Garnet A. McLean

David A. Palmerton

Cynthia L. Corbett

Kenneth G. Larcher

Jerry R. McDown

Civil Aerospace Medical Institute

Federal Aviation Administration

Oklahoma City, OK 73125

August 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-04/12 Simulated Evacuations 

Into Water
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 

Report No. 

DOT/FAA/AM-04/12

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

4. Title And Subtitle 

Simulated Evacuations Into Water 

5. Report Date 

August 2004 7. Author(s) 

McLean GA, Palmerton DA, Corbett CL, Larcher KG, McDown JR 

9. Performing Organization Name and Address 

FAA Civil Aerospace Medical Institute 

P.O. Box 25082 

Oklahoma City, OK 73125

8. Performing Organization Report No. 

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. 

13. Type of Report and Period 

Covered 

15. Supplemental Notes 

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

14. Sponsoring Agency Code 

16. Abstract 

Introduction. Transport airplanes are required to be assessed for ditching capability in the FAA type-certification 

process. This includes the airplane’s emergency evacuation potential, i.e., the ability of passengers to escape the 

airplane after it lands on water. Actual emergency data to support ditching certification are not available; there 

have been questions as to whether evacuation flow rates onto land are appropriate for use in ditching-related 

flotation time computations. Simulated evacuations from platforms into the CAMI survival tank were conducted 

to obtain passenger flow rate data that can be used to support the certification process. Methods. A 12’ x 12’ 

platform was placed next to the tank. Platform (exit sill) heights of 9”, 2’, 4’, and 6’ were employed; flotation seat 

cushions and inflatable life vests were used as individual flotation aids. Four subject groups performed 3 simulated 

evacuations at each platform height through a Type-I exit-sized opening; 4 other groups similarly used a Type-A 

exit-sized opening. Results. A significant effect (p<.001) of platform height above the water was found, as 

increasing heights resulted in monotonic decreases in flow rate. A significant effect (p<.01) of flotation device type 

was also found, with flotation seat cushions producing the lowest flow rates, followed next by life vests that were 

uninflated until entry into the water, and then life vests that had been inflated before leaving the platform. Finally, 

the Type-A exit-sized platform configuration was significantly faster than was the Type-I configuration (p<.05). 

Conclusion. These effects suggest that in the best conditions, passenger flow rates into water are much like those 

onto land. However, the platform height effects suggest that airplane attitude in the water may be important, as is 

exit size. The use of flotation seat cushions as flotation aids should be a last resort. 

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 

12

22. Price 

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

iii

ACKNOWLEDGMENTS

The authors gratefully 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. Among all those who contributed, special thanks go to our research support staff:

April Baker

Rick Butler 

Donna Cosper 

David DeSelms

Rick DeWeese

Dave Dyer

Ronnie Minnick

Bryan Provine

Lori Samuel

Robert Shaffstall 

Steve Veronneau 

James Whinnery 

Greg Winters

1

SIMULATED EVACUATIONS INTO WATER

INTRODUCTION

Certification procedures for transport airplane 

evacuation capability are well defined in Federal Aviation Regulations; however, evacuation procedures for 

ditching scenarios, in which passengers must evacuate 

into life rafts or into the water, are not specified in those 

requirements. Part 25.801(d) of 14 CFR (1) states, “it 

must be shown that, under reasonably probable water 

conditions, the flotation time and trim of the airplane 

will allow the occupants to leave the airplane and enter 

the liferafts required by§25.1415 (1).” 

This requirement has generally been demonstrated via 

the use of a flotation-time analysis for each new airplane 

type. The proposed design and operation of new, very 

large transport airplanes, e.g., double-deck airplanes that 

will conduct many extended over-water operations, raise 

questions regarding some of the assumptions in the flotation-time analyses. Specifically, the distance of very large 

airplane lower deck exit sills above the water line has 

been predicted to range in a successful ditching from just 

a few inches to about 6 ft. This may create significant 

deviations from the passenger flow rates into the water 

assumed historically for transport airplanes, especially 

those caused in part by the speed with which passengers 

can vacate the area immediately adjacent to the aircraft 

exit once they have entered the water. Such deviations 

may also exist for new narrow-body airplane types with 

long fuselages, for which unfavorable flotation attitudes 

could also produce exit sill heights from water level to 

several feet, especially for exits at the ends of the fuselage. 

Differences in personal flotation devices and their modes 

of operation can add to such variances, as can the exit 

type through which passengers must egress. 

