VOR

Ist LEG INBOUND TO VOR

guRE 2. Diagram of the flight path used in this study.
First leg was scored after pilot had climbed to altitude
and was inbound to the VOR. The inbound leg of the
holding pattern was flown down the instrument land-
ing system approach to the runway.

s in previous heat studies conducted in this
iboratory,‘*® the subjects wore a headband to
reclude sweat running into the eyes and thereby
terfering with vision.

‘L. Results.

All physiological values in Figures 3 and 4 are
trapolated back to zero time since the first
easurements were made about 214 minutes after
e subject entered the simulator. Fig. 3 shows
‘ep body temperature and skin temperature for
1 runs. Rectal temperature decreased about
(5° C. (0.27° F.) during the “neutral” (25° C.)
n and increased 0.35° C. (0.63° F.) during
posure to 60° C. Skin temperature increased
ring all runs; 1.0° C. (1.8° F.) during the
° ©. run and 5.0° C. (9.0° F.) during the
ttest run.

Heart rate changes are shown in Fig. 4. Heart
ve increased during all runs; the greatest in-
sase was about 25 beats/min during exposure
60° C. and 18 beats/ min at 43° C. During
sosure to 25° C., heart rate increased 10
uts/min.

Some water exchange values are shown in Table
1, Skin and respiratory water losses varied from
182 gms for two hours at 25° C. to 613 gms at
60° C. Control urine output was about the same
for all runs but urine excreted during the ex-
posure varied from 498 gms at 25° C. to 272 gms
at 60° C. Body water loss or dehydration was
not extensive. During the 25° C. run body water
content was essentially unchanged (~45 gms),
while the loss was 108 gms at 43° C. and 360 gms
at 60° C. The effect of temperature on perform-

Tasue 1.—The water exchanges of pilots (12) flying
simulator flights at 25, 43 and 60°C. Total water
exchange is sum of sweat and urine output. Body
water loss is difference of water intake and total water
exchange.*

Exposure Temperature

25.0°C 43.3°C 60.0°C
(77°F) (110°F) (140°F)

Sweat and/or insensible loss

(2 hr period)___-__-----.-- 132 319 613
Urine

Control (1 hr period) _..... 202 201 263

Experimental (1 hr period)_ 498 372 272
Total Water Exchange--...-- 832 892 1148
Water Intake_...----------- 787 784 788
Body Water Loss...-------- 45 108 360

*All values in grams

ance was evaluated by the Wilcoxon matched-
pairs signed-ranks test and is shown in Fig. 5.
Statistical significance occurred on only three
segments of the flight. However, in every
segment of the flight, deviations in performance
at 60° C. were greater than at 25° C. In one
segment (ist leg) the performance decrement at
43° C. was greater than at 60° C. and in one
segment (2nd leg) the decrement at 43° C. was
less than at 25° C. Fig. 5 shows that significant
differences in performance occurred as follows:
1st leg—43° C. worse than 25° C.; Turn 1—48° C.
and 60° C. worse than 25° C.; ILS—60° C. worse
than 25° C. and 48° C,

Fig. 5 also shows that deviations were greater
when the pilot was flying without localizer
guidance. Turn 1, Outbound and Turn 2 were
all off-localizer segments and the deviations were
much greater than for segments where the pilot
was flying on the localizer.



s

. Bioastronautics Data Book

REFERENCES

(Paul Webb, Ed.).
Scientific and Technical Information Division, Na-
tional Aeronautics and Space Administration,
Washington, D.C., 1964.

. Kaufman, W. C.: Human Tolerance Limits for Some

Thermal Environments of Aerospace, AEROSPACE
MED., 34 :889-896, 1963.

Billingham, J, and D. McK. Kerslake: Spectification
for Thermal Comfort in Aircraft Cabins. Flying
Personnel Research Committee, Air Ministry FPRC/
Memo 133, 1960.

. Iampietro, P. F., W. D. Chiles, E. A. Higgins and

H. L. Gibbons: Complex Performance During Ex-
posure to High Temperatures, AEROSPACE MED.,
40 :1331-1835, 1969.

. Chiles, W. D., P. F, Iampietro and E. A, Higgins:

Combined Effects of Altitude and High Temperature
on Complex Performance, HUMAN FACTORS,
14:161-172, 1972.

. Joy, R. J. T.: Heat Stress in Army Pilots Flying

Combat Missions in the Mohawk Aircraft in Vietnam,
AEROSPACE MED., 38 :895-900, 1967.

7.

10.

.

12.

Hardy, J. D. and EB. E. DuBois: The Technic of
Measuring Radiation and Convection, J. NUTR.,
15 :461~475, 1938.

