DOT/FAA-AM-85-5 

SOME EFFECTS OF ALCOOOL AND SIMULATED ALTITUDE ON 

COMPLEX PERFORMANCE SCORES AND BRFATHALYZER RFADINGS 

William E. Collins, Henry w. Mertens, and E. Amold Higgins 

Civil Aeromedical Institute 

Federal Aviation .Administration 

Cl<lahana City, Cl<lahoma 7 3125 

JULY 1985 

Document is available to the public through the 

National Technical Information Service, 

Springfield, Virginia 22161. 

Prepared for 

U.S. DEPARTMENT OF TRANSPORTATION 

Fed era 1 Aviation .Administration 

Office of Aviation Medicine 

Washington, DC 20591 
NOTICE 

This document is disseminated under the sponsorship of the 

Department of Transportation in the interest of information 

exchange. The United Sta tea Government assumes no liability 

for its contents or use thereof. 
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SOME EFFECTS OF ALCOHOL AND SIMULATED ALTITUDE ON 

COMPLEX PERFORMANCE SCORES AND BREATHALYZER READINGS 

JULY 1985 6 . Performing Organization Code 

f-::----,--:---:------------------------------------------------------l 8. Performing 0 rgan i z ali on Report No. 

7 · Autho r' s) William E. Collins' Henry w. Mertens' and 

E. Arnold Higgins 9 . Performing Organization Name and Address 

FAA Civil Aeromedical Institute 

P.O. Box 25082 

Oklahoma City, Oklahoma 73125 

10 . Work Unit No . (TRAIS) 

11. Contract or Grant No . 

13. Type of Report and Period Covered 

~----------------------~------------------------------~ 12. Sponsoring Agency Name and Address 

Office of Aviation Medicine 

Federal Aviation Administration 

800 Independence Avenue, SW. 

Washington, DC 20591 

15 . Supplementary Notes 

14. Sponsoring Agency Code 

Work was performed under tasks AM-A-82/83-PSY-86 and AM-A-84/85-PSY-94. 

16. Abstruct 

This study assessed possible interactive effects of alcohol and a simulated altitude 

of 12,500 ft. Each of 17 men was trained on the various tasks that comprise the 

Multiple Task Performance Battery and then performed over a 2-week period in four 

experimental sessions, viz, ground level (1,300 ft), with and without alcohol, and 

altitude (12,500 ft), with and without alcohol. Subjects breathed appropriate gas 

mixtures through oxygen masks at both ground level and altitude. Subjects performed 

for 3 hours in the morning, had a 1-hour lunch break, and performed again for 3 

hours in the afternoon. Alcohol doses were 2.2 mL of 100-proof vodka per kilogram 

of body weight mixed with three parts of a selected juice. Each 1-hour test block 

included five 10-minute performance periods with varying workloads and a 10-minute 

period for controlled breathalyzer measurements. Results showed no differential 

effect of simulated altitude on breathalyzer readings (peaks averaged .078% at 

12,500 ft and .077% at ground level). The best performance occurred at ~round level 

under placebo conditions; the 12,500-ft simulated altitude produced some decrement 

for the placebo condition scores. Alcohol at ground level resulted in significantly 

impaired performance during the morning sessions; the addition of altitude to the 

alcohol condition further depressed performance scores, but to about the same extent 

that placebo scores were depressed by altitude. Thus, there was no interactive 

effect of alcohol and altitude on either breathalyzer readings or performance 

scores. However, the general decrement produced by altitude (with or without 

alcohol) serves to reduce further whatever margin of safety remains in performance 

skills following alcohol ingestion. 

17. Key Words 

Alcohol 

Altitude 

Performance 

19. Security Classif. (of this report) 

Unclassified 

Form DOT F 1700.7 (8-72) 

18. Distribution Statement 

Document is available to the public 

through the National Technical Information 

Service, Springfield, Virginia 22161. 

