Safety Study: Emergency Evacuation of Commercial Airplanes

This is an abstract from the Safety Board's report and does not include the Board's rationale for the conclusions and recommendations. Safety Board staff is currently making final revisions to the report from which the attached conclusions and recommendations have been extracted. The final report and pertinent safety recommendation letters will be distributed to recommendation recipients and investigation parties as soon as possible. The attached information is subject to further review and editing.

EXECUTIVE SUMMARY

Since its inception, the National Transportation Safety Board has been concerned about the evacuation of commercial airplanes in the event of an emergency. Several accidents investigated by the Safety Board in the last decade that involved emergency evacuations prompted the Safety Board to conduct a study on the evacuation of commercial airplanes.

Past research and studies on airplane evacuations have provided insight into specific factors, such as crewmember training and passenger behavior, that affect the outcome of evacuations; however, these studies had several limitations. First, in many of these studies, researchers did not examine successful evacuations; therefore, they were not always able to discuss what equipment and procedures worked well during evacuations. Second, only evacuations following serious accidents were examined and not evacuations arising from incidents. As a result, little is known about incident-related evacuations, which can provide insight into how successful evacuations can be performed and which can also identify safety deficiencies before serious accidents occur. Third, each study was a retrospective analysis of accident evacuations. This approach limited the researchers to information collected during the original investigation rather than collecting consistent information on a set of evacuations. Fourth, previous research on evacuations has not examined some of the most basic questions about how often commercial airplanes are evacuated, how many people are injured during evacuations, and how these injuries occur.

The Safety Board's study described in this report is the first prospective study of emergency evacuations of commercial airplanes. For the study, the Safety Board investigated 46 evacuations that occurred between September 1997 and June 1999 that involved 2,651 passengers. Eighteen different aircraft types were represented in this study. Based on information collected from the passengers, the flight attendants, the flight crews, the air carriers, and the aircraft rescue and firefighting units (ARFF), the Safety Board examined the following safety issues in the study:

• certification issues related to airplane evacuation;
• the effectiveness of evacuation equipment;
• the adequacy of air carrier and ARFF guidance and procedures related to evacuations; and
• communication issues related to evacuations.

As a result of this study, the National Transportation Safety Board adopted 20 safety recommendations and reiterated three to the Federal Aviation Administration.

CONCLUSIONS

1. On average, an evacuation for the study cases occurred every 11 days. An average of 336,328 departures occurred every 11 days in 1998 by scheduled aircraft operating under 14 Code of Federal Regulations Part 121.

2. In the 46 study cases, 92 percent (2,614) of the 2,846 occupants on board were uninjured, and 8 percent (232) were injured.

3. The Federal Aviation Administration does not evaluate the emergency evacuation capabilities of transport-category airplanes with fewer than 44 passenger seats or the emergency evacuation capabilities of air carriers operating commuter-category and transport-category airplanes with fewer than 44 passenger seats. In the interest of providing one level of safety, all passenger-carrying commercial airplanes and air carriers should be required to demonstrate emergency evacuation capabilities.

4. Adequate research has not been conducted to determine the appropriate exit row width on commercial airplanes.

5. In general, passengers in the Safety Board's study cases were able to access airplane exits without difficulty, except for the Little Rock, Arkansas, accident that occurred on June 1, 1999, in which interior cabin furnishings became dislodged and were obstacles to some passengers' access to exits.

6. Emergency lighting systems functioned as intended in the 30 evacuation cases investigated in detail.

7. In 43 of the 46 evacuation cases in the Safety Board's study, floor level exit doors were opened without difficulty.

8. Passengers continue to have problems opening overwing exits and stowing the hatch. The manner in which the exit is opened and the hatch is stowed is not intuitively obvious to passengers nor is it easily depicted graphically.

9. Most passengers seated in exit rows do not read the safety information provided to assist them in understanding the tasks they may need to perform in the event of an emergency evacuation, and they do not receive personal briefings from flight attendants even though personal briefings can aid passengers in their understanding of the tasks that they may be called upon to perform.

10. On some Fokker airplanes, flight attendants are seated too far from their assigned primary exit to provide immediate assistance to passengers who attempt to evacuate through the exit.

11. Overall, in 37 percent (7 of 19) of the evacuations with slide deployments in the Safety Board's study cases, there were problems with at least one slide. A slide problem in 37 percent of the evacuations in which slides were deployed is unacceptable for a safety system.

12. The majority of serious evacuation-related injuries in the Safety Board's study cases, excluding the Little Rock, Arkansas, accident, occurred at airplane door and overwing exits without slides.

13. Pilots are not receiving consistent guidance, particularly in flight operations and safety manuals, on when to evacuate an airplane.

14. Passengers benefit from precautionary safety briefings just prior to emergency occurrences.

15. Limiting exit use during evacuations in the Safety Board's study was not in accordance with the respective air carrier's existing evacuation procedures. At a minimum, all available floor level exits that are not blocked by a hazard should be used during an evacuation.

16. Evacuations involving slide use could be delayed if passengers sit at exits before boarding a slide or if crew commands do not direct passengers how to get onto a slide.

17. Without hands-on training specific to the airplane types that frequent their airports, aircraft rescue and firefighting personnel may be hindered in their ability to quickly and efficiently assist during evacuations.

18. Communication and coordination problems continue to exist between flight crews and flight attendants during airplane evacuations. Joint exercises for flight crews and flight attendants on evacuation have proven effective in resolving these problems.

19. Despite efforts and various techniques over the years to improve passenger attention to safety briefings, a large percentage of passengers continue to ignore preflight safety briefings. Also, despite guidance in the form of Federal Aviation Administration advisory circulars, many air carrier safety briefing cards do not clearly communicate safety information to passengers.

20. Passengers' efforts to evacuate an airplane with their carry-on baggage continue to pose a problem for flight attendants and are a serious risk to a successful evacuation of an airplane. Techniques on how to handle passengers who do not listen to flight attendants' instructions need to be addressed.

21. Unwarranted evacuations following Boeing 727 auxiliary power unit (APU) torching continue to exist despite past efforts by the Federal Aviation Administration to address this issue.

22. Evacuations continue to occur that are hampered by inefficient communication. Current evacuation communication would be significantly enhanced by the installation of independently powered evacuation alarms on all newly manufactured transport-category airplanