Garnet A. McLean

Cynthia L. Corbett

Civil Aerospace Medical Institute

Federal Aviation Administration

Oklahoma City, OK 73125

January 2004

Final Report

This document is available to the public

through the National Technical Information

Service, Springfield, Virginia 22161.

Office of Aerospace Medicine

Washington, DC 20591

DOT/FAA/AM-04/2 Access-To-Egress III: Repeated 

Measurement of Factors That 

Control the Emergency Evacuation 

of Passengers Through the Transport 

Airplane Type-III Overwing Exit 
NOTICE

This document is disseminated under the sponsorship of

the U.S. Department of Transportation in the interest of

information exchange. The United States Government

assumes no liability for the contents thereof.
i

Technical Report Documentation Page 

1. Report No. 

DOT/FAA/AM-04/2

2. Government Accession No. 3. Recipient's Catalog No. 

4. Title And Subtitle

Access-To-Egress III: Repeated Measurement of Factors That Control the 

Emergency Evacuation of Passengers Through the Transport Airplane Type-III 

Overwing Exit 

5. Report Date

January 2004 

7. Author(s) 

McLean GA, Corbett CL 

9. Performing Organization Name and Address 

FAA Civil Aerospace Medical Institute 

P.O. Box 25082` 

Oklahoma City, OK 73125

8. Performing Organization Rep

12. Sponsoring Agency Name and Address 10. Work Unit No. (TRAIS) 

Office of Aerospace Medicine 

Federal Aviation Administration 

800 Independence Ave. 

Washington, DC 20591 

11. Contract or Grant No. 

15. Supplemental Notes 13. Type of Report and Period 

This work was performed under task AM-B-01-PRS-93. 

14. Sponsoring Agency Code 

16. Abstract 

Simulated emergency evacuations were conducted from a narrow-body transport airplane simulator 

through a Type-III overwing exit. The independent variables were passageway configuration, hatch disposal 

location, subject group size (density), and subject motivation level. Additional variables of interest included 

individual subject characteristics, i.e., gender, age, waist size, and height, shown in previous studies to 

significantly affect emergency egress. Subjects were restricted to those who had no previous emergency 

evacuation (research) history. 

Evacuation trials were conducted with 48 groups of either 30, 50, or 70 subjects per group, totaling 2,544 

subject participants. Each subject group completed 4 evacuation trials, totaling 192 group evacuations, 

which included 10,176 individual subject exit crossings. The dependent variable of interest was individual 

subject egress time. 

Small but significant independent variable main effects on mean individual egress times were found for 

passageway configuration (p<.001), subject group motivation (p<.001), and subject group density (p<.05); 

significance of these effects was potentiated by the extremely large number of subject observations. The 

effects of subject waist size (p<.0001), gender (p<.0001), and age (p<.0001) on mean individual egress 

times were much more robust. The within-subjects main effect of evacuation trial (experience) failed to 

achieve significance (p<.63), although within-subjects effects were found for group motivation level 

(p<.0004), the combination of group motivation level and hatch disposal location (p=.03), and the 

combination of passageway configuration and hatch disposal location (p<.007), via their interactions with 

individual egress trial. 

The findings replicate prior research showing that the physical attributes of subjects produce large 

differences in emergency evacuation performance, whereas airplane configuration has minimal effects on 

emergency egress, as long as ergonomic minimums are respected. Where such problems do exist, evacuation 

experience acts to mitigate such negative effects, as does proper passenger management by flight attendants.

17. Key Words 

Aircraft Evacuation, Passageway Configuration, Hatch 

Operation, Competitive Egress, Individual Subject 

Characteristics, Passenger Management 

18. Distribution Statement 

Document is available to the public through the 

National Technical Information Service, 

Springfield, VA 22161 

19. Security Classif. (of this report) 

Unclassified 

20. Security Classif. (of this page)

Unclassified 

21. No. of Pages 

24

22. Price 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized 

iii

ACKNOWLEDGMENTS

 The authors heartily acknowledge the untiring efforts of those who gave so generously of their 

time and energy toward the success of this project. The dedication each of them displayed is a tribute to 

the professionalism embodied in the personnel of the Civil Aerospace Medical Institute and their willingness to assist almost any time or day. Among all those who contributed, special thanks go to our research 

support staff:

Tracie Allison Joe Beasley Rick Butler Patricia Calvert

Kristi Craft Chuck DeJohn David DeSelms Rick DeWeese

Dave Dyer Jerrod Epple Wilma Fairman Van Gowdy

Ken Larcher Rusty Lewis Edward Matheke Jerry McDown 

Ronnie Minnick Becky Orman David Palmerton Keith Porter

Donna Potter Bryan Provine Lori Samuel Robert Shaffstall 

Steve Veronneau James Whinnery Greg Winters Alex Wolbrink 

Kathi Wood

 The project could also not have been accomplished without several contract personnel, who recruited and managed our subjects, helped out with conducting the evacuation trials, and maintained the 

evacuation simulator, which was under constant threat of demolition by the onslaught of zealous evacuees. 

Those in our debt include: 

Jason Garvin Suanne Hanson Linda Hoover John Howard 

Julianne Jacks Jerry Johnson Jim King Lorri King

Robert McCawley Heather Munn Dave Ruppel Stephanie Sanders

Buck Walker Vicky Wilson

 We also wish to thank the fine paramedics from EMSA, who helped us those few times when 

things went awry. Thank you all for a project well done.

1

REPEATED MEASUREMENT OF FACTORS THAT CONTROL

THE EMERGENCY EVACUATION OF PASSENGERS THROUGH

THE TRANSPORT AIRPLANE TYPE-III OVERWING EXIT

INTRODUCTION

Over the last 15 years, a research program of international scope has been dedicated to examining emergency 

evacuations through the transport airplane Type-III 

overwing emergency exit. The genesis of this activity 

was the 1985 crash of the British Airtours Boeing 737 

airplane at Manchester, England, in which a number 

of passengers died in an apparent attempt to approach 

and egress through the Type-III overwing exit (AAIB 

Report 8/88). A second accident involved a B-737 and 

a Fairchild Metroliner at Los Angeles International airport in 1991 (NTSB/AAR-91/08), in which more deaths 

were associated with attempts to use the Type-III exit. 

Restrictive cabin interior configurations limiting access 

to, and increasing evacuation times through, the TypeIII exits were judged to be a likely cause of the deaths. 

Since that time, many studies of evacuation through the 

Type-III exit have been conducted to examine the role 

of airplane configuration and operation at the Type-III 

exit; this current study is the latest and most exhaustive 

attempt to identify cabin configurations and operations 

that promote efficient egress. This report is the third in 

a series of reports of this study designed to catalog the 

relevant factors that control evacuation through the TypeIII exit. The initial report, Access-to-Egress I: Interactive effects of factors that control emergency evacuation 

through the transport airplane Type-III overwing exit, 

(McLean, Corbett, Larcher, McDown, Palmerton, Porter, 

Shaffstall, & Odom, 2002), provides the findings of the 

study with regard to the first evacuation trial for each 

subject group in which subjects were completely naïve 

regarding emergency evacuation. The second report in 

the series, Access-to-Egress II: Subject management and 

injuries in a study of emergency evacuation through the 

Type-III exit, (Corbett, McLean, & Whinnery, 2003), 

examined subject processing and health effects of airplane 

evacuations on subjects. This current report provides the 

residual evacuation-related results of the study, i.e., the 

effects on evacuation efficiency of additional evacuation 

trials for each group, as subjects became progressively 

more experienced in emergency egress. 

METHODS

Research Design. The study employed a 4-way 

(Passageway Configuration x Hatch Disposal Location 

x Subject Group Motivation Level x Subject Group Density) factorial design. Motivation level was nested within 

subject group density, which was distributed uniformly 

across passageway configuration nested within hatch 

disposal location (see Table 1). Subjects were screened 

out for prior experience in evacuation research; after the 

fact it was discovered that one of the subjects had been 

in an actual emergency airplane evacuation. 

In addition to passageway configuration, the other 

independent variables in the design were selected for their 

known effects on egress performance, as well as their 

potential for interactions with passageway configuration, 

that could address the issue of access to egress. Hatch 

disposal location was chosen because of the potential 

for a mislaid hatch to negatively influence access to the 

exit; subject motivation level was included because of the 

demonstrated ability of financial incentives to produce 

extreme subject behaviors (e.g., Muir, Bottomley, & Hall, 

1992) that can impede egress; and subject group density 

(size) was included because a prior research study had 

shown nonlinear increases in evacuation time, as the 

number of subjects per group was increased (McLean, 

Corbett, & George, 1999). 

Participants. A total of 2,400 subjects was apportioned 

among the 48 experimental groups, one-third of which 

contained either 30, 50, or 70 subjects. An additional 144 

subjects were added to the subject pool as hatch operators (one for each evacuation trial), resulting in a total of 

2,544 human subjects being employed. The subject pool 

was comprised of 51% males and 49% females; subjects 

ranged in age from 18 to 65 years of age, in weight from 

95 to 416 pounds, and in height from 54 to 81 inches. 

Motivation. The low motivation condition, often 

termed cooperative egress, was established by a briefing 

given prior to each trial. Subjects in all groups were told 

that the airplane had crashed and was on fire, and that to 

stay alive they had to hurry to get out. This was the only 

instruction for half the groups. In the high motivation 
2 

condition, competitive egress, double pay was offered to 

subjects who were among the first 25% of their group 

to evacuate the airplane simulator, averaged across all 4 

evacuation trials. The technique of averaging across trials was intended to assure sustained competition among 

all subjects in any individual trial; seat assignment was 

rotated on evacuation trials to give all subjects equal opportunity to earn the bonus.

