PHYSIOLOGICAL RESPONSES OF PILOTS TO 

SEVERE WEATHER FLYING 

Jess M. McKenzie, Ph.D. 

Vincent Fiorica, Ph.D. 

Approved by Released by 

AM 66-41 

~~ J. RoBERT DILLE, M.D. P. v. SIEGEL, M.D. 

CHIEF, CIVIL AEROl\H~DICAL INSTITUTE FEDERAL AIR SuRGEON 

July 1966 

FEDERAL AVIATION AGENCY 

Office of Aviation Medicine 
ACKNOWLEDGMENTS 

The authors express their gratitude to the staff of the National Severe 

Storms Laboratory for their excellent cooperation and to Dr. E~ Kessler and 

Mr. J. T. Lee for their valuable advice. Sincere appreciation is extended to 

Mr. J. Burnham and Mrs. A. Burns for technical advice and to subject 

pilots of the Royal Air Force and the Air Registration Board for their 

participation in these investigations. 

The assistance of Dr. E. A. Higgins, Mr. D. deSteiguer, Mr. R. Moses 

and Miss P. Fowler is gratefully acknowledged. 

Qualified requestors may obtain Aviation :\ledical Reports from Defense Documentation 

Center. The general public may pun·hase from Clearinghouse fot· Federal Scientific 

and Technical Information, U.S. Dept. of Commerce, Springfield, Va. 22151. 
PHYSIOLOGICAL RESPONSES OF PILOTS TO 

SEVERE WEATHER FLYING 

There is little doubt that flying an aircraft in 

or around storms produces some degree of emotional stress. Emotional reactions are o£ course 

modified by the pilot's experience, type o£ aircraft, severity o£ the storm and proximity to 

severe turbulence. It is possible that flying 

through storms might also produce certain 

specific physiological effects other than those associated with emotional stress. For example, 

severe turbulence may be transmitted to the body 

o£ the pilot resulting in difficulties in breathing/" 

vision,2 and inability to make fine adjustments ;

6 

severe buffeting might also result in temporary, i£ 

not permanent, damage to certain organs. 

Pilot experience may be an important £actor 

in the emotional responses to severe weather flying; a highly trained pilot who is unavoidably 

committed to flying in close proximity to a severe 

storm is more able to evaluate the gravity o£ his 

circumstances and is more skilled in the handling 

o£ his aircraft during unusual conditions. For 

these reasons a thorough study o£ pilot reactions 

to severe weather flying should include subjects 

who have had a great deal o£ flying experience 

as well as those who are relatively new to flying. 

It should be pointed out, however, that it is the 

inexperienced pilot who, because o£ his inability 

to evaluate weather data properly, is most likely 

to run afoul o£ severe storms. 

Because o£ the risks involved in in-flight studies 

o£ this type, especially those involving inexperienced pilots, it was decided that preliminary 

baseline studies employing skilled professional 

pilots should first be attempted. An invitation 

to CAMI scientists £rom the Director o£ the 

National Severe Storms Laboratory o£ the United 

States ·weather Bureau, to participate in project 

Rough Rider during the spring o£ 1965, provided a unique opportunity £or studies on experienced test pilots flying high-performance aircraft through drastic weather conditions. During 

the spring, storm build-ups in the Oklahoma area 

1 

are frequent, rapid, and violent. Such storms 

are often accompanied by tornadic winds, lightning and varying amounts and forms o£ precipitation. 

In conducting these studies the fullest cooperation was received £rom personnel o£ the U.S. 

Weather Bureau and scientists £rom the Royal 

Aircraft Establishment (RAE) , Bedford and 

Farnborough, England. Pilots o£ the Royal Air 

Force and the Air Registration Board served as 

subjects £or these studies and their enthusiastic 

cooperation is appreciated. 

METHODOLOGY 

Subjects: Four pilot subjects volunteered £or 

these studies. All 'vere experienced test pilots; 

three were officers o£ the Royal Air Force assigned to the RAE and one was a test pilot £rom 

the Air Registration Board, London. All were 

between the ages o£ 30 and 40 and were in apparent good health. 