To provide information relative to these certification 

questions, the Civil Aerospace Medical Institute (CAMI) 

Protection and Survival Research Laboratory conducted 

a study using its water survival research tank to evaluate simulated egress into water. Subjects jumped from 

a platform, configured with a simulated Type A (42” 

wide) dual-lane floor-level exit or a simulated Type I 

(24” wide) single-lane floor-level exit, erected at heights 

of 0.75, 2, 4, and 6 feet above the surface of the water. 

Three different personal flotation device conditions were 

also investigated; subjects jumped into the water: 1) while 

holding typical transport airplane flotation seat cushions, 

2) while wearing an inflatable life vest (inflated) approved 

to Technical Standard Order (TSO-C13), or 3) while 

wearing the TSO-approved life vest (uninflated) until 

after entering the water and then inflating it. 

The goal of the research project was to provide bestcase estimates of the egress times (flow rates) into water 

that could be expected through each of the simulated exit 

types, at each of the simulated exit sill heights, for each 

of the different personal flotation device conditions. 

METHODS

Experimental design. Four groups of 20 to 31 

(mean = 25) participants completed 12 experimental 

evacuation trials in a 3 (flotation device) by 4 (platform 

height) repeated-measures design (Table 1), using either 

Table 1. Experimental Design 

Flotation device 

order

S 

VU 

VI 

VI 

S 

VU

S 

VI 

VU

VU 

S 

VI 

Group 1 

platform order 

 

.75’ 

 

2’

 

4’

 

6’

Group 2 

platform order 

 

6’

 

4’

 

2’

 

.75’ 

Group 3 

platform order 

 

4’ 

 

6’

 

.75’ 

 

2’

Group 4 

 platform order 

 

2’

 

.75’ 

 

6’

 

4’

S = Seat cushion / VI = Vest inflated / VU = Vest uninflated 
2 

the Type A or Type I exit. Flotation-device and platformheight conditions were counterbalanced within each group 

to minimize bias. 

Subjects. Two hundred medically-fit participants, 

ranging in age from 18 to 50 years of age, weighing less 

than 300 lbs. each, divided almost evenly with respect to 

gender (m = 95 / f = 105), and with the ability to swim 

2 lengths of the CAMI survival tank, were employed in 

the study. They wore long pants, a T-shirt style top, and 

shoes; they also wore a TSO C-13 approved inflatable 

life vest or clutched a typical transport airplane flotation 

seat cushion. 

Safety Personnel. Two Red Cross/CPR-certified lifeguards were stationed at the edge of the water alongside 

the survival tank near the platform during all trials and a 

SCUBA diver was positioned in the water at the side of 

the platform for water safety concerns. Four additional 

research personnel were stationed around the pool to 

provide assistance in the unlikely event that a subject 

needed to be helped out of the water.

Apparatus. A 144 ft2 adjustable-height platform (Figure 1), configured to produce either a simulated Type A or 

Type I exit, was constructed alongside the CAMI survival 

tank. The platform was essentially 12’ x 12’ square, except 

that a 4’ x 4’ section at the left rear of the platform was 

removed and replaced with stairs, with the removed section 

being attached to the center of the platform at the edge 

of the survival tank to form a protruding “passageway” 

that participants used to approach the simulated exit. A 

3-ft high side rail was erected around the platform for 

participant safety, except that the rail did not enclose the 

front edge of the section protruding over the water. 

The side rails along this section of the platform were 

fitted with foam blocks to exactly establish the width of 

the passageway/exit at either 24” or 42”, depending on 

the experimental condition (Figure 2). The sliding doors 

of the survival tank facility were nestled against the side 

edges of the protruding platform section to serve as a 

simulated fuselage and to preclude participants from seeing the activity in the water adjacent to the platform until 

it was their turn to jump. The platform was erected at 4 

different heights (0.75, 2, 4, and 6 ft) above the water 

for each participant group; this height was readjusted 

between trials after subjects had completed their egress 

trials for each height. The minimum (0.75 ft) platform 

height above the water was as near to the surface of the 

water as could be physically achieved by the apparatus.

Two flotation devices were used to create 3 flotationdevice conditions, as participants: 1) wore a pre-inflated 

life vest when jumping through the exit and entering 

the water, 2) wore a non-inflated life vest when jumping 

through the exit that they inflated upon entering the water, 

and 3) clutched the flotation seat cushion as they jumped 

through the exit and entered the water. Video cameras 

with time-code generators were strategically located to 

record/time participants jumping from the platform into 

Figure 1. Platform Configuration
3

the water; underwater activity was also recorded by video 

camera from below (Figure 3). 