Apparatus. The airplane simulator was configured with 

six-abreast seating (e.g., B-737) and equipped with a single 

Type-III overwing exit located on the right side of the 

cabin 40% of the total distance aft of the front door. The 

exit opening was 20” wide and 38” high, with a step-up 

distance of 18” inside the simulator and a step-down of 

27” from the centerline of the exit to a sloped winglet

outside the simulator. The weight of the hatch was set 

at 45 pounds for all trials. 

Passageway Configuration. Four different passageway configurations leading from the main aisle to 

the exit were used in the study; three of these included 

single passageways between triple seat assemblies and the 

fourth employed 2 passageways, one fore and one aft 

of a seat assembly in which the outboard seat had been 

removed. The single passageways employed 10”, 13”, and 

20” passageway widths, with 14”, 10”, and 5” aft seat 

encroachment distances, respectively; the dual passageway 

configuration with the outboard seat removed had the 

seat assembly placed directly adjacent to the Type-III exit. 

Figures 1 through 4 depict the passageway configurations 

employed. The tray tables in the passageway seats were 

stowed in the rigid armrests; all seat backs throughout 

the cabin were locked to prevent breakover. Remaining 

seat pitch was set at 31 inches.

Hatch Disposal Location. At the start of each evacuation trial, the Type-III exit hatch was removed from its 

typical location in the side of the fuselage by the hatch 

operator, who placed it either inside or outside the simulator, depending on the specific experimental condition. 

The hatch was placed on the exit row seat assembly for 

inside hatch disposal (e.g., Figure 5); outside hatch disposal was achieved by having the hatch operator throw 

it through the exit opening onto the winglet (e.g., Figure 

6), where a research confederate would pull it out of the 

way to minimize the possibility of subject injury during 

the ensuing evacuation. In both cases the hatch operator 

would then climb through the exit, either leading the 

evacuation or not, depending on whether another subject 

had squeezed through first. 

Hatch Operators. Hatch operators were selected randomly as they entered the lab and were sequestered, away 

from their evacuation group, where they were briefed about 

hatch operation by being shown graphics taken from a 

typical airline safety briefing card (see Figure 7). No verbal 

instruction was given to them about the procedure or the 

evacuation trial for which they would be opening the exit, 

except to inform them that a buzzer would be used to 

start the evacuation. Immediately before the evacuation 

trial in which each hatch operator participated, s/he was 

escorted to the simulator and seated immediately adjacent 

to the Type-III exit. After each of the first three trials for 

Table 1 

Research Design with Mean Total Group Evacuation Times*

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3

Figure 1 

20” Passageway With 5” Encroachment 

Figure 2 

13” Passageway With 10” Encroachment 

 

5” 

20” 

10” 

13” 

EXIT 

EXIT 
4 

Figure 3 

10” Passageway With 14” Encroachment 

Figure 4 

Dual 6” Passageways With Outboard Seat Removed 

14” 

10” 

6” 6” 

EXIT 

EXIT 
5

Figure 5

Typical Inside Hatch disposal Location

Figure 6

Typical Outside Hatch disposal LocationFigure 5
6 

each group, the hatch operator was relocated to another 

area to preclude the possibility of information sharing 

with subsequent hatch operators. 

Flight Attendant Participation. Two flight attendants, 

one located in the front of the cabin and one in the rear, 

were seated in jumpseats at the start of each trial. At the 

sound of the start buzzer, the forward flight attendant 

pointed at the exit and commanded the hatch operator 

to “Open That Hatch.” Both flight attendants immediately started commanding “Unbuckle Your Seatbelts... 

Evacuate... Get Out... Get Out... Hurry,” as they 

started herding the subjects toward the Type-III exit. The 

flight attendants continued to command the evacuation 

throughout each entire trial, but they were not allowed 

to physically assist subjects in any way. Their purpose 

was to keep subjects on task as would be expected in an 

actual emergency evacuation.

Procedure. Prospective subjects were in-processed according to IRB requirements, and then they completed 

questionnaires about their personal demographics and 

their attention to, and knowledge about, actual preflight 

briefings on airliners. Their physical attributes (height, 

weight, etc.) were then measured, and they were photographed for identification purposes before being escorted 

to the simulator. After a familiarization briefing, they 

were given a boarding card with the first seat assignment. 

They entered the simulator and seated themselves accordingly. Following any subject questions, the preflight

briefing was read, the flight attendants assumed their 

assigned places, and the start buzzer was sounded after a 

variable interval of 5 to 30 seconds. The flight attendants 

began shouting and gesturing for subjects to unbuckle 

their seatbelts and proceed through the exit. The hatch 

operator, seated next to the exit, removed the hatch and 

disposed of it, allowing the evacuation flow to begin. 

After the trial was over, subjects were regrouped outside 

the simulator for the next trial. 