Aircraft: The aircraft used £or storm penetration flights was a Scimitar F. MK. 1, a singleseat, twin engine naval interceptor which had 

been modified £or the Rough Rider missions. 

The two perimeter-mission aircraft were both 

Canberras, also modified £or the Rough Rider 

missions. One, a PR MK. 9, is a high altitude 

photo-reconnaissance aircraft which in these 

studies carried a crew o£ three; the other, a B 

MK. 6, carried a crew o£ two. 

Sampling Procedures: Experiments o£ opportunity were performed during May and early 

June, 1965. All samples were taken between 30 

minutes and one hour before take-off time. Subjects were instructed to empty the bladder completely into a clean polyethylene bottle which was 

immediately placed into an ice bath. Each subject was then weighed while wearing only light 

underclothing. Following this, subjects donned 
their flight suits and left the ready-room to file 

flight plans and began pre-flight checks. 

Approximately 30 minutes after each aircraft 

had landed, subjects returned to the ready-room 

and were immediately weighed under conditions 

similar to those of the pre-flight weighing; following this urine was again collected. 

The volume of each sample was recorded and 

one portion of the sample was specially prepared 

for catecholamine assay. These portions were 

placed in vials containing dry sodium metabisulfite ( 0.5 mgjml urine) and frozen. Additional 

portions were also withdrawn and frozen in separate vials for all other analyses. 

Analytical Methods: All analytical results are 

expressed in terms of urinary creatinine output. 

Urinary creatinine output is relatively constant 

in individual subjects and the expression of other 

urine components in units per unit weight of 

creatinine provides an approximately uniform 

reference system. 

Magnesium and calcium were measured by the 

methods of Hill 7• 8 which were slightly modified 

for analyses of urine. 

Sodium and potassium were estimated by the 

standard Technicon Auto-Analyzer method and 

chloride concentration was measured by the method of Cotlove.1 Creatinine concentration was 

measured using a modification of the procedure 

of Pino, et al.10 Total urinary catecholamine 

(CATAM) levels were determined by a semiautomated fluorometric procedure. 5 Levels of 

hemoglobin in urine were estimated by an automated molecular sieve technique.9 

Flight Profiles: In most cases flights of the 

Scimitar involved penetration of storm clouds. 

Two pilots flew these missions. One flight, made 

to test aircraft instruments, did not involve cloud 

penetration; in one other instance, the same subject prepared for a Scimitar mission but the 

flight was cancelled approximately 125 minutes 

following the pre-flight sampling. Both Scimitar 

pilots also served, on several occasions, as pilots 

o-f the Canberra aircraft ( B-6). These aircraft 

flew around storm areas and were used to photograph smoke trails and to conduct a variety of 

radar observations. 

Evaluations of the turbulence encountered by 

each of the Canberras were made from MK. 13 

2 

fatigue meters on board each aircraft. This 

meter records frequency of vertical accelerations 

in excess of pre-set gravitational limits. A "totalized turbulence" was computed for each flight of 

the Canberras by converting the gravitational 

limits of each channel to relative (zero reference) 

gravitational units, multiplying each channel 

value by the frequency of deflections and adding 

the products of all channels regardless of sign. 

Assessments of turbulence for the storm penetration flights were extracted from the pilots' 

reports. 

RESULTS 

Changes in catecholamine (CATAM) output 

during the storm penetration and perimeter 

flights are given in Tables I and III. Average 

change (~) in the CATAM output during the 15 

penetration flights was + 13.7 ng/mg creatinine 

(Subjects A and B, range -14.7 to +58.8 ngjmg 

creatinine). On one occasion (flight :ff: 17) subject B prepared for a penetration flight which 

was subsequently cancelled; the change in 

CAT AM output in a sample taken 125 minutes 

later was +0.6 ng/mg creatinine. During 19 

perimeter flights change in urinary CAT AM 

output average +4.6 ng/mg creatinine (Subjects 

A, B, C, D; range -12.3 to +23.7 ng/mg 

creatinine). 

Urine flow during both Scimitar and Canberra 

missions was relatively stable for each individual. 

In all but two flights ,urine flows ranged between 

0.2 and 0.6 mljm2 jhr. No trends in this variable 

relative to the severity of flight conditions could 

be detected (Tables I, III). 

Variations in the urinary excretion of electrolytes were of such magnitude that no clear 

relationship with the severity of conditions could 

be observed (Tables II, IV). Changes in urinary 

hemoglobin during penetration flights (Table I) 

and storm-perimeter missions (Table III) were 

small and appeared to be independent of the 

severity of turbulence. 

Pre-flight weights of the subjects changed relatively little over the duration of the study. No 

relationship between the weight loss during the 

flights (which represents, under these conditions, 

a loss in body water) and the severity of the 

flight conditions was detected (Tables I, III). 

vVater losses due to thermoregulatory demands 

could not be assessed. 
TABLE I. Physiological Responses of Pilots to Stonn Penetration Flights. 

Urine Total Urine 

Catecholamines Hemoglobin Body Weight 

1-1 (nanogm/mg (!J.g/mg (kilograms) Q) .j.J creatinine) creatinine) 1 l1l l1l ""' . :J: ~--- bO • oj¢ 

0 1-1 0 •.-! d Q) Summarized Pilot Comments z ..:I~ .-I .-I •.-! u .j.J ........ r...r...a d .j.J u .j.J .j.J .j.J .j.J .j.J .j.J .j.JC'j ........ <II 

~ Q) ..c ·~ ~ 

~~ ~ ·~ ~::.;:: QJ OIN .-I 

bO .,...., lbO .j.JbQ lbO lbO .j.JbQ bO ....... d d::O: ::3 •.-! ,Q Q) •.-! 00•.-1 <l Q)•.-1 11l•.-l <l Q) •.-! l1l •.-! <l ·~ Ki •.-! .,-~ ........ 

.-I ::3 I-I.-I 0.-1 I-I.-I 0.-1 I-I.-I 0.-1 1-1 1-1..-1 -e 

r... Cll p.,r.., p.,r.., p.,~ p.,~ p.,r.., p.,~ ;3:'-" P ::3 a ~'-" e:l 

1 A 83.2 68.5 -14.7 0 0 71.62 71.48 0.14 41.2 0,6 - No pirep, Subject's first flight of project, 

2 A 27.8 52.8 +26.1 0 0 71.46 71.33 0.13 35.6 0.4 L Hail encountered, Brief periods of turb. 

3 A 41.4 59.9 +18.5 0 p 0 71.69 171.55 0.14 35,3 1.0 L-M "Number" of penetrations, Occnl hvy rain 

with hail, Canopy misting, 

4 A -- 31.8 -- 0 :J 0 71.63 171.48 0.15 28.0 0.5 L Nine penetrations. Occnl hvy rain. 

Prolonged updrafts encountered. 

5 A 42.7 72.1 +29.4 0 D 0 71.24 170.97 0.27 51.4 0.4 M Nine penetrations. Difficulty in control 

due to buffetin~. Hvy rain wt. snow. 

One lightning s rike, Shock to pilot, 

6 A 71.4 61.2 -10.2 0.7b 0.7 71.63 171.31 0.32 84.8 0.3 - No oireo. 

7 B 34.3 49.4 +15.1 0.1 p.l 0 80.87 ~0.45 0.42 P-21.4 0.5 L Four penetrations. Occnl engine icing. Radio-trans. failure. 

1:.0 8 B 32.7 41.4 + 8.7 0.1 0.1 0 81.12 180.74 0.38 82.2 0.6 M Four penetrations. Hail and wet ppt. Lateral rocking on third penetration. 

9 B 17.9 26.9 + 9.0 0 0.1 fl-O .1 81.14 ~0.74 0.40 96.1 0.6 L No penetrations. Instrument check, clear 

air turb. encountered. 

10 B 28.1 35.9 + 7.8 0.8 0.6 -0.2 80.58 ~0.38 0.20 76.3 0.5 L Three penetrations. No control problems. Strong surf. winds. 

11 B 15.3 38.9 +23.6 0 0.5 H0.5 80.80 80.48 0.32 179.9 0.4 - No pirep. 

12 B 42.1 50.2 + 8.1 0 o. 7 f+O. 7 -- -- -- -- 0.5 M-H Five penetrations. Severe vertical ¥usts. 

Wet ppt with hail. Pitch control di ficult. 