20. Security Classif. (of this page) 21. No. of Pages 22. Price 

8 

Unc lR.co: cd f ied 

Reproduction of completed page authorized 
ACKNOWLEDGMENT 

The assistance of Gordon FUnkhouser, Nelda Milburn, and Linda Van Buskirk in the 

conduct of this study is gratefully acknowledged. 
INTRODUCTION 

SOME EFFECTS OF ALCOOOL AND SIMULATED ALTITUDE ON 

COMPLEX PERFORMANCE SCORES AND BRFATHALYZER RFADINGS 

A previous study (3) from this laboratory assessed performance at a tracking 

task under placebo vs. alcohol conditions at ground level and at 12,000 ft 

simulated in an altitude chamber. Results were complex due to the design of the 

study, which involved a "typical" drinking schedule from evening until midnight. 

Performance tests were conducted prior to drinking (evening), immediately 

following drinking (midnight), and 8 hours after drinking ceased (morning), for 

placebo and alcohol; the midnight session was excluded from a third, sleep 

control condition. Overall, ground vs. altitude scores did not differ 

statistically, but the ingestion of alcohol significantly impaired (midnight) 

performance scores. There was no alcohol/altitude interaction in effects on 

performance, a finding that runs counter to prevalent beliefs. The complexity 

of the findings resides in a performance decrease (compared to ground level) in 

the altitude chamber, only at midnight, under both placebo and alcohol 

conditions. That effect did not occur during any of the three evening and three 

morning sessions. It would seem that fatigue and sleepiness may have interacted 

with the altitude condition at midnight to produce an increased decrement in 

performance scores regardless of whether or not alcohol had been ingested. 

The present study was designed to provide the possibility of replication of the 

ground vs. altitude results noted above without the complexity of fatigue and 

sleepiness introduced by testing after midnighL In addition, the present study 

provided for breathalyzer measures un:ier both ground level and altitude 

conditions; in the previous study such measures were taken at ground level just 

before the chamber ascent. 

ME!' HOD 

Subjects. A total of 17 men between the ages of 21 and 35 years completed the 

experiment. Three other men had difficulty handling the alcohol condition and 

did not complete the study. All men had been selected on the basis on their 

self-reported drinking habits and their stated ability to be able to handle the 

equivalent of four or five drinks in a short period of time. Subjects were 

unaW3.re of the order of presentation of the experimental conditions (alcohol vs. 

placebo; ground vs. altitude) and, in addition, were told that they would be 

receiving "some" alcohol in every drink. 

Altitude. Subjects breathe:i appropriate gas mixtures through oxygen masks to 

simulate both ground level (approximately 1,300 ft) and altitude (approximately 

12,500 ft). The masks were worn both in training and in experimental sessions. 

Alcohol. Subjects drank equal volumes of either a placebo or alcoholic drink at 

the start of each session. Alcohol doses were 2 .2 mL of 1 00-proof vodka per 

kilogram of body weight mixed with three parts of either tomato or orange juice, 

as selected by the subjects. The placebo drink contained a few drops of rum 

extract floated on top of ice cubes primarily to produce the odor of an 

alcoholic beverage. Subjects consumed each drink in a 20-min period. 

1 
Breathalyzer. Breath alcohol levels were assessed by means of an Qnicron 

Intoxilyzer. Practice at using the device was provided the subjects during 

performance training. Subjects learned to take a deep breath, remove the oxygen 

mask, and breathe into the breath-recording device. 

Performance ~asures. Performance um er all conditions was assessed by using 

the Civil Aeromedical Institute ( CAMI) M.lltiple '!ask Performance Battery (MTPB). 

The MTPB measures complex workload performance and time-sharing skills by 

presenting different tasks in various combinations to produce low, moderate, and 

heavy workload conditions. The MTPB apparatus comprises five testing panels 

that contain the displays and response controls for the tasks. Descriptions of 

the seven tasks used in this study are as follows: 

1. Red Warning Lights. This task involved the monitoring of five red lights 

(red lights were normally off). The subject was instructed to push the light 

button whenever a light changed from its normal state. Response times were 

recorded. 

2. Green Warning Lights. This task involved the monitoring of five green 

lights (green lights were normally on). The subject was instructed to push the 

light button whenever a light changed from its normal state. Response times 

were rec ord ed. 

3. ~ters. Four meters, located at the top of the testing panels, were 

monitored for changes in needle indicator position. Normally the indicator 

moved randomly to the left and right with the 100vement centering aroum 11 0." 

Presentation of a signal deflected the continually 100ving indicator to a 

different center point, to either the left or the right of "0," arxl subjects 

were required to push the button on the same side as the direction of 

deflection. Response times were recorded. 

4. ~ntal Arithmetic. 

containing two digits. 

subtract a third number 

keyboard on the testing 

A screen display presented three numbers, each 

The subject had to mentally add the first two numbers, 

from the sum of the first two, and enter the answer on a 

parnl. Accuracy and response time were recorded. 

5. Two-Dimensional Compensatory Tracking. The tracking task was displayed on 

an oscilloscope screen lined with two cross-hairs. A dot of light IOOVe:i arouoo 

the screen driven by a forcing function. The subject was instructed to keep the 

dot in the center of the screen by means of a joystick. Performance was scored 

by using am log circuitry that integra ted absolute error and error squared for 

each dimension. The error-squared measure was converted to vee tor 

root-mean-square ( RMS) error, and vector RMS error xooasures derived from 

horizontal and vertical RMS error scores were used as an index of tracking 

performance. 

6. Problem &llving. This task required the subject to use a trial-and-error 

search procedure to discover the correct sequence in which to press the five 

response buttons in order to solve the problem. Three "feedback" lights 

indicated when any response button was pressed (orange light), when an incorrect 

button was pressed (red light), and when the correct sequence had been entered 

(blue light after completion of sequence). Whenever an incorrect button was 

2 
pushoo, the subject was required to reenter the correct portion of the sequence 

already discovered before the search could continue. Twenty seconds after the 

solution of a problem, subjects were required to reenter the solution 

(confirmation phase). Speed of the oolution phase, speed of the confirmation 

phase, proportion of redundant responses made during the oolution phase, and 

proportion of error responses in the confirmation phase were the measures 

comprising the scores on the problem-solving task. 

7. Pattern Discrimination. A screen display presented three six-column 

bargraphs sequentially. Problems were of a "matching to sample" form. The 

first "sample" pattern was followed by two comparison patterns. The subject 

respondoo by pressing one of three appropriately markoo buttons to indicate that 

either one, two, or neither of the comparison patterns matched the sample. The 

sample pattern appeared for 5 seconds, and each comparison pattern appeared for 

3 seconds, with 2 seconds between successive patterns. Accuracy and response 

time were recorded. 

Each of five training sessions comprised three 50-minute periods, with a 

10-minute break after each period. Each 50-minute period contained five 

10-minu te intervals of low, moderate, and heavy ~rkloads. Red and green 

warning lights and meters (both monitoring tasks) were presented in all five 

~rkload intervals. The five successive intervals involvoo the following array 

of tasks: first (low workload), tracking in addition to monitoring; second 

(moderate workload), monitoring, mental arithmetic, and problem solving; third 

(moderate ~rkload), monitoring, tracking, and problem solving; fourth 

(high-moderate workload), monitoring, pattern dscrimina tion, and problem 

solving; and fifth (high ~rkload), monitoring, pattern discrimination, · mental 

arithmetic, and tracking. 

Procooure. Following 12 1/2 hours of training on the MTPB, each subject 

performed in four separate experimenta;l sessions spread over a 2-week period. 

The four sessions were groun::i level ( 1 ,300 ft), with and without alcohol, and 

altitude (12,500 ft), with and withwt alcohol. 

The order of presentation of the condition combinations was approximately 

counterbalancoo. Subjects performed in groups of two or more for 3 hours in the 

morning, had a 1-hour lunch break, and performed again for 3 hours in the 

afternoon. Each 3-hour test block included three 60-minute cycles; within each 

cycle there were five 10-minute performan::!e periods, with ~rkload varying from 

light to heavy, followed by a 10-minute period for controlled breathalyzer 

measurements. The first test block began 1/2 hour after the placebo or the 

alcohol was ingested. Twenty minutes after ingestion of alcohol or placebo, at 

the start of the lunch break, and at the conclusion of testing, subjects 

completed nine-point rating forms assessing their degrees of attentiveness, 

tired oo ss, tenseness, bored om, and irritability (e. g. , from 1 "very inattentive" 

through 9 "very attentive"). 

RESULTS 

!Tea thalyzer. Maan breathalyzer levels were virtually identical for the groun::i 

level and the simulated altitude conditions at every period of measurement (see 

Figure 1 ). Peak values were 78 mg% during the altitude condition and 77 mg% 

3 
.p. 

80 

f- 60 z CONDITIONS w 

u .. 12.S(J0ft. 

0::: X GROUI'«l __ w 

a... 

(/) 

::::E 

40 

<{ 

::J 

_J 

20 

0 

-100 0 100 200 300 400 500 

TIME (MINUTES) 

Figure 1. Breathalyzer readings recorded 

from 17 men at ground level and 

at a simulat ed altitude of 12,500 

feet prior to and f ollowing the 

ingestion of 2.2 mL of 100-proof 

vodka per kg of body weight. 

540 

520 

w 111 -.... ....... '!B······

0:::: 

0 

u ......0- 

(/) 500 CY.--- 

z 

<{ w 

::::E 

480 '\ I 

'\I 

460 " 

0 1 2 

Fi gure 2. Mean composi

MTPB tasks fo

without alcoh

and at simula

6 work periodfollowed the 
during the groun:l level condition. The simulated altitude of 12,500 ft had no 

effect on the brea thalyzer readings. 

MTPB Performance. The overall composite scores for the seven MTPB tasks were 

calculated for each ~rk hour and condition (see Figure 2 ). The best 

performance occurred at groun:l level un:ler placebo conditions; the 12,500-ft 

simulatoo altitude produced some decrement for the placebo condition scores. 

Alcohol at groun:l level resulted in significantly impaired performame during 

the first 3 hours after drinking; the addition of altitude to the alcohol 

condition further depressed performame scores, but to about the same extent 

that placebo scores were depressed by altitude. 

Statistically, an amlysis of variance indicated significantly ( p < .01) poorer 

performance as a result of ingesting alcohol, being at altitude, an:l performing 

earlier in the day. Only one interaction a100ng these main effects was 

statistically significant, viz, alcohol aixi work period ( p < • 0 1 ). That 

interaction accounts for the overall poorer performance of subjects earlier in 

the day; as can be derived from Figure 2, the alcd'lol conditions had strong 

depressing effects on performame scores during the first 3 hours of testing. 

Thus, there was no interactive effect of alcohol and altitude on performame 

scores. There were also no differential effects of the two major conditions 

(alcohol and altitude) on the five low-to-high ~rkload levels (i.e., the five 

levels of workload were equally affected by the major conditions). 

The individual tasks showed similar results (Table 1 ). The main effects of 

alcohol and altitude were significant for five of the seven tasks (the 

exceptions were: for alcd'lol, arithmetic and problem solving; for altitude, 

red lights and tracking). For all tasks, there were significant effects for 

workload (higher ~rkloads generally lowered performame scores) and for work 

periods (the afternoon periods tended to show better performame than the 

lOOming ~rk periods). Related to the latter finding was a significant ~rk 

period by alcohol interaction that was present for all tasks except arithmetic 

and problem solving (for which no nain effect of alcohol was obtained). Two 

individual tasks each showed an alcd'lol by altitude interaction (target 

identification and problem solving), but that interaction was in the direction 

opposite \oilat ~uld be expected (see Th.ble 1); i.e. , performame un:l er alcd'lol 

conditions was affected slightly less by altitude than was performame un:ler 

placebo conditions. 

MJod R3.tings. · Average ratings for attentiveness, tiredness, tenseness, boredom, 

and irritation are presented in Th.ble 2. In alcohol vs. placebo comparisons, 

analysis of variance indicated that alcd'lol significantly reduced tenseness and 

increased irritation (p < .05 in both cases). The altitude coodition 

significantly increased feelings of boredom an:l decreased irritation as compared 

with the groun:l level condition ( p < .05 in both cases). Time-of-day 

comparisons were statistically significant for all five 100od factors; i.e. , 

tired~ ss, tenseness, boredom, and irritation increased regularly from morning 

through midday to the late afternoon measurement time ( p < .01 in all cases). 

Attentiveness was highest in the 100ming (p < .05), was lo~st at midday, and 

showed roodest recovery in the afternoon. Variations in the 100od scores were 

u nre la too to performance. 

5 
TABLE I. Standard Scores (Means and standard Deviations) and Statistical 

()Jtcomes for Individual MTPB Tasks as a function of Hourly Work 

Periods, Workload, Alcohol, and Simulated Altitude (12,500 ft). 

STANDARD SCORES STATISTICAL SIGNIFICANCE i.£ <.05) 

Alcohol Placebo Main Effects Interactions 

Per- Work Ale/ Ale/ Ale/ Alt/ Alt/ Wkl/ 

----

Alt Grd Alt Grd Ale Alt iod Load Alt Per Wkl Per Wkl Per - - - - -

Green M 487 4Yb 500 515 .o 1 .01 .05 .o 1 .01 

Lights SD 104 100 102 By 

Red t-1 482 497 510 511 .o 1 .05 .01 .05 

Lights SD 116 95 96 t37 

~leters M 490 49ti ')00 511 .01 .01 .01 .01 .o 1 

SD 9b 105 103 92 

Tr·acking M 4':1 1 492 509 ')08 .o 1 .o 1 .o 1 .01 .01 

SD 9 3 98 98 92 

Arith- H 49 5 49 7 49 5 513 .05 .o 1 .01 .o 1 .01 

me tic SD 84 78 89 70 

Target M lltl 3 4811 49 4 53ti .o 1 .01 .0 I .o 1 .o 1 .o 1 .05 

Ident. SD n ':11 9:l 64 

Problem M 4':1 3 501 491 514 .o 1 . 01 .01 .05 

Solving SD 8') 72 72 b5 

TABLE II. Means and Standard Deviations for Ratings of Mood Factors by Drug, 

Altitude, and Time. 

TIME OF 

DRUG ALTITUDE MEASUREMENT 

Ground Before After 

Factors Alcohol Placebo 12z500 Level Test Noon Test 

Attentiveness M 4.78 4.99 4.82 4.95 5.26 4.62 4. 78* 

SD 1.68 1.47 1.64 1.53 1.59 1.59 1. 50 

Tiredness M 5.53 5.62 5.56 5.59 5 .o 1 5.79 5.91** 

SD 1.64 1 .62 1.65 1.60 1.49 1.60 1.64 

Tenseness M 4.10 4.49* 4.34 4.25 3.79 4.21 4.88•• 

SD 1 .81 1.68 1. 74 1. 78 1.66 1.69 1. 76 

Boredom M 4. 73 4.82 4.56 4.99* 4.13 5.00 5.19** 

SD 2.22 1.95 1.96 2. 19 1. 79 2. 16 2. 15 

Irritation M 2.97 2.51* 2.51 2.97* 2.06 2.82 3.34** 

SD 2.1 0 1. 81 1.88 2.05 1. 68 1.90 2. 11 

• p < .05 •• p < • 01 

6 
DISCUSSION 

In this study, the ingestion of alcdlol resulted in a significant impairment in 

complex performme tasks for the first 3-4 hours after the drinking period. As 

a separate effect, the simulated altitude of 12,500 ft produced a smaller, but 

statistically significant, decrement in performame scores urn er both placebo 

and alcohol conditions. Thus, performance was adversely affected both by 

altitude and by alcdlol, but there W3.S no synergistic interaction between the 

two. M:>reover, the breathalyzer recordings showed no differences between grourn 

and simulated altitude conditions. 

