PHYSIOLOGICAL RESPONSES OF LOW-TIME PRIVATE PILOTS TO
CROSS-COUNTRY FLYING

I. Introduction.

A number of studies have been directed toward
describing in physiological or biochemical terms
the compensatory adjustments of people to work
in the aviation environment. The principal
thrust of these studies has been toward under-
standing the mechanisms of fatigue or stress
that, presumably, underlie performance decre-
ments and thus contribute to unsafe operations.
Some studies have been directed toward ways of
relieving the stress of flying.

The study reported here is a continuation of
an earlier study of the physiological responses
of student pilots to flight training, and is di-
rected at identifying the elements that contribute
to the sensation of weariness that is a common
complaint of low-time pilots after cross-country

flying.
II. Methods.

Ten private pilots, all of whom had less than
100 hours of flight experience, were given gen-
eral assignments to fly, on separate days, three
round-trip cross-country flights from Will Rogers
Airport in Oklahoma City, in order, to Dallas
Love Field (320 nautical miles), Kansas City
Municipal Airport (520 NM) and El Paso Inter-
national Airport (960 NM). The flights were
planned to provide approximately 8, 5, and 9
hours of flight time, respectively. All flights
were made in the same airplane, a new Piper
Cherokee 235. One subject quit the project after
the Dallas flight, another did not make the El
Paso flight. All subjects were given four instruc-
tional flights in the project airplane. All flight
planning was done by the subjects; they made
decisions about weather, departure times, etc.
They were only told where to go and to make
the round trip flight in the minimum time con-
sistent with practicality, always maintaining
VFR, and to return to Will Rogers Airport
before sunset.

Subjects collected urine specimens during the
24 hour period surrounding the flights according
to the following schedule: Specimen Number One
was collected upon arising in the morning,
Specimen Number Two was collected one hour
prior to flight, Specimen Number Three was
collected during the period of flight and imme-
diately post-flight, Specimen Number Four was
collected from the time of completion of collec-
tion of the third specimen until bedtime. Speci-
mens number three and four each were pooled
specimens, commonly made up of several void-
ings; the first and second were single voidings.

The urine specimens were acidified with con-
centrated sulfuric acid. Twenty-five ml aliquots
were frozen and stored until they were analyzed
for epinephrine and norepinephrine? and for
creatinine.

Subjects were fitted with steel plate ECG
electrodes positioned on the lateral chest walls
and secured with an elastic strap. The ECG
was amplified and recorded on one channel of
an instrumentation tape recorder.

Voice transmissions were detected by a boom
microphone, amplified and recorded on another
channel of the tape recorder.

The continuously-recorded ECG was reduced
to one-minute heart rates as previously described.”
The voice record was used to identify the various
phases and events of the flights for correlation
with the heart rate.

The subjects took a psychomotor test? and
completed questionnaires about their subjective
feelings before and after each flight. Their
blood pressure was taken at that time.

Ill. Results.

A. Catecholamines: The grouped results show,
for all three flights, an increase of catecholamine
excretion in the second and third specimens with
a slight decline in the fourth specimen from the
third specimen peak. The increase was greatest



REFERENCES

am

. Melton, C. B., M. Hoffmann, and R. H. Delafield:
The Use of A Tranquilizer (Chlordiazepoxide) in
Flight Training. FAA Office of Aviation Medicine
Report No, AM-69-12, 1969.

. Melton, C, E., and M. Wicks: In-flight Physiological
Monitoring of Student Pilots. FAA Office of Avia-
tion Medicine Report No. AM-67-15, 1967.

. Fiorica, V., and R. Moses: Automated Differential

Fluorometric Analysis of Norepinephrine and Epine-

phrine in Blood Plasma and Urine (Submitted for

Publication).

Pino, S., J. Benotti, and H. Gardyna: An Automated

Method for Urine Creatinine Which Does Not Re-

quire a Dialyzer Module, CLIN. CHEM., 11:664-666,

1965.

Melton, C. E., M. Wicks, J. T. Saldivar, J. Morgan,

and F. P. Vance: Physiological Studies on Air

Tanker Pilots Flying Forest Fire Retardant Mis-

sions. FAA Office of Aviation Medicine Report No.

AM-68-26, 1968.

. Fiorica, V., E. A. Higgins, P. F. Iampietro, M, T.
Lategola, and A. W. Davis: Physiological Responses
of Men During Sleep Deprivation, JOUR. APPL.
PHYSIOL, 24 :167-176, 1968.

7, Rowen, B.: Biomedical Monitoring of the X-15 Pro-
gram, AFFTC-IN-61-4, May 1961.

8, Roman, J.: Risk and Responsibility as Factors Af-

fecting Heart Rate in Test Pilots—The Flight Re-

search Program—II, AEROSP. MED., 36:518-528,

1965.

w

cy

»

a

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9. Balke, B., C. E. Melton, and C. Blake: Physiological
Stress and Fatigue in Aerial Missions for the Con-
trol of Forest Fires, AEROSP. MED., 37:221-227,
1966.

10. Roman, J., and L. EK. Lamb: Electrocardiography in
Flight, AEROSP. MED., 33 :527-544, 1962.

11. Roman, J., H. Older, and W. L. Jones: Flight Re-
search Program: VIJ. Medical Monitoring of Navy
Carrier Pilots in Combat, AEROSP. MED., 38 :183-
139, 1967.

12. Lochridge, G. K., H. B. Hale, and E, W. Williams:
Endocrine-Metabolic Responses to Parachuting.
SAM-TR-68-72, August 1968.

18. Hale, H. B., James P. Ellis, and Edgar W. Williams:
Endocrine and Metabolic Changes During a 12-Hour
Simulated Flight, AEROSP. MED., 36 :717-719, 1965.

14. Hale, H. B., Clarence A, Anderson, Edgar W. Wil-
liams, and Emanuel Tanne: Endocrine-Metabolic
Effects of Unusually Long or Frequent Flying Mis-
sions in C-130E or C-135B Aircraft, AEROSP.
MED,., 39 :561-570, 1968.

15. Hale, H. B., and Edgar W. Williams: Endocrine-
Metabolic Response to Sequential Decompression
During Simulated Orbital Flight. SAM-TR-68-63,
June 1968,

16. Hale, H. B., J. C. Duffy, James P. Ellis, and Edgar
W. Williams: Flying Stress in Relation to Flying
Proficiency, AEROSP. MED., 36 :112-116, 1965.



Taste IJ.—Percentages of Maximum and Minimum
Heart Rates Accounted for by Various Phases of
Cross-Country Flights

Percentage of Percentage of

Phase of Flight Maximum Minimum
Heart Rates Heart Rates

Terminal Procedures 73% 30%
OKC 27 15
Unfamiliar Airport 46 15
Enroute 15.5 61
Outbound from OKC 4 42
Inbound to OKC 11.5 19
Other 11.5 8

flights.- Thus, as with catecholamine excretion,
the length of the flight was unrelated to the
heart rate.

C. Blood Pressure: The post-flight systolic
blood pressure was found to range from 98.4%
to 135.8% of the pre-flight systolic pressure.
Ranking of these values for testing revealed, as

KANSAS CITY

1 NOREPINEPHRINE
GEN EPINEPHRINE
9 8 9 6
2266

3

8

a2

$

20

URINARY EXCRETION ng/mg CREATININE
3

SPECIMEN NUMBER

Urinary excretion of norepinephrine and
Grouped data for the Kansas City flight.

Fieure 2.
epinephrine.

Taste III.—Pre- and Post-Flight Blood Pressure

DAL MKC ELP
Subject

Pre- Post Pre- Post, Pre- Post,
118/70 128/78 9 ____- eee ---------- = eee ee
130/74 124/82 130/72 130/80 124/78 122/76
148/86 142/80 148/90 144/82 132/88 152/84
126/80 138/88 130/80 140/80 124/78 144/84
126/86 132/80 132/82 180/800 -.------------------- +--+
106/62 118/68 106/58 128/78 114/60 120/70
140/78 146/82 146/80 144/84 132/78 160/80
154/90 160/94 150/92 148/80 146/88 144/88
118/70 140/78 114/76 130/70 106/70 144/82
110/75 134/66 128/78 142/84 110/78 134/72

with the urine and heart rate values, that there ment over the pre-flight performance. Ranking

was no statistically significant relationship be-
tween blood pressure and the length of the flight.
Pre- and post-flight blood pressures are shown
in Table TIT.

D. Psychomotor Tests: It has been reported
that the fatigue brought on by prolonged sleep-
lessness is reflected by a decrement in psycho-
motor performance? In this study post-flight
psychomotor performance was variable, some-
times declining but commonly showing improve-

of the pre- and post-flight differences again
failed to reveal any statistically valid relation
to the length of flight.

E. Correlations; A grid was constructed upon
which the significance of the relationship of each
physiological and biochemical variable to all
others could be charted. Only random and oc-
casional points of significance were revealed.
Thus, it is concluded that the variables measured
were independent of each other.



in the post flight (number 8) specimens and is
apparent for norepinephrine as well as for epine-
phrine (Figs. 1-3).

The differences in the ratios of the concentra-
tions of each catecholamine in the second, third,
and fourth specimen to the concentration in the
first (resting) specimen for each of the flights
were computed and ranked for nonparametric
statistical testing. Thus, the percentage differ-
ence in catecholamine excretion for each of the
three flights was expressed. There were no points
of significant difference in levels of excretion
between any of the flights. Thus, the duration
of the flights was unrelated to the concentration
or rate of urinary excretion of the catecholamines.

B. Heart Rate: Average values and ranges for
individuals are shown in Table I. It is note-
worthy that in only five cases was the average
heart rate less than 100 beats per minute. Maxi-
mum heart rates ranged from 123 to 180 bpm;
minimum heart rates ranged from 56 to 111
bpm. Table II shows that 73% of the maximum
heart rates occurred during terminal procedures;
27% occurred at Oklahoma City while 46% oc-

DALLAS
[NOREPINEPHRINE
EPINEPHRINE
60, 10 10 10 7
226

50.

40,

30.

20.

URINARY EXCRETION ng/mg CREATININE

—

SPECIMEN NUMBER

a

Fieurs 1. Urinary excretion of norepinephrine and
epinephrine. Grouped data for the Dallas flight.

asin I—Average Heart Rates with Ranges

DALLAS KANSAS CITY EL PASO
Subject
Average Range Percent || Average Range Percent || Average Range _ Percent
Resting Resting Resting

101)

96 (136 82) 131.5 14
98 (127° 84) 107.7 102
113-0 «(146 74) 120.2 ili
129° (170 92) = 107.5 130
108 «(182 83) = 104.8 38
183 (180 111) 147.8 121

(150 83) :121,3 |].-----.-----------------------
(144185) 129.1 95 (123 73) 101.1
(142 80) 118.1 109 (189 84) 116.0
(472 102) 121.5 131 (164 80) 131.0
(185-56) 117.3 109 (1450-76) 112.4
(15488) 117.5 120 (161 87) 120.0

*Recorder malfunction on Dallas flight: Subject left project without making MKC and ELP flights.

**Subject left project without making El Paso flight.

curred at the unfamiliar airports. Sixty-one
percent of the minimum heart rates occurred
during the en route segments with 42% occurring
outbound from Oklahoma City and 19% inbound
to Oklahoma City.

When the
from resting

percentage changes in heart rate
were ranked and comparisons be-
tween flights were made by non-parametric sta-
tistical tests, it was obvious that there was no
statistically significant difference between the


ful en route phase of the return to Oklahoma
City. If that is the case, then the dilution was
not great enough to cause significant differences
in the concentration ‘(or rate of excretion) of
urinary catecholamines for the three flights.

Since the concentrations or excretion rates are
not significantly different, it must be concluded
that the total excretions are different in propor-
tion to the length of the flights (Table V).

It is concluded, therefore, (1) that the level
of stress is essentially equal for the three flights
and is comparatively high. However, by con-
sidering only the level of stress, reflected in the
concentration of catecholamines in the urine,
consideration of the time-dependent factor of
stress is neglected, leading to the conclusion that
(2) the total stress of these flights is an integral
of the level of stress and the time over which it
is applied. It is further concluded (3) that
terminal procedures at the three unfamiliar air-
ports acted as rather powerful stressors of short
duration compared to the duration of the entire
flight.

60.

0.

40

30.

20

URINARY EXCRETION ng/mg CREATININE

EL PASO

[_sNOREPINEPHRINE
GE] EPINEPHRINE

223

SPECIMEN NUMBER

Ficure 3. Urinary excretion of norepinephrine and

epinephrine,

Grouped data for the El Paso flight.



TECHNICAL REPORT STANDARD TITLE PAGE

T. Report No. 2. Government Accession No.

FAA-AM~71-23

3. Recipient’s Catalog No.

4. Title and Subtitle

PHYSIOLOGICAL RESPONSES OF LOW-TIME
PRIVATE PILOTS TO CROSS-COUNTRY FLYING

5. Report Date
April 1971

6. Performing Organizetion Code

7. Author's)

8. Performing Organization Report No.

C. E. Melton, Ph.D.
Vincent Fiorica, Ph.D.

9. Performing Organization Name and Address 10. Work Unit No.
FAA Civil Aeromedical Institute
P. 0. Box 25082 11. Contract or Grant No.

Oklahoma City, Oklahoma 73125

13. Type of Report and Period Covered

12. Sponsoring Agency Name and Address
Office of Aviation Medicine OAM Report
Federal Aviation Administration
800 Independence Avenue, S.W.
Washington, D.C. 20590

14. Sponsoring Agency Code

15. Supplementary Notes

This work was performed under task AM-A-70-PHY-27.

16. Abstract
Various physiological, biochemical, and psychophysiological measurements were
made on low-time private pilots who each flew three cross-country flights.