13 B 28.6 817.4 +58.8 o. 3 o. 7 j!.o.4 80.65 ~0.34 0.31 00.5 0.4 M-H Ltn strike, shock to pilot on 1st penetr Difficulties in pitch-roll control. Inciaence 

ind. jammed. Failure of all pres. instr. 

Confusion due to oscillation from autostblr. 

malfunct. Sensation of being close to stall. 

Water in cockpit. Windscreen iced during ldg. 

14 B 31.9 49.0 +17.1 0.5 p.9 ft 0.4 79.94 79. 62 0.32 99.4 0.4 M Subj. flew Canberra earlier on same day. Lateral rocking. Airframe icin~. Windscreen 

icing. Flying accur~cy ~oor. ort engine diff~culties. Four ene rations. 

15 B ~5.1 43.0 - 2.1 0.2 ~.2 0 80.79 80.38 0.41 iJ.20. 9 0.4 L-M Four penetrations. Lateral rocking. Indic. cabin pressure failure. 

16 B 35,0 45.7 +10.7 0.3 P.4 0.1 80.47 8).08 0.39 93.7 0.5 M Eight penetrations. Lateral rocking. 

17 B 32.2, 32.8 + 0.6. 1,.,3 1.7 f+-0.4 81.99 81.71 0.28 71.6 0.9 - Flt. Cancelled. Subject sedentary for 125 

min. 

~ 

--------- -- -~~ ~-~---

*From Pireps; L: light, M: medium, H: heavy 
~ 

Flt 

TABLE II. URINE ELECTROLYTE CONCENTRATIONS OF PILOTS BEFORE AND AFTER STORM PENETRATION FLIGHTS 

(MICROEQUIVALENTS PER MG. CREATININE). 

Sodium Potassium Chloride Magnesium Calcium - --------

Pre- Post- Pre- Post- Pre- Post- Pre- Post- Pre- PostNo Subj Flt Flt b. Flt _.!!L b. Flt _.!!L _A_ Flt _.!!L ~ Flt _.!!L _A_ 

1 A -- 161 -- -- 172 -- 172 155 -17 4 3 -1 -- 14 -- 2 A 89 99 +10 52 34 -18 112 124 +12 6 6 0 11 10 -1 

3 A 88 202 +114 27 29 +2 82 201 +119 4 7 +3 15 23 +8 

4 A -- 104 -- -- 36 -- 93 123 +30 -- 7 -- -- 17 -- 5 A 126 211 +85 46 47 +1 126 177 +51 4 4 0 12 18 6 

6 A -- 67 -- -- 53 -- 108 103 -5 1 3 +2 -- 13 -- 7 B -- 129 -- -- 56 -- 256 146 -110 -- 2 -- -- 6 -- 8 B 120 162 +42 30 41 +11 117 157 +40 3 2 -1 10 6 -4 

9 B -- 99 -- -- 38 -- 117 162 +45 4 4 0 -- 11 -- 10 B 147 144 -3 51 29 -22 119 158 +39 5 5 0 14 9 -5 

11 B 123 118 -5 68 54 -14 191 134 -57 4 3 -1 8 3 -5 

12 B 128 132 +4 61 42 -19 139 152 +13 4 3 -1 6 5 -1 

13 B 136 97 -39 37 29 -8 131 101 -30 5 4 -1 1 9 +8 

14 B 95 113 +18 41 46 +5 93 122 +29 3 3 0 9 9 0 

15 B -- 82 -- -- 33 -- 47 83 +36 3 3 0 -- 2 -- 16 B 122 138 +16 36 36 0 116 143 +27 4 3 -1 4 2 -2 

17 B* 75 135 +60 i 82 48 -34 75 102 +27 2 2 0 5 12 +7 I 

*Flight cancelled; subject sedentary for 125 minutes. 
TABLE III. PHYSIOLOGICAL RESPONSES OF PILOTS FLYING STORM PERIMETER MISSIONS. 