Data Archival, Reduction, and Analysis. Eight video 

cameras, 4 inside the simulator and 4 outside, recorded 

all experimental trials (see Figure 8). Videotapes of each 

trial were examined manually to obtain group and individual evacuation times; the data were analyzed using the 

multiple regression, analysis-of-variance, and analysis-ofcovariance routines in SPSS®

 10.0 (1999). 

Each subject group completed four evacuation trials. 

Total group evacuation time for each trial was defined as 

beginning at the time the start buzzer sounded and lasting until the last subject had traversed the Type-III exit 

opening (see cells in Table 1). Because of the differences 

in the number of subjects within the groups, no statistical 

analyses were conducted on these group times. Instead, 

the times were divided into hatch removal/disposal and 

individual subject egress times. Hatch removal and disposal time lasted from the initial sounding of the start 

Figure 7

Hatch Operator Briefing Cards

Outside Hatch Disposal

Inside Hatch Disposal
7

buzzer until the first evacuee began to emerge from the 

exit opening. Individual subject egress time was defined 

as the period lasting from the time (videotape frame) one 

subject had completely passed through the exit opening 

until the time the next subject was completely through 

the opening. 

The results related to operation of the hatch and 

preparation of the exit for evacuation were reported in 

McLean et al. (2002), as were the first trial (between-subjects) effects on individual egress time of the independent 

variables and the individual subject attributes. The mean 

and repeated-measures independent and human subject 

variable effects on individual subject egress times across 

all 4 evacuation trials are reported here. 

RESULTS

The large number of individual egress time observations provided an enormous amount of statistical power, 

allowing the data to be screened for significant egress time 

outliers, i.e., those times greater than 3 standard deviations 

above the mean for each passageway configuration. This 

resulted in the removal of 131 of the 10,176 individual 

subject egress times; outlying times ranged from 3.77 to 

Figure 8

Data Acquisition and Archival System

18.63 seconds. These times resulted from errant individual 

subject behavior, the exit being jammed with subjects, or 

the hatch becoming an impediment. However, no evacuation trial was halted because of exit blockade. 

Note that, in the figures presented below, solid lines are 

used to connect interval data points within any category, 

whereas dotted lines are used to connect data points for 

discrete classes of a variable. For example, the 10”, 13”, 

and 20” passageway data points are connected via solid 

lines, and then the dual 6” passageway data points are 

connected to the single 10” passageway data points via 

a dotted line. This particular distinction was made to 

highlight the fact that it was the additional passageway 

available for egress with the most restrictive (6”) passageway configuration that afforded individual egress 

times generally comparable to those produced by the 

less restrictive of the single passageway configurations. 

All variables, including both design factors and subject 

attributes, were subjected to an initial multiple regression 

analysis to assess relative significance with regard to mean 

individual subject egress time. In a manner identical to 

the effects on egress found for subjects in their first evacuation trial, waist size accounted for the largest amount 

of variance in the data (p<.0001), followed by gender 
8 

(p<.0001) and age (p<.0001). Neither subject height, 

nor any of the independent variables added further to 

the regression model. 

These same variables had been found in the study of 

the first (naïve subject) trial to account for the largest 

amount of variance in the data; thus, the cumulative 

effects of individual subject egress experience did not 

alter the relative importance of personal characteristics 

in controlling egress performance. This equivalence of 

effects provided the rationale for an identical set of analyses 

on the data from all evacuation trials. First, individual 

subject characteristics were categorized to provide interval 

data that would allow better visualization of the subject 

attribute effects. Five subcategories of age, waist size, and 

height, distributed to achieve a similar number of subjects per sub-category, were created in addition to gender. 

These variables were subjected to a univariate analysis of 

variance (ANOVA) of mean individual egress times across 

all trials. Significant main effects were replicated for waist 

size (p<.001; Figure 9) gender (p<.001; Figure 10), and 

age (p<.001; Figure 11). Subject height also unexpectedly 

achieved statistical significance (p<.02; Figure 12).

Mean Effects of the Independent Variables. A univariate analysis of variance (ANOVA) was used to assess 

the within-subjects effects of the independent variables 

on mean individual egress time across all trials. There 

were small but significant main effects of passageway configuration (p<.001; Figure 13), subject group motivation 

(p<.001; Figure 14), and subject group density (p<.05; 

Figure 15), but the hatch disposal location main effect 

failed to achieve significance (p<.11; Figure 16). Significant interaction effects were also found for passageway 

configuration by hatch disposal location (p<.02; Figure 17) 

and passageway configuration by hatch disposal location 

by subject group motivation level (p<.04; Figure 18). The 

significance of the main effects resulted primarily from the 

extremely large degree of statistical power. Importantly, 

the general character of these main effects was unchanged 

from the results obtained on only the first trial of the study 

(see McLean et al., 2002). The passageway configuration by hatch disposal location interaction effect was also 

much like the first-trial interaction effect, although the 

differences in individual egress time for the hatch disposal locations at the 6” passageway configuration on the 

first trial were eliminated in subsequent trials to reduce 

the significance of the interaction effect. The remaining 

significance of that 2-way interaction was shown in the 

passageway configuration by hatch disposal location by 

subject group motivation interaction effect to result from 

significant differences in individual egress time in the 13” 

passageway configuration. Figure 18 shows the increase 

in individual egress time in the 13” configuration when 

the hatch was placed inside the airplane simulator; this 

increase in egress time was produced by the hatch being 

dislodged from its resting place on the seat assembly in 

some of the trials to become an impediment to those 

evacuations. In sum, these effects generally mirrored 

those in the first (naïve-subjects) trial. 