There exists ample evidence that acute alcdlol intoxication impairs abilities 

related to flying (1,2,4,5). Further, based on several older studies (9,10,11), 

t-bFarlan:i (8) concluded that "the alcdlol in two or three cocktails would have 

the physiological action of four or five drinks at altitude of approximately 

10,000 to 12,000 ft." That cooclusion was rooted in the notion that the "oxygen 

W3.nt" consequent to exposure to higher altitudes would combine with 

alcohol-induced impairment of tissue cells in using oxygen properly and produce 

higher and more rapidly achieved peak blood alcdlol levels (BAL's) as well as 

performme impairment. 

The present study and three previous studies (3,6,7) suggest that alcdlol 

effects at altitudes of 12,500 ft or less are not so simply defined. Neither 

this study (using oxygen masks and a brea thalyzer) nor two previous 

investigations (both conducted in an altitude chamber and using blood samples) 

have demonstrated any difference in BAL 's between grourn level am 12,000- to 

12,500-ft conditions (6,7). Further, this study am its antecedent (3) showed 

no interactive effects on performame of alcdlol and altitude. Alcdlol clearly 

produced decrements in performame. However, altitude also had a negative 

influence on performme (with or without alcdlol) in this study (12,500 ft ) am 

showed a similar effect in a previous study (12,000 ft) only during a midnight 

session when subjects were sleepy. 

The data across these several studies suggest t!'lat (i) SAL's of .100% or less 

are not differently affected at altitudes of 12,000-12,500 ft when compared with 

groum level; (ii) there is no syrergistic interaction on performame between 

those altitudes and those BAL's, although performame is adversely affected by 

alcohol at groun::i level and at altitude; (iii) altitudes of 12,000-12,500 ft 

may, of themselves, produce performame decrements in oome subjects or un~er 

oome conditions; (iv) when the latter occurs, the deleterious effect of alcdlol 

appears to be simply additive. 

7 
REFERENCES 

1. Aksnes ED. Effect of small dosages of alcc:hol upon performame in a link 

trainer. J. Aviation ~d. 1954;25:680-88 and 693. 

2. Billings CE, Wick RL, Gerke RJ, Olase RC. Effects of ethyl alcohol on pilot 

performal'K!e. Aerospace ~d. 1973;44(4):379-82. 

3. Collins WE. Performame effects of alcc:hol intoxication an:t hangover at groun:t 

level and at simulate:1 altitude. Aviat. Space Ehviron. ~d. 

1980; 5(4) :327-51. 

4. Henry PH, Flueck JA, Sanford JF, Keiser HN, M:!Nee RC, Walter WH III, Webster KH, 

Hartman BO, Lamaster MC. Assessment of performame in a link GAT-1 flight 

simulator at three alcohol dose levels. Aerospace ~d. 1974;45(1 ):33-44. 

5. Henry PH, .Davis 'IQ, Engelken &J, Triebwasser JH, Lamaster MC. Alcc:hol-induce:l 

performame decrements assessed by two link trainer tasks using experienced 

pilots. Aerospace ~d. 19 74; 45 ( 10): 1180-89. 

6. Higgins EA, .Davis AW, Vaughn JA, Funkhruser GE, G:l.lerston EM. The effects of 

alcohol at three simulate:l aircraft cabin cooditions. Washington, DC, 1968; 

FAA Office of Aviation ~d icine ~port, F AA-AM-68-18. 

7. Higgins EA, Vaughan JA, F'unkhruser GE. Blood alcc:hol concentrations as affected 

by combinations of alcoholic beverage dosages and altitude. Washington, DC, 

1970; FAA Office of Aviation ~dicine ~port, FAA-AM-70-5. 

8. M:!Farlan:i RA. Human Factors in Air 'Iransportation. 1953. New York: 

M:!Graw-Hill. 

9. M:! Farland RA, Barach AL. The relationship between alcc:hol intoxication and 

anoxemia. American J. ~d. Science 1936; 192(2):186-98. 

10. M:!Farland RA, Forbes WH. The metabolism of alcc:hol in man at high altitudes. 

Human Biology 1936;8(3):387-98. 

11. Newmn HW. The effects of altitude on alcc:hol tolerame. Quarterly J. of 

Studies oo Alcohol 1949; 10:398-403. 

8