The round-trip flights were 320, 520, and 960 NM in length. Heart rate was
recorded continuously throughout the flights. Urine, collected for the 24-hour
period surrounding the flights, was differentially analyzed for epinephrine

and norepinephrine. None of the measured parameters changed in proportion to
the length of the flights; however, the level of stress was high when compared
to other types of flying activities. The total stress of such flights must,
therefore, be considered to be in direct proportion to the length of the
flights.

17. Key Words 18. Distribution Statement
Stress, Cross-country flying, Availability is unlimited. Document may
Low-time pilots, Catecholamines, be released to the National Technical
Heart Rate Information Service, Springfield,

Virginia 22151, for sale to the public.

20. Security Classif. (of this page) BI. No. of Pages | 22. Price

Unclassified 6 $3.00

19. Security Classif. (of this report)

Unclassified
Form DOT F 1700.7 (8-69)



Tasux IV—Comparison of Various Pilot Groups’ Physiological and Biochemical Responses

Average
Heart Rate
BPM

NOREPINEPHRINE EPINEPHRINE
pg/100 mg Bg/100 mg
Creatinine Creatinine

X-15 (5)* 154 Parachutists (12)-. - 9.83 Parachutists (12)_. -~ 2,29
This Study. 113 This Study---- - 5.49 Student Pilots (13). - 2.18
Student Pilots (2)- 112 Student Pilots (1) - 5.34 This Study. - 1.64
F-104 (8)- 108 Simulated Flight (13) - 4,84 Forest Fire Bombers (5)... 1.62
Forest Fire Bombers (5)- 105 Forest Fire Bombers (5) 4,03 Simulated Flight (13)----- 1,60
Forest Fire Bombers (9)- 104 Long Flights C-135 (14)-- 3.81 Decompression (15)_-..--- 1,18
Student Pilots (1)--- 103 Decompression (15)_. - 3.74 Long Flights C-135 (14).- 1.16
F-100 (10)------ 99 Simulated Flight (13) - 3.00 Decompression (15)-.. - 0.94
Navy-Combat A~4’s (11) 88 Decompression (15) 2.89 Simulated Flight (18) - 0.79

F-100 (16) - 2.88 F-100 (16) 0.70

Laboratory Personnel (16)- 2.46 Laboratory Personnel (16)- 0, 68

*Numbers in parentheses are literature references.

Iv.

These data demonstrate that cross-country
flying by low-time pilots generates physiological
responses that rank quantitatively near the top
of a spectrum of responses of pilots to a wide
variety of flight tasks (Table IV). It is well-
known that catecholamine excretion normally
rises during the day. The quantities excreted
by these low-time pilots, however, points to the
additive effect of flight activity when compared
to daytime control values from nonflying labora-
tory personnel (Table IV). If the term “stress”
is to be employed in referring to combat and
other hazardous flight activities, then that term
must certainly be applicable to this group of
pilots.

Discussion.

While the excretion of metabolic products in
the urine gives a good quantitative indication of
the body’s response to total activity, the time
resolution is rather poor. The heart rate data
would lead to the conclusion that terminal pro-
cedures at the unfamiliar airports gave rise to
the greatest metabolic response, for those activi-
ties account for 46% of the maximum heart rate
while terminal procedures at the home airport
account for only 27% of the maximum rates.
The terminal activities at Love Field, Kansas
City Municipal Airport, and El Paso Interna-
tional Airport must be considered as short-term
stressors of considerable intensity. It would be
expected that the metabolites produced in re-
sponse to those stressors would be diluted by the
urine produced during the comparatively peace-

‘Taste V.—Mean Total Excretion of Catecholamines (pg) in the Number Three Specimen

DALLAS KANSAS CITY EL PASO
Subject
Number E NE Total E NE Total E NE Total
1 5.1 11.6 16.7
2. 3.7 24.3 28.0 11.8 41.4 53.2
3 4.6 18.1 22.7 4.7 14,7 19.4
4 0.8 3.7 4.5 12.1 63.0 75.1
5. 8.9 5.3 14,2 13.1 21.3 34.4
6. 5.8 17.0 22.8 3.9 24,4 28.3
7. La 19,1 20.2 6.2 14.5 20.7
8. 8.9 17.8 26.7 11.8 31.9 43,7
9 6.8 7.9 14,7 6.2 7.4 13.6
10. 5.7 19.0 24,7 5.6 27.0 32.6
AV--.------ 51 14,4 19.5 8.4 27.3 35.7 8.1 32.6 40.7
SEM--.--.- 0.9 2.2 2.3 1.2 5.6 6.4 1.8 3.0 4.6





ACKNOWLEDGMENTS

The authors wish to thank Mrs. Marlene Hoffman, Ted Saldivar, and
Russell Moses for their technical help and Mrs. Dickie Price and Mrs. Freida
Ditto for typing the manuscript.