A (2-way) passageway configuration by subject waist 

size interaction effect (p=.005; Figure 19) was found, as 

was a 3-way interaction effect for the combination of 

passageway configuration, subject waist size, and gender 

(p=.002; Figure 20). A 3-way interaction effect was also 

found for the combination of passageway configuration, 

subject age, and subject gender (p<.0004; Figure 21). The 

character of all these effects was very reminiscent of the 

first trial effects, owing to the generally increased individual egress times for wider, older subjects, particularly 

women. These effects became more pronounced as the 

passageway configuration became more restrictive. 

The relative magnitude of effects, including both 

the independent variable and subject attribute effects, 

can be seen in Figure 22, which displays the large influence that the subject attributes had on the evacuations. 

Except for a couple of minor position shifts within this 

magnitude of effects hierarchy, the relative effect of each 

variable on individual egress time was maintained from 

the first through the last trial, suggesting that the general 

character of the evacuations did not change as subjects 

became more experienced.

Repeated Measurement of the Independent Variable Effects. A repeated-measures analysis of covariance 

(ANCOVA), using the three regression model (human 

subject) factors as covariates, was used to assess the withinsubjects effects of the independent variables on a trial-bytrial basis. The expected main effect of evacuation trial 

failed to achieve statistical significance (p<.63; Figure 

23), despite a small improvement in egress time with 

increasing evacuation experience. However, significant 

differences in the effects of certain of the independent 

variables were shown across trials via interactions of evacuation trial with subject group motivation level (p<.0004; 

Figure 24), the combination of subject group motivation 

level and hatch disposal location (p=.03; Figure 25), and 

the combination of passageway configuration and hatch 

disposal location (p<.007; Figure 26). The (2-way) egress 

trial by subject group motivation level interaction effect 

resulted from the typical monotonic decline in individual 

egress time known to occur with cumulative experience 

in low-motivation conditions, coupled with a flatter, 

but generally faster, set of times in the high-motivation 

condition. This situation caused the respective curves to 

cross by the last trial, where the high-motivation subjects 

were slower than their low-motivation counterparts. The 

(3-way) evacuation trial by subject group motivation level 

by hatch disposal location interaction generally mirrored 
9

Figure 9 

Average Individual Subject Egress Time 

Subject Waist Size Main Effect

1.88

1.65

1.44

1.28 1.37

0.0

0.5

1.0

1.5

2.0

2.5

23-31 32-34 35-38 39-41 41-62

Waist Size in Inches

Mean Egress Time in Seconds

p<.001

Figure 10 

Average Individual Subject Egress Time 

Subject Gender Main Effect

1.58

1.46

0.0

0.5

1.0

1.5

2.0

2.5

Male Female

Subject Gender

Mean Egress Time in Seconds

p<.001
10 

Figure 11 

Average Individual Subject Egress Time 

Subject Age Main Effect

1.91

1.64

1.48

1.40

1.29

0.0

0.5

1.0

1.5

2.0

2.5

18-22 23-32 33-42 43-52 53-65

Age in Years

Mean Egress Time in Seconds

p<.001

Figure 12 

Average Individual Subject Egress Time 

Subject Height Main Effect

1.53

1.50

1.47

1.51

1.59

0.0

0.5

1.0

1.5

2.0

2.5

57-64 65-66 67-68 69-71 72-79

Subject Height in Inches

Mean Time in Seconds

p<.02
11

Figure 13 

Average Individual Subject Egress Time 

Passageway Configuration Main Effect

1.41

1.54

1.61

1.52

0.0

0.5

1.0

1.5

2.0

2.5

6" 10" 13" 20"

Passageway Configuration

Mean Time in Seconds

p < .001

Figure 14 

Average Individual Subject Egress Time 

Subject Group MotivationMain Effect

1.51 1.53

0.0

0.5

1.0

1.5

2.0

2.5

Low High

Group Motivation

Mean Time in Seconds

p < .001
12 

Figure 15 

Average Individual Subject Egress Time 

Subject Group Density Main Effect

1.54 1.48 1.51

0.0

0.5

1.0

1.5

2.0

2.5

Low (30) Medium (50) High (70)