Procedure. Participants completed the necessary 

paperwork/medical screening and were tested for their 

ability to swim 2 lengths of the CAMI survival tank 

before being allowed to enter the experimental phase of 

the study. They were then briefed about the scenario to 

be followed for the simulated evacuations, i.e., they were 

flying in an airplane that had an emergency landing on 

water and was rapidly sinking. They had to “get out” by 

jumping as fast as possible through the exit into the water 

and moving away from the airplane as quickly as possible 

toward a life raft (placed across the survival tank) that had 

been deployed in the water. Importantly, however, they 

were also told that they must not jump onto any of their 

fellow passengers who were already in the water. They 

were then shown how to operate an inflatable life vest 

(Figure 4), as well as the proper way to hold a flotation 

seat cushion (Figure 5). Once the briefings were completed 

and any questions answered, they were provided with 

either a life vest or a flotation seat cushion and directed 

to the platform, where they climbed the stairs and formed 

either a dual-lane queue to the simulated Type-A exit or 

a single-lane queue to the simulated Type I exit. (Note 

that only 1 exit type was used by any group; in contrast, 

each group performed in all 3 flotation device conditions 

and at all 4 platform heights.) 

Each trial began with a verbal start signal (GO!), whereupon the participants began to jump into the water, inflate 

their life vests (if necessary), and kick/swim/move quickly 

away from the area beneath the exit toward the life raft 

across the survival tank to allow succeeding participants 

to egress as quickly as possible. After each experimental 

trial was completed, participants climbed from the tank, 

received the flotation device appropriate for the next trial, 

and returned to the platform to regroup for the next trial. 

After the 3 trials at any 1 platform height were completed, 

participants waited at the shallow end of the tank for the 

platform to be reconfigured to the next height. 

RESULTS

Participant group sizes ranged from 21 to 31 

(mean = 25), making group times inappropriate for 

comparison. Consequently, average individual egress times 

were calculated. In general, individual egress times into the 

water for the simulated Type A (dual-lane) passageway/

exit were somewhat shorter than those achieved with the 

simulated Type I (single-lane) passageway/ exit, owing to 

the ability of the larger passageway/exit to accommodate 

simultaneous or staggered egress. The small (0.16 sec) 

difference was marginally significant (p<.05). No interactions of exit type were found with either platform height 

or flotation device. 

Figure 2. Passageway/Exit Restriction Produced by Foam Blocks
4 

Figure 3. Underwater Observation

Figure 4. Proper Method to Inflate Life Vest Figure 5. Proper Method to Hold Seat Cushion 
5

The effects of platform height (p<.0001) on individual 

egress were more robust, with egress times increasing 

0.71 seconds per person, on average, as the height of the 

platform was increased from 9 in to 6 ft above the water. 

Post hoc analyses showed that both the 4-ft and 6-ft 

platform heights produced statistically slower individual 

egress than that achieved at 2 ft and below, and the 6-ft 

high platform yielded significantly slower egress than that 

at 4 ft (Duncan’s; p<.05). Figures 6 and 7 show the effects 

of platform height for each exit type. A significant effect 

of flotation device type on individual egress time was also 

found (p<.01), with the use of flotation seat cushions 

resulting in individual egress that was 0.25 sec per person 

slower, on average, than egress with inflatable life vests. No 

interactions of flotation device type and platform height 

were found, although a 3-way interactive trend (p<.06) 

of exit type, platform height, and flotation device type 

was displayed, resulting from particularly slowed egress 

for participants using the inflated life vest through the 

Type A, but not the Type I, exit with increasing platform 

height. Figures 8 and 9 show the effects of flotation device 

type for each exit type. 

DISCUSSION

The effects of platform height and type of flotation 

device on individual egress time into the water generally 

conformed to expectation, although the differences in individual egress time related to single-lane versus dual-lane 

participant flow on the platform and into the water were 

somewhat smaller than anticipated. Irrespective of exit 

type, increasing platform height resulted in longer times 

for participants to jump into the water, much as would 

be seen at any municipal swimming pool as the height 

of the diving board increases. Such effects can be related 

to the fear generally associated with jumping from high 

places, although the instruction that participants were 

given about being sure not to jump onto another person 

already in the water also appeared to play a part. 

As the platform height increased, so did the time that 

participants were underwater or recovering from the jump, 

making an additional delay necessary for those on the 

platform to be sure that the prior jumpers were out of 

the way. This effect occurred for both the Type A and 

Type I passageway/exit configurations. However, with 

participants being able to form only a single lane queue to 

approach the Type I exit and having a wide landing area in 

the water beneath the platform, this height-related need 

to wait for prior jumpers to clear the area was minimized 

relative to the Type A exit configuration. 