3. Blockley, W. V. and J. Lyman: Studies of Human

Tolerance for Extreme Heat. IV Psychomotor Per-
formance of Pilots as Indicated by a Task Simulat-
ing Aircraft Instrument Flight. AF Tech. Rep. No.
6521, Wright-Patterson AFB, Ohio, 1951.

. Wing, J. F.: A Review of the Effects of High

Ambient Temperatures on Mental Performance.
AMRI-TR-65-102, Wright-Patterson AFB, Ohio,
1965.

Jones, R, D.: Psychomotor Performance Under
Thermal Stress. Proc., Annual AGARD Symposium
for Measurements of Aircrew Performance, Brooks
AFB, Texas, 1969.

Moreland, S. and J. A. Barnes: Exploratory Study
of Pilot Performance During High Ambient Tem-
peratures/Humidity. Proc. Annual AGARD Sym-
posium for Measurements of Aircrew Performance,
Brooks AFB, Texas, 1969.

Chiles, W. D., E. A. Alluisi and 0. S. Adams: Work
Schedules and Performance During Confinement,
HUMAN FACTORS, 10:143-195, 1968.

23523


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TIME, MINUTES

Ficure 4. Heart rates at five minute intervals are plotted during simulator flights at 25, 43 or 60° C. Values are
means of 12 subjects.

ice time may be influenced by the complexity
of the psychomotor test performed by the subject.
The changes in physiology in our studies were
ilways within tolerable ranges and, except for
she exposure to 71° C., had not even approached
dhysiological limits. In addition, performance
Jecrements, in some cases, appeared before any
changes in physiology occurred. The degree of
lehydration in the present study was minimized
since the subjects were hydrated prior to the run.
The largest body water loss (360 gms) was ex-
yerienced during exposure to 60° C. However,
t is possible that flights of this duration (50-60
ninutes) and under the environmental conditions
ised here (43° C.-60° C.) could produce con-
iiderable dehydration if the pilots (subjects) did

not replace any of the body water lost in sweat
and urine. Performance decrements might then
be related to the complex physiological functions
which would be altered because of body water
loss, i.e., increased body temperatures, increased
heart rate (decreased blood volume). The in-
crease in heart rate during exposure to 25° C. was
probably autonomically induced. The excitement,
as well as the difficulty of the flying task, were
probably both involved.

Performance on complex task devices which
require a high degree of alertness, mental func-
tion, muscular coordination and time-sharing of
functions is more readily susceptible to degrada-
tion under adverse conditions than is performance
of simple tasks (i.e., reaction time, meter moni-



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TIME, MINUTES

Ficure 8. Deep body and mean skin temperature are plotted at five minute intervals during simulator flights :
cockpit temperatures of 25, 43 or 60° C. Values are means of 12 subjects.

Iv.

In an earlier study * we showed that perform-
ance on a complex task device which required
time-sharing of different functions was not de-
graded after 30 minutes exposure to 60° C. but
was after 5 minutes at 71° C. Another study ®
corroborated the results at 60° C. The present
study was conducted to extend the earlier studies
to a more direct simulation of the flying task.
The General Aviation Trainer 1 (GAT -1) pro-
vides a very high degree of realism and is there-
fore relevant to the flying situation. Contrary
to the earlier studies, the present study showed
decrements in performance at 60° C, and further
showed that decrements occurred at 43° C. In
our earlier studies + * the subjects were exposed to
hot conditions for 30 minutes plus the time re-
quired both to increase the temperature to the

Discussion.

exposure condition (5-8 minutes) and to retur
the temperature to the neutral condition (1
minutes); the total time of exposure to highe
than-“neutral” temperature was thus 50-f
minutes, with 30 minutes of that time at the e:
posure temperature (60° C. or 71° C.). In tl
present study the subjects were exposed to tl
high temperature for the entire 50 minutes of tl
run so comparisons of the studies are not entire.
in order. However, the fact that decrements
performance were observed at both 43° C. ar
60° C. during the early segments of the run (le
than 30 minutes) indicates that time of exposu
is not the only factor for consideration.

It is also apparent, as it was in our earli
studies‘® and also in the studies of oth
workers, that there is no clear relationsh
between the degree of physiological change a1
performance. Blockley* speculated that tole


when the pilot is involved in the most complex
and critical aspects of the flight segments. Thus,
heat and criticality of operations can be con-
sidered as separate but summative stressors.