Group Density

Mean Time in Seconds

p < .05

Figure 16 

Average Individual Subject Egress Time 

Hatch Disposal Location Main Effect

1.54 1.50

0.0

0.5

1.0

1.5

2.0

2.5

In Out

Hatch Disposal Location

Mean Time in Seconds

p < .11
13

Figure 17 

Average Individual Subject Egress Time 

Passageway Configuration X Hatch Disposal Location Interaction

1.52

1.60

1.59

1.43

1.51

1.61

1.49 1.39

0.0

0.5

1.0

1.5

2.0

2.5

6" 10" 13" 20" Passageway Configuration

Mean Time in Seconds

In Out

p < .02

Hatch Disposal Location:

Figure 18 

Average Individual Subject Egress Time 

Passageway Configuration X Hatch Disposal Location X 

Subject Group Motivation Interaction

1.36

1.44

1.59 1.64

1.53

1.52

1.62

1.43 1.55

1.41 1.42 1.49 1.54

1.53

1.67

1.57

0.0

0.5

1.0

1.5

2.0

2.5

6" 10" 13" 20" 6" 10" 13" 20"

Passageway Configuration

Mean Time in Seconds

In Out

p < .04

Low Motivation High Motivation

Hatch Disposal Location:
14 

Figure 19 

Average Individual Subject Egress Time 

Passageway Configuration X Subject Waist Size Interaction

0.0

0.5

1.0

1.5

2.0

2.5

23-31 32-34 35-38 39-41 41-62

Waist Size in Inches

Mean Time in Seconds

6" 10" 13" 20"

p = .005

Figure 20 

Average Individual Subject Egress Time 

Passageway Configuration X Subject Waist Size X Subject Gender Interaction

0.0

0.5

1.0

1.5

2.0

2.5

23-31 32-34 35-38 39-41 41-62 23-31 32-34 35-38 39-41 41-62

Subject Waist Size in Inches

Mean Time in Seconds

6" 10" 13" 20"

Males Females

p = .002
15

Figure 21 

Average Individual Subject Egress Time 

Passageway Configuration X Subject Age X Subject Gender Interaction

0.0

0.5

1.0

1.5

2.0

2.5

18-22 23-32 33-42 43-52 53-65 18-22 23-32 33-42 43-52 53-65

Subject Age in Years

Mean Time in Seconds

6" 10" 13" 20"

p<.001

Males Females

Figure 22 

Relative Magnitude of Effects 

on Average Individual Subject Egress Time

0

5

10

15

20

Hatch Location Group Density Subject Height Group

Motivation

Passageway

Configuration

Design Factor

Interactions

Subject Gender Subject Age Within Subject

Interactions

Subject Waist

Size

Egress Factors

Percentage of Total Effect
16 

Figure 23 

Individual Subject Egress Time 

Trial Main Effect

1.0

1.2

1.4

1.6

1.8

2.0

Trial 1 Trial 2 Trial 3 Trial 4

Mean Time in Seconds

P < .63 

Figure 24 

Individual Subject Egress Time

Egress Trial By Group Motivation Interaction

1.45

1.63

1.55

1.49 1.54 1.53

1.47

1.49

1.0

1.2

1.4

1.6

1.8

2.0

Trial 1 Trial 2 Trial 3 Trial 4

Mean Time In Seconds

Low High

p < .0004

Group Motivation Level:
17

Figure 25 

Average Individual Subject Egress Time

 Trial by Group Motivation by Hatch Disposal Location Interaction

1.0

1.2

1.4

1.6

1.8

2.0

Trial 1 Trial 2 Trial 3 Trial 4 Trial 1 Trial 2 Trial 3 Trial 4

Mean Time in Seconds

Low High

Hatch In Hatch Out

Group Motivation:

p = .03

Figure 26 

Average Individual Subject Egress Time 

Trial by Passageway Configuration by Hatch Disposal Location Interaction

1.0

1.2

1.4

1.6

1.8

2.0

Trial 1 Trial 2 Trial 3 Trial 4 Trial 1 Trial 2 Trial 3 Trial 4

Mean Time in Seconds

6" 10" Passageway Configuration: 13" 20"

Hatch In Hatch Out

p = .007
18 

this formula, with the only departure being the Trial 3 

high-motivation group times in the outside hatch disposal 

location condition. These trials appeared to be atypically 

faster than the other high- (and low-) motivation trials, 

suggesting that the 2-way interaction would likely be more 

robust, as a rule, than evidenced here. Again, these effects 

were reminiscent of those seen in the first (naïve subject) 

trial of this study, although the motivation effects seen 

there were based on between-subject differences that did 

not include within-subject changes in performance. The 

(3-way) egress trial by passageway configuration by hatch 

disposal location interaction effect resulted from improved 

individual egress times with progressive experience at all 

passageway configurations, although the individual egress 

times in the more restrictive passageway configurations 

were longer and more variable across the four evacuation 

trials. This effect, in a manner similar to that found in 

the first-trial analysis, was linked to the effects of errant 

hatch disposal locations, which produced impediments 

to egress. In sum, these results also mirror those found 

for the first (naïve subject) trial, and they generally replicate much of the effects previously reported elsewhere 

(cf., McLean, 2001).