Flt Subj Urine Total Urine Hemoglobin Body Weight Weight Urine Flow Turbulence 

No Catecholamines ~gm/mg Creatinine (Kilograms) Loss During * (nanogm/mg Creatinine gm/M2/Hr Flight 

Pre- Post- Pre- Post- Pre- Post- Me/M2/Min 

Flt Flt 6. Flt Flt 6. Flt Flt A 

18 c 31.;0 32.1 + 1.1 0 0 0 77.40 77 .os 0.35 86.0 0.4 23.8 

19 c 44.1 31.8 -12.3 0.6 0.1 -0.5 77.54 77.22 0.32 70.4 0.3 10.6 

20 D 27.3 40.6 +13.3 0 0 0 75.57 75.20 0.37 42.3 0.2 9.7 

21 D 26.6 28.8 + 2.2 0.1 0 -0.1 76.42 75.96 0.46 69.8 0.3 1.4 

22 D 27.4 51.1 +23.7 0 0 0 76.38 76.08 0.30 37.3 0.2 4.2 

23 D 30.0 51.0 +21.0 0.3 0 -0.3 75.94 75.72 0.22 40.4 0.3 5.6 -

24 D 33.6 36.5 + 2.9 0.1 0 -0.1 75.92 75.72 0.20 36.8 0.1 10.1 

en 25 D 27.4 50.7 +23.3 0.1 0 -0.1 -- -- -- -- o.s 4.0 

26 A 28.1 32.7 + 4.6 0.2 0 -0.2 71.63 71.25 0.38 37.3 0.2 23.9 

27 A 35.4 44.8 + 9.4 -- 0 -- 71.19 70.92 0.27 51.4 0.3 48.6 

28 B 32.9 37.1 + 4. 7 0.1 0.2 -0.1 80.65 80.00 0.65 108.1 0.3 4.9 

29 B 41.6 51.4 + 9.8 0 1.6 +1.6 81.00 80.32 0.68 168.8 0.6 -- 30 c 34.7 24.9 - 9.8 0 0 0 77 0 70 77.28 0.42 81.2 0.4 10.8 

31 c -- 32.0 -- -- 0 -- -- -- -- -- -- 11.9 

32 c 33.0 30.0 - 3.0 0 0 0 77.94 77 .so 0.44 80.3 0.4 3.5 

33 c 39.4 35.3 - 4.1 0 0.6 +0.6 77.75 77.46 0.29 54.4 0.4 24.0 

34 c 30.8 32.3 + 1.5 0 0 0 78.30 78.00 0.30 42.6 0.3 18.5 

35 c 32.9 27.3 - 5.6 0 0.1 +0.1 78.43 78.11 0.32 52.1 o.s 2.1 

36 c 37.9 33.2 - 4.7 0 0 0 77.45 77.24 0.21 40.6' 0.4 4.9 
'Flt 

~ Subj 

18 c 

19 c 

20 D 

21 D 

22 D 

23 D 

24 D 0) 

25 D 

26 A 

27 A 

28 B 

29 B 

30 c 

31 c 

32 c 

33 c 

34 c 

35 c 

36 c 

TABLE ,IV. URINE ELECTROLYTE CONCENTRATIONS OF PILOTS BEFORE AND AFTER STORM PERIMETER MISSIONS 

(MICROEQUIVALENTS PER MG. CREATININE). 

Sodium Potassium Chloride Magnesium Calcium 

Pre- Post- Pre- Post- Pre- Post- Pre- Post- Pre- PostFlt Flt t,. Flt Flt t,. Flt _ill_ t,. Flt ...!!!... t,. [lt Flt tJ. --- 66 104 +38 33 51 +18 129 126 -3 7 5 -2 1 10 -1 

179 88 -89 70 52 -18 203 108 -95 4 4 0 3 8 -5 

67 80 +13 56 51 -5 91 127 +36 4 2 -2 1 3 +2 

130 128 -2 61 75 +14 145 143 -2 3 2 -1 3 8 +5 

59 64 +5 74 74 0 87 73 -14 2 2 0 2 4 +2 

95 90 -5 49 78 +29 84 131 +47 3 '2 -1 9 9 0 

46 44 -2 57 144 +87 66 88 +22 2 1 -1 5 3 -2 

55 102 +47 55 76 +21 78 111 +33 3 2 -1 1 0 -1 

-- 83 -- -- 42 -- 70 94 +24 3 5 +2 r- 2 -- -- 99 -- -- 41 -- 78 118 +40 4 3 -1 - 12 -- 126 120 -6 53 42 -11 154 123 -31 4 2 -2 0 8 -2 