The results of this study should have implica-
tions for those flight activities which are con-
ducted in hot areas and which require a great
number of critical maneuvers. One such activity
is agricultural spraying. The flights are at low
levels, require a great deal of skill and alertness,
and are flown under other adverse conditions
than temperature, i.e. possibility of exposure to
agricultural poisons. The pilots of general
aviation aircraft in hot areas of the country may

also be exposed to high temperature before and
during flight and should be aware of the adverse
effects of heat on performance. High ambient
temperatures, in addition to altering physiology
and performance of the pilot also alter perform-
ance characteristics of the aircraft, by increasing
density altitude. Increased runway length is re-
quired ; rate of climb is decreased ; landing speed
is increased ; and maneuverability of the aircraft,
in general, is decreased. The combination of
factors, degraded pilot and aircraft performance,
could be contributory in some general aviation,
and particularly aerial applicator, accidents.



TECHNICAL REPORT STANDARD TITLE PAGE

Ty Report No. 2. Government Accession No. 3. Recipient's Catalog No.
FAA-AM-72-17

4. Title and Subtitle 5. Report Date

HIGH TEMPERATURE AND PERFORMANCE IN A FLIGHT May 1972

TASK SIMULATOR

6. Performing Organization Code

7 huthor(s)p BP, Tampietro, Ph.D., C. E. Melton, Jr., Ph.D}§ Performing Organization Report No.
&, A, Higgins, Ph.D., J. A. Vaughan, B.S., S. M. Hoffmann,
3._E. Funkhouser, B.A., J. T. Saldivar, B.A.

9. Performing Organization Name and Address 10. Work Unit No.
FAA Civil Aeromedical Institute
P. 0. Box 25082 TT. CSntract or Grant No.

Iklahoma City, Oklahoma 73125

13. Type of Report and Period Covered

12. Sponsoring Agency Name ond Address
d£fice of Aviation Medicine
federal Aviation Administration OAM Report
300 Independence Avenue, S.W. 14. Sponsoring Agency Code
Vashington, D.C, 20591

5. Supplementary Notes

York was performed under Task No, AM-B-72-PHY-52.

fneeF tects of high cockpit temperature on physiological responses and performance
were determined on pilots in a general aviation simulator. The pilots (all instru-
ment rated) "flew" an instrument flight while exposed to each of three cockpit temp-|
eratures: 1) 25.0° C. (77°F.), 2) 43.3°C, (110°F.), 3) 60,0°C. (140°F.). Each
flight lasted about 50 minutes. Performance was scored as the deviations in
heading from the pre-determined flight path. Deviations were scored for seven seg-
ments of the flight. Physiological parameters recorded were: heart rate, deep
body temperature, skin temperature and urine output and sweat loss.

Deep body temperature increased 0.35°C.(0.63°F.) during exposure to 60°C. and de-
creased about 0.15°C. (0.27°F.) during the "neutral" (25°C.) run. Skin temperature
increased 1.0°C, (1.8°F.) during the 25°C. rum and 5.0°C. (9,0°F.) during the
hottest run. Heart rate increased 25 beats/min at 60°C., 18 beats/min at 43°C. and
10 beats/min at 25°C, The largest body water loss was 360 gms at 60°C.

There were significant decrements in performance in three segments of the flight.
Performance at 43°C, was degraded over performance at 25°C. during the 1st segment
of flight. Performance at 43 and 60°C. was degraded over performance at 25°C,
during Turn 1. Performance at 60°C. was worse than performance at 25 and 43°C.
during the ILS segment.

Results are discussed in terms of the complexity of the flight segment being "flown,"

Ker rds . 18, Distributior
piyslSfogical responses to heat, Simula+ Availabitity ts unlimited. Document may

tor performance, Water exchanges, Heart| be released to the National Technical

rate, Body temperature, Skin tempera~ Information Service, Springfield,

ture Virginia 22151, for sale to the public.
+ Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages: 22, Price
Unclassified Unclassified 8 $3.00

tm DOT F 1700.7 (e-69)







FF) 25°C (77°F)
43°C (110° F)

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-—HOLDING PATTERN———
FLIGHT SEGMENTS

Fieuse 5. Deviations from a pre-determined flight path for the various segments of simulator flights are plotted
for three exposure temperatures: 25, 43 and 60° C. All values are means of 12 subjects.

toring). Performing an instrument flight in
a simulator can be considered a highly complex
task. The present study indicates that portions
of the flight can be performed with no significant
decrements in performance even during exposure
to high temperature (43° C. and 60° C.). Those
segments seem to be more “routine” and are

associated with straight and level flight after
becoming established on a radial. Performance
on more complex segments of the flight (transi-
tions or off-localizer operations) was adversely
affected by the addition of a stress (exposure to
high temperatures). It is important to point out
that the effects of the heat are most apparent


Fievure 1.

marker) ; entering a holding pattern and execut-
ing the pattern for three complete turns; and
flying an ILS (instrument landing system) ap-
proach to the runway. Performance was scored
as heading deviations from the ideal flight path.
Deviations were measured at 109 equal intervals
along the flight path. The actual flight path was
recorded on an area chart by means of an X-Y
plotter coupled to the simulator.