The Type A exit with the dual-lane queue allowed 

relatively faster individual egress into the water, resulting 

in a greater number of jumpers in the landing area at any 

one time, although this produced a greater need to scan 

the water to make sure the landing area was clear before 

jumping. While the difference in hesitation time related 

to the combination of exit type and platform height was 

statistically insignificant, it appeared to form much of the 

basis for the trend toward a 3-way interaction of exit type, 

platform height, and flotation device type. This trend 

was additionally dependent on the differential delays 

in getting away from the landing area produced by the 

flotation seat cushion and the uninflated life vest, relative 

to the pre-inflated life vest. 

The effects of flotation device type on individual egress 

times into water appeared to result from both the difficulty participants had moving away from the landing 

area and the time they spent under water after jumping. 

The lack of inflation upon entering the water with the 

uninflated life vest allowed participants to plunge much 

further into the water, increasing their underwater time 

in the landing area and, especially when coupled with 

dual-lane participant flow, resulted in added delays to 

participants on the platform who had to make sure the 

water was clear before jumping. The delay occurred even 

though they could use their arms for swimming, which 

otherwise should have made for a quick getaway from 

the landing area.

Like the pre-inflated life vest, immediate flotation 

upon entering the water was provided by the flotation 

seat cushion, although the seat cushion, in particular, 

made moving through the water difficult. This occurred 

because the cushion formed somewhat of a barrier that 

had to be pushed through the water to move away from 

the landing area, and the participant’s arms had to be 

locked around the cushion, eliminating any ability to 

use them for swimming. This resulted in a ki cking -only

mode of locomotion. 

In contrast, the pre-inflated life vest provided the positive benefits of having ready flotation upon entering the 

water and it allowed participants full use of their arms 

to swim easily and move away from the landing area 

with greater speed. This combination of attributes gave 

the pre-inflated life vest a relative advantage, especially 

when participants were using the Type-A dual-lane exit 

configuration, and made it the preferred type of flotation device. 

Application of these results to operational and certification decisions would appear rather straightforward, 

albeit with a caveat or two. First, the operational issue 

of life vest pre-inflation has long been a question within 

the industry. The results presented here suggest that, in 

terms of escape and moving away from a ditched airplane, 

pre-inflation is a good idea. In mitigation of these findings are accident reports and personal accounts of crash 

survivors, which indicate that passengers have been and 
6 

6

Figure 6. Platform Height Effects With the Type A Exit

2.01

1.86

1.58

1.43

0.0

0.5

1.0

1.5

2.0

2.5

9" 2' 4' 6'

Platform Height

Average Time in Seconds per Person

Figure 7. Platform Height Effects With the Type I Exit

2.37

1.96

1.73

1.51

0.0

0.5

1.0

1.5

2.0

2.5

9" 2' 4' 6'

Platform Height

Average Time in Seconds per Person
7

10

Figure 8. Flotation Device Effects With the Type A Exit 

1.89

1.71

1.55

0.0

0.5

1.0

1.5

2.0

2.5

Vests Inflated Vests Uninflated Seat Cushions

Flotation Devices

Average Time in Seconds per Person

Figure 9. Flotation Device Effects With the Type I Exit 

2.06

1.83 1.78

0.0

0.5

1.0

1.5

2.0

2.5

Vests Inflated Vests Uninflated Seat Cushions

Flotation Devices

Average Time in Seconds per Person
8

may become trapped inside the airplane should they inflate 

their vests and the exits then sink below water line. Given 

both arguments, it would appear that a well-chosen course 

of action would be to maintain the vests in an uninflated 

condition until the passenger begins to jump from the 

airplane exit, pulling the inflation handles in mid-air to 

create life vest buoyancy before hitting the water. 

In addition, in terms of flotation-time analyses and 

certification decisions, it must be noted that the environmental conditions under which these experimental 

trials were run were exemplary. Participants were not 

forced to encounter rough seas, adverse airplane attitudes, 

disrupted cabin interiors, floating debris, darkness, or 

extreme temperatures (reasonably probable water conditions of §25.801(d)), all of which would likely reduce 

evacuation flow rates significantly. Likewise, participants 

did not experience the disruptive physical, psychological, 

and emotional effects of having an emergency landing 

on water. These, too, would impair decision-making and 

reduce evacuation flow rates. Thus, the results presented 

here may be thought of as the upper bounds of what 

could be expected with regard to emergency evacuation 

flow rates into water environments, and significant reductions in estimated flow rate below these optimum values 

should be made unless and until further work has more 

properly defined the effects of such known emergency 

contingencies.

REFERENCES 

Title 14, US Code of Federal Regulations, Part 25, 

Sections 801(d) and 1415. Washington, DC: US 

Government Printing Office, 2003.