Safety Research on Type III Exit Operation in Aircraft Cabins: Cranfield University Study

1. Recent Transport Canada safety research at Cranfield University Rebecca L. Wilson, Lauren J. Thomas & Helen C. Muir Human Factors Group School of Engineering Cranfield University, UK

2. Recent Research • Considerable research has been conducted into the operation of the Type III exit, however much of this work has been conducted in a 3x3 configuration. • Relatively little is known about whether the research findings generalise to a 2x2 configuration. • Transport Canada have commissioned three preliminary studies into the operation of the Type III exit in a 2x2 configuration.

3. Study 1:- 2x2 and 3x3 cabin configuration • Test facility was a Boeing 737 cabin simulator configured in either: • 3x3 or 2x2 configuration • 10” or 13” VP in Type III exit row • Participants: • 24 independent groups of up to 20 participants, six groups per condition. • Dependent variable: • Egress time • Exit availability time

4. Boeing 737 cabin simulator 3x3

5. Boeing 737 cabin simulator 2x2

6. Procedure • Participants were greeted by a researcher trained and dressed as cabin crew. After check-in, participants boarded the cabin simulator. • Seats for each group were pre-allocated according to a random seating plan. • Each group of participants were given a typical pre-flight safety briefing. • A minimal briefing was also provided to the passenger seated at the Type III exit (Cobbett, Liston & Muir, 2001). 2x2 and 3x3

7. Evacuations • On completion of the safety briefing, passengers heard a recording of engine noise, followed by an announcement from the Captain to “Undo your seatbelts and get out!” • The cabin crew member then instructed passengers to open and move towards the Type III exit. • Throughout the evacuation, the cabin crew used assertive, positive and concise commands to encourage passengers to move as quickly as possible (Muir & Cobbett, 1996). 2x2 and 3x3

8. Results • Data on evacuation times was extracted from video footage recorded outside the Type III exit. Each participant was deemed to have evacuated when both feet were on the wing. • Data were available from a total of 24 evacuations – six trials within each condition. • Since the group size varied due to non attendance, all evacuation time analyses used only the times for the first 15 people to evacuate through the exit. 2x2 and 3x3

9. Mean evacuation times 1st 15 (in secs) 2x2 and 3x3

10. Evacuation results • Inferential statistical analysis showed that there were statistically significant differences due to the seating configuration. • Participants evacuated quicker in the 2x2 configuration than the 3x3 configuration. This effect may be due to passageway length. The result was unlikely to have arisen by chance. • There were no statistically significant differences in evacuation times due to vertical projection, nor an interaction between seating configuration and vertical projection. 2x2 and 3x3

11. Mean exit availability times (in secs) 2x2 and 3x3

12. Exit availability results • Inferential statistical analysis indicated no significant differences in the time taken to make the exit available due to seating configuration or vertical projection. 2x2 and 3x3

13. Study 2:- Modification to operating handle • Test facility was a Boeing 737 cabin simulator configured in either: • 3x3 configuration or 2x2 configuration • Exit operating handle configured in either: • Retracted (conventional) mechanism or fixed (modified) mechanism • 40 participants: • Tested individually. • Repeated and counterbalanced on handle type • This paper reports data from naïve participants only • Dependent variables; • Egress time and exit availability time Handle mods

14. Exit handle modifications Handle mods

15. Procedure • Participants were greeted by a researcher trained and dressed as cabin crew. After check-in, participants boarded the cabin simulator. • Each participant sat in the seat adjacent to the Type III exit. • Participant was given a typical pre-flight safety briefing. • In addition, participants received an in-depth individual briefing on their emergency duties (i.e. checking outside, heavy hatch, mode of operation). Handle mods

16. Evacuations • On completion of the safety briefing, passengers heard a recording of engine noise, followed by an announcement from the Captain to “Undo your seatbelts and get out!” • The cabin crew member then instructed the passenger to open and move towards the Type III exit. • Throughout the evacuation, cabin crew used assertive, positive and concise commands to encourage the passenger to move as quickly as possible (Muir & Cobbett, 1996). Handle mods