DISCUSSION

The history of evacuation research involving the 

Type-III overwing exit has been filled with a diversity of 

protocols and methodologies. The relative value of these 

different approaches has sometimes been in question, not 

necessarily as a matter of good science, but whether or not 

the results could be used to model real world emergency 

evacuations, i.e., those involving naïve passengers in complex emergency situations. Such questions have often 

focused on the experimental designs used in the relevant 

studies, specifically the application of repeated-measures 

protocols and/or practice evacuations to reduce human 

performance variability when attempting to discern the 

effects of differences in airplane design and/or emergency 

procedures. The argument has been that only through the 

use of typical passengers in unprepared evacuations could 

valid results be obtained. 

The design of the current study was intended to 

address this issue by utilizing a large number of naïve 

(inexperienced) subjects in a complex evacuation research 

protocol designed to achieve realism and high fidelity. 

The question of interest involved the speed of egress that 

subjects would be able to realize through the available 

escape route, i.e., the Type-III exit, and the variations 

in individual egress speed produced by changes in airplane configuration and operation/disposal location of 

the escape hatch. A motivational treatment (financial 

incentives) was also included for half the subject groups 

to induce the competition and aggressive behavior, seen 

in life-threatening emergencies, which had been argued 

as producing qualitatively distinctive egress. Finally, 

professional flight attendants were provided to manage 

the evacuations, as would be done in actual emergency 

evacuations. The outcome was to produce a variety of 

experimental conditions, each of which provided a piece 

to complete the puzzle of how emergency evacuations 

through the Type-III exit are affected by configural, 

procedural, and personal variables. 

The results of only the first trial for each group in the 

study are described in McLean et al. (2002), which identified the effects of subject attributes (waist size, gender, 

and age) and inexperience as the primary influences on 

the speed of evacuations through the Type-III exit. The 

effects of airplane configuration and hatch operation/

disposal paled by comparison. Not unexpectedly, the 

significant main effects of subject waist size, gender, and 

age found in that first (naïve-subjects) analysis were fully 

replicated in the results from all the evacuation trials, 

as reported here. 

A small but significant main effect on speed of egress 

was also produced by differences in passageway configuration; i.e., egress speed was generally reduced as single 

passageways became more restrictive with respect to access 

to the Type-III exit. Importantly, the effects of restrictive passageway configurations were confounded with the 

problematic effects of inside hatch disposal, as the hatch 

sometimes became dislodged from its resting place on 

the seat to become an impediment to the evacuation. In 

contrast to the more restrictive single passageway configurations, the 6” dual passageway configuration produced the 

second fastest evacuations, on average, as the additional 

passageway allowed dual subject flow. 

The passageway configuration by subject age by subject 

gender interaction effect was also a replication of the 

first trial effect, as older females, in particular, had egress 

difficulty in the more restrictive passageway configurations. A main effect of subject group motivation was also 

evidenced in this more expansive within-subjects analysis, 

even though the absolute difference in mean individual 

speed of egress between group motivation levels was 

smaller than that for naïve individual speed of egress in 

Trial 1. The added significance lies again in the much 

larger number of individual observations and the added 

statistical power this produces. The same can be said of the 

newly-found passageway configuration by subject waist 

size interaction effect and the passageway configuration 

by subject waist size by subject gender interaction effect, both of which appear to depend on the difficulties 

experienced by heavier subjects, particularly females, in 

the more restrictive passageway configurations, as was 

shown in the previous non-significant interaction effects 
19

in Trial 1. Thus, the average effects of the independent 

variables and the physical attributes of the subjects in the 

second analysis were little changed from the effects found 

in the first-trial (naïve subjects) analysis. Comparison of 

the relative magnitude of effects found in Figure 43 in 

McLean et al. (2002) with Figure 22, herein, confirms 

these strong similarities. 

The cumulative effects of evacuation experience also 

conformed to expectations, as the low-motivation group 

subjects were able to enhance their egress performance 

continually throughout the evacuation trials, whereas 

the aggressiveness and behavioral variability found for 

the high-motivation subjects generally interfered with 

the potential for improvement. This effect occurred in 

spite of the effective passenger management techniques, 

employed by the flight attendants during the evacuations, 

which appeared to serve the intended purpose of keeping 

(high-motivation) subjects from jamming the exit opening and creating blockades. General improvements in 

individual egress times were the norm for most subjects in 

all passageway configurations, although two groups were 

relatively slow on Trial 4, one in the 6” passageway configuration with the hatch placed inside and one in the 10” 

passageway configuration with it thrown outside. These 

two groups appear responsible for the trial by passageway 

configuration by hatch disposal location interaction effect, 

which would generally be seen as atypical. 

CONCLUSION

The use of the initial between-subjects, or this second 

within-subjects, analysis to answer the research questions 

proved not to be particularly discriminative with respect 

to the quality of the results, as the extensiveness of the 

initial between-subjects analysis (McLean et al., 2002) 

eliminated statistical shortcomings. Importantly, this 

much more extensive repeated-measures design provided 

a solid replication of that first-trial analysis; however, its 

enormous amount of statistical power could easily mislead 

with respect to the practical significance of the results. 