190 123 -67 69 50 -19 195 128 -67 4 3 -1 1 10 +9 

50 92 +42 40 41 +1 39 86 +47 4 4 0 7 8 +1 

-- 91 -- -- 43 -- -- 99 -- -- 6 -- - 8 -- 129 64 -65 92 55 -37 262 132 -130 4 4 0 6 8 -8 

143 109 -34 57 64 +7 132 149 +17 6 6 0 2 11 -1 

105 78 -27 49 35 -14 97 72 -25 4 4 0 9 7 -2 

149 159 +10 68 60 -8 162 153 -9 7 6 -1 4 11 -3 

221 130 -91 42 44 +2 174 118 -56 5 3 -2 7 8 +1 

() 
DISCUSSION 

Of the physiological responses to severe weather 

flying, changes in the urinary output of catecholamines seemed most closel~ related to the 

severity of weather and the occurence of unusual 

incidents during the ~issions. Various degrees 

of turbulence were experienced during all flights 

but an apparent correlation between intensity 

of turbulence and CAT AM output was noted 

only in missions involving the Scimitar aircraft 

(Fig. 1). It may be significant that for this aircraft evaluations of turbulence intensity were 

made by the pilots, whereas turbulence history 

of the Canberra aircraft was taken from the 

fatigue meter. The CATAM response to turbulence may be mediated more through emotional 

responses than through specific effects of vibration on organ systems. The better correlation of 

subjective eYaluations of turbulence with urinary 

CAT AM changes is consistent with this hypothesis; however, the lmY correlation with fatigue 

meter records in perimeter missions may only 

reflect the narrow range of turbulence to which 

these aircraft were exposed. Extrapolations between these data are to be made with caution. 

110 r-----r---y-----r---y-----

100 

f-

:::> 

ll. 90 f-~ 0 :::> ., o.5 c wo:: 80 z 0 

~ ~ u <( 70 • ...J E 0 0 :I: ~ 

u~ 60 

fw= E • <( • u ., 

~ 0 50 ...J 0. 0 0 <( ., 0 f- E 0 0 0 f- ~ 40 

"' 0 w g z " 30 • 

: I -

o::~ c I SUBJECT A 0 :::> SUBJECT B 

20 

LIGHT LIGHT TO MODERATE I MODERATE I HEAVY 

MODERATE TO HEAVY 

TURBULENCE INTENSITY (PILOT REPORT) 

FmrRE 1. Relationship between urinary total catecholamine output during the penetration flights and the 

pilots' assessment of the turbulence encountered. 

Although it is not possible to separate the turbulence effects from other vagaries of the flights 

(as reported by the pilots) certain missions :i.~ 

which unusual incidents occurred were also ac7 

companied by large increases in the CATAM output. In flight number 13, for example, serious 

mechanical difficulties were encountered in addition to a lightning strike which produced a shock 

to the pilot. The urinary output of catecholamines increased during this flight by nearly 60 

ngjmg creatinine. During flight number 9, this 

same subject flew a routine instrument check; 

CAT AM output increased only 9 ngjmg creatinine. 

W"hile these data may provide some information on the stresses incurred during severe 

weather flying, some peculiar responses are difficult to interpret. For example, of eight flights 

made by subject C in the Canberra aircraft, the 

CAT AM output decreased during flight on six 

occasions. During the two flights for this subject in which an increase occurred, the change 

was slight (approximately 1 ngjmg creatinine). 

It may be that this subject '""as somewhat appre; 

hensiYe about his flights or perhaps the preflight circumstances were more stimulating than 

actual flying. The use of psychological tests in 

conjunction with catecholamine studies might 

clarify these results. 

In the interpretation of CATAM data as indices of stress one precaution should be noted: 

the response of sympathoadrenal systems to stress 

may be significantly retarded by hypocapnia,11 

thus hyperventilation. if this response occurred 

during certain flights (subject en, may have depressed CA TAM release. 