Figure 1 also shows the instrumentation used
to record physiological parameters. Skin tem-
perature was measured by means of thermo-
couples at seven points on the body (forehead,
chest, thigh, calf, dorsal foot, forearm, and
palm) and recorded on a Honeywell Electronik
16 recorder (C). Mean skin temperature was
calculated according to the formula of Hardy.”

The general aviation simulator used in this study. The trainer has pitch, roll and yaw capabiliti
Explanation of letters in text.

Deep body temperature was measured by
thermistor probe and a YSI Telethermomet
(D). Heart rate was recorded on an Avion!
Electrocardiocorder Model 350 magnetic ta
recorder (E) and displayed simultaneously on
Tektronix oscilloscope (F). All physiologic
parameters were recorded at five-minute interva
In addition to the above, sweat loss (bo
weight) and urine output were measured.

order to insure adequate urine output and
minimize dehydration, each subject drank
ml/kg of water one hour prior to the expe
mental runs. Body weight was measured one hc
before the run and after the run (two hor
elapsed time). Values for sweat loss are the
fore available for the two hour period. Ur:
chemistries will be reported in another pap


HIGH TEMPERATURE AND PERFORMANCE IN A
FLIGHT TASK SIMULATOR

+ Introduction.

The effects of high temperatures on human
erformance in high performance aircraft and
pacecraft have received much attention.1> The
igh temperature problem associated with these
ehicles is one of heat generated primarily by
re great speeds they attain (friction) and not
y environmental heat loading. Relatively little
ttention has been given to the effects of high
mperatures on pilots of relatively slow flying
ireraft where the high temperatures are ambient
uther than frictionally generated. Aerial ap-
lication activities, to some extent general avia-
on activities, and some military flight opera-
ons® are carried out in warm or hot
ivironments where the pilot can be exposed to
considerable environmental heat load. The
lot is exposed to these conditions for variable
ngths of tinie while in his aircraft on the
round as well as during the flight if it is con-
icted at low altitudes. Crop dusting activities
1d some military operations are flown only
)-100 feet above ground level where air tempera-
res are essentially the same as at ground level.
The possibility exists that exposure to high
mperatures may be a contributing factor in
me accidents where human error is suspected as
ing causative.

The purpose of this work was to determine the
‘ects of high cockpit temperatures on perform-
ce of pilots “flying” a general aviation type
nulator.

» Methods.

Thirty-six simulator flights were flown by 12
lot subjects holding current FAA medical cer-
icates and instrument ratings. The pilots were
paid volunteers between ages 32-50, No at-
npt was made to select the subjects on the basis
physical characteristics, number of hours flown,
age.

Each subject reported to the laboratory in the
morning on four consecutive days. The first day
was devoted to orientation and a familiarization
flight in the simulator (General Precision Sys-
tems, Inc., Link General Aviation Trainer 1,
GAT-1, Fig. 1). The next three mornings were
devoted to data collection runs at three tempera-
tures: 25,0° C. (77° F.), 43.8° C. (110° F.), and
60.0° C. (140° F.). Each run lasted about 50
minutes. The order of exposure to the three
temperature conditions was adjusted so that each
temperature was run four times on the first
experimental day, four times on the second day
and four times on the third day, Cockpit
humidity was not controlled but was monitored.
When the cockpit temperature was 25° C., rela-
tive humidity averaged 45%, at 43° C. it was 22%
and at 60° C, it was 11%. Cockpit temperature
was controlled by means of a forced air heater
(5000 watts) mounted above the simulator and
connected to it by a flexible hose (Fig. 1, A). The
hose was attached by slip-rings which allowed the
simulator to turn without twisting the hose. The
temperature in the cockpit was controlled by
varying the output of the heater via a variable
transformer. Air flow was constant but turbulent
and entered the cockpit behind the pilot and also
above his head. Bafiles (B) diverted the air to
all parts of the cockpit without allowing a draft
directly on the pilot. The temperature condition
for the run was already established when the
pilot entered the cockpit.

The flight was made entirely on instruments
and instructions were conveyed by intercom to
the pilot by an observer who served as an air
traffic controller. The flights which were used
for performance evaluation consisted of a stand-
ardized instrument flight plan composed of the
following elements (Fig. 2): flying a course
inbound to a VOR (very high frequency omni-
directional radio range), executing a turn at the
VOR and flying to a LOM (locator, outer