17. Results • Data on evacuation times was extracted from video footage recorded outside the Type III exit. A participant was deemed to have evacuated when both feet were on the wing. • Only the results from the first trial – with naïve participants - are reported here. • Data were available from a total of 40 evacuations – 10 evacuations within each condition. Handle mods

18. Mean evacuation times ppn (in secs) Handle mods

19. Evacuation results • Inferential statistical analysis showed that there were statistically significant differences due to the seating configuration. • Individual participants evacuated quicker in the 3x3 configuration than the 2x2 configuration. This effect was unlikely to have arisen by chance. • There were no statistically significant differences in evacuation times due to handle modification, and no interaction between handle modification and seating configuration. Handle mods

20. Mean exit availability times (in secs) Handle mods

21. Exit availability results • Inferential statistical analysis showed that there were statistically significant differences due to the seating configuration. • Participants made the exit available more quickly in the 3x3 configuration than the 2x2 configuration. This effect was unlikely to have arisen by chance. • There were no statistically significant differences in exit availability times due to handle modification, nor an interaction between handle modification and seating configuration. Handle mods

22. Study 3: - Type III hatch disposal • Test facility - Boeing 737 cabin simulator in a 2x2 configuration. • Type III exit hatch configured as either: • Conventional “plug” style hatch or “up and over” ADH • 80 participants, tested individually. • Three ‘stooge’ passengers around the exit row to add a degree of pressure on participants to evacuate quickly. • Dependent variable: egress times and exit availability times Hatch disp

23. Type III exit hatch with ‘plug’ design Hatch disp

24. Type III exit hatch with ADH mechanism Hatch disp

25. Procedure • Participants were greeted by a researcher trained and dressed as cabin crew. After check-in, participants boarded the cabin simulator. • Each participant sat in the seat adjacent to the Type III exit. • Participants were given a typical pre-flight safety briefing. • A minimal briefing was also provided to the passenger seated at the Type III exit (Cobbett, Liston & Muir, 2001). Hatch disp

26. Evacuations • On completion of the safety briefing, passengers heard a recording of engine noise, followed by an announcement from the Captain to “Undo your seatbelts and get out!” • The cabin crew member then instructed passengers to open and move towards the Type III exit. • Throughout the evacuation, cabin crew used assertive, positive and concise commands to encourage the passenger to move as quickly as possible (Cobbett & Muir, 1996). Hatch disp

27. Results • Data on evacuation times was extracted from video footage recorded outside the Type III exit. The participant was deemed to have evacuated when both feet were on the wing. • Data were available from a total of 40 evacuations – 10 evacuations within each condition. Hatch disp

28. Mean evacuation times ppn (in secs) Hatch disp

29. Evacuation results • Inferential statistical analysis showed that there were statistically significant differences between hatch designs. • Participants evacuated significantly faster when the hatch had an ADH mechanism than when it was a conventional ‘plug’ design. This effect was unlikely to have arisen by chance. Hatch disp

30. Mean exit availability times (in secs) Hatch disp

31. Exit availability results • Inferential statistical analysis showed that there were statistically significant differences between hatch designs. • Participants made the exit available more quickly when the hatch had an ADH mechanism than when it was a conventional ‘plug’ design. This effect was unlikely to have arisen by chance. Hatch disp

32. Conclusions • All results relate to preliminary experimental work, but raise interesting issues regarding Type III exits in smaller airframes. • Findings from the second study directly contradict results in first study. With small groups, overall evac time in 2x2 configurations were quicker. With individuals, 3x3 was quicker. • It may be that for small groups, the shortened passageway length in 2x2 configuration offset the lack of headroom. • With individual tests, pax were already in exit row, therefore headroom a more important factor. Hatch des

33. Conclusions • The modification to the operating handle had no effect on the time taken to operate the exit, although this may be a function of the in-depth exit briefing that was provided to passengers. • However, there was an effect for configuration, such that participants were able to make the exit available more quickly in a 3x3 configuration. This again may be due to the additional headroom available for the exit operator. • ADH results replicate previous research on the up and over mechanism in 3x3 configurations.