During the present studies the concentrations 

of hemoglobin in urine were measured with a 

new ultra-sensit_iYe method. This technique was 

developed for studies of physiological variations 

in hemoglobin output rather than for detection of 

gross pathological changes. Leakage of small 

amounts of hemoglobin into the urine may be 

conc;idered as reYersible and non-pathological 

findings; Emerson, et al 3 demonstrated that leakage of large amounts of hemoglobin and intact 

erythroplastids into the urine (resulting from 

partial occulsion of the renal Yein) was completely reYersible. Slight elevations in urinary 

hemoglobin may reflect minor fluctuations in 

renal Yenous pressure or perhaps failure of renal 

tubular reabsorption. The significance of these 

changes cannot be assessed as this time, but the 

phenomenon deserns further study. 

Although other physiological measurements 

made during this study did not reflect the stress-
ful circumstances encountered, it is possible that 

the characteristics of the testing situation may 

have obscured some subtle changes in those parameters. For example, water loss due to emotional 

sweating may be related to sympathoadrenal 

activity, but no relationship between total water 

loss and urinary CATAM output could be detected in the present study. vV ater losses due 

to thermoregulatory demands could have far exceeded the losses due to emotional sweating; thus, 

total water loss would relate more closely with 

thermal load than with sympathetic activity. 

From the present study it may be concluded 

that severe weather flying can be stressful even 

in highly trained and experienced pilots. Furthermore, the turbulence component of severe 

weather seems to be directly associated with the 

level of sympathoadrenal response if turbulence 

is evaluated in terms of the pilots' assessment 

of it. 

REFERENCES 

1. CoTLOVE, E., TRANTHA:II, H. V., and BowMAN, R. L.: 

An Instrument and ~Iethod for Automatic, Rapid, 

Accurate and Sensitive Titration of Chloride in Biological Samples. J. Lab. Clin. :\Ied., 51: 461-468, 

1958. 

2. DRAZIN, D. H.: Effects of Low Frequency HighAmplitude Whole-Body Vibration on Visual Acuity. 

FPRC Memo 128 Xov., 1959, Air Ministry (England). 

3. EMERsoN, T. E. et al.: The Development of Reversible Hematuria and Oliguria following Elevation of 

Renal Venous Pressure. CARl Report 63-1, January, 1963. 

4. ERNSTING, J .. : Respiratory Effects of Whole-Body 

Vibration. I<'PRC Rept. X 1164 May, 1961, Air 

Ministry (England) . 

5. FIORICA, V. : An Improved Semi-Automated Procedure for Fluorometric Determination of Plasma Catecholamines. Clin. Chem. Acta. 12 : 198-205, 1965. 

G. GARRILr., R. A., and SNYDER, F. w. : Preliminary 

Study of Aircrew Tolerance to Low Frequency Verti8 

cal Vibration. Boeing Airplane Co. Document No. 

D3-1189, 1957. 

7. HILL, J. B.: An Automated Fluorometric Method for 

the Determination of Serum :\fagnesium. Ann. N. Y. 

Acad. Sci., 102 : 108-117, 1962. 

8. HILL, J. B.: Automated Fluorometric Method for 

Determination pf Serum Calcium. Clin. Chern. 11 : 

122-130, 1965. 

9. :\ICKENZIE, J. :\1., FOWLER, P. R., and FIORICA, V. ; 

Semi-Automated ~Ieasurements of Hemoglobin and 

Total Protein in L'rine. Anal. Biochem., 16: 139-148, 

196ti. 

10. PINO, S., BENOTTI, J., and GARDYNA, H.: An Automated :\fethod for urine Ct·eatinine Which Does Not 

Require a Dialyzer :\Io.dule. Clin. Chem. 11 : 664-666, 

1965. 

11.. FIORICA, V., IA:IIPIETRo, P. F., HIGGINs, E. A., and 

:\los~;s, R.: S~·mpathico-arlrenomedull.ary (SAM) activity in dogs dming acute heat exposure. J. Appl. 

Physiol. 22 ( 1), 1967.. In Press. 

67-3991