This would be true in cases where statistical significance 

was used exclusively as the rationale for application of 

the findings, without regard to the absolute differences 

in effects produced by the variable(s) of interest. 

The effects on evacuation performance described 

above replicate fully the effects found in the first-trialonly results. In sum, the effects of the subjects’ physical 

attributes were shown to be particularly significant with 

respect to speed of egress, as were the cumulative effects 

of high-motivation (financial incentives). In contrast, the 

cabin interior (passageway) configuration at the Type-III 

overwing exit was again shown to be of limited significance 

to emergency evacuation speed, although the interactions 

of passageway configuration with subjects’ physical attributes revealed that ergonomic considerations related 

to restrictive passageway configurations must continue to 

be acknowledged in the design of airplane cabin interiors 

adjacent to the Type-III exit. Operation and disposal 

location of the Type-III exit hatch also interacted with 

passageway configuration, as well as with subject motivation level, to indicate that eliminating the hatch from the 

cabin interior adjacent to the Type-III exit is central to 

assuring efficient egress, especially with regard to more 

restrictive passageway configurations. 

The ability of subjects to profit from egress experience 

was shown via the interaction effects of egress trial with 

passageway configuration, hatch disposal location, and 

subject motivation level, which showed reduced individual 

egress time as the trials progressed, as compared with the 

same interaction effects of the subjects on the first trial. 

Ostensibly, subjects became more aware of evacuation 

contingencies and associated behavioral requirements as 

their experience grew. Provision of the flight attendants 

also appeared to enhance evacuation performance by keeping subjects under better control (on task) during the 

evacuation trials. This appeared to bring a higher degree 

of regularity to the high-motivation results that might 

otherwise prove elusive in actual emergencies without the 

benefit of trained assistance. Both of these factors highlight 

the need for proper passenger management, better passenger awareness of the airplane emergency environment 

and appropriate evacuation/survival techniques, as well as 

actual experience, where possible. As passengers become 

more knowledgeable about the emergency environment 

and what to do when faced with it, less reliance on design parameters should be needed to achieve successful 

evacuation/survival outcomes. 

REFERENCES

Corbett, CL, GA McLean, and JE Whinnery. Accessto-Egress II: Subject Management and Injuries in 

a Study of Emergency Evacuation Through the 

Type-III Exit, DOT/FAA/AM-03/15, Office of 

Aerospace Medicine Report, October 2003.1

Department of Transport, Aircraft Accident Investigation 

Branch, Report on the Accident to Boeing 737-

236 Series 1, G-BGJL at Manchester International 

Airport on 22 August 1985, (AAIB Report 8/88), 

London, 1998.

1

This publication and all Office of Aerospace Medicine technical 

reports are available in full text from the Civil Aerospace Medical 

Institute publication Web site: http://www.cami.jccbi.gov/aam400/index.html 
20

McLean, GA. Access-to-Egress: A Meta-Analysis of 

the Factors That Control Emergency Evacuation 

Though the Transport Airplane Type-III Overwing 

Exit, Office of Aviation Medicine Report, DOT/ 

FAA/AM-01/2, Washington, DC: FAA, January 

2001. 1

McLean, GA, CL Corbett, K Larcher, J McDown, DA 

Palmertion, KA Porter, RM Shaffstall, and RS 

Odom. Access-to-Egress I: Interactive Effects of 

Factors That Control The Emergency Evacuation 

Of Naïve Passengers Through The Transport Airplane Type-III Overwing Exit, DOT/FAA/AM02/16, Office of Aerospace Medicine Report, 

August 2002. 1

McLean, GA, CL Corbett, and MH George. Passenger 

Management Strategies for Emergency Egress 

Through Airliner Overwing Exits, Aerospace 

Medical Association Annual Scientific Meeting, 

Detroit, MI, May 1999.

McLean, GA and MH George. Aircraft Evacuations 

Through Type-III Exits II: Effects of Individual 

Subject Differences, Office of Aviation Medicine 

Report, DOT/FAA/AM-95/25, Washington, DC: 

FAA, August 1995.1

Muir, H, D Bottomley, and J Hall. Aircraft Evacuations: 

Competitive Evacuations in Conditions of NonToxic Smoke, Civil Aviation Authority, UK, CAA 

Paper 92005, March 1992.

National Transportation Safety Board, Aircraft Accident 

Report, Runway Collision of USAir Flight 1493, 

Boeing 737 and Skywest Flight 5569 Fairchild 

Metroliner, Los Angeles International Airport, 

Los Angeles, California, (NTSB/AAR-91/08), 

Washington, DC: NTSB, February 1, 1991. 

SPSS Base 10.0 Applications Guide, SPSS Inc., Chicago, 

Il, 1999.