and her co-pilot choose to address this risk by agreeing
weather risk mitigation strategy. The most direct route would that each pilot has a veto on continuing the flight, and that they
put her over mountains for most of the trip. Because of the will divert if either becomes uncomfortable with flight conditions.
thick haze and pockets of IMC over mountains, Gayle might Because the destination airport is still IMC at the time of
mitigate the risk by modifying the route to fly over valleys. This departure, Gayle establishes a specific point in the trip—an en
change will add 30 minutes to her estimated time of arrival route VORTAC located between the destination airport and the
(ETA), but the extra time is a small price to pay for avoiding two alternates—as the logical place for her “final” continue/
possible IMC over mountains. Because her destination airport divert decision. Rather than give her family a specific ETA that
is IMC at the time of departure, Gayle needs to establish that might make Gayle feel pressured to meet the schedule, she
VFR conditions exist at other airports within easy driving manages her family’s expectations by advising them that she
distance of her original destination. In addition, Gayle should will call when she arrives.
review basic information (e.g., traffic pattern altitude, runway
layout, frequencies) for these alternate airports. To further
mitigate risk and practice good cockpit resource management,
Gayle should file a VFR flight plan, use VFR flight following,
and call Flight Watch to get weather updates en route. Finally,
basic functions on her handheld GPS should also be practiced.

Figure 17-8. A real-world example of how the 3P model guides decisions on a cross-country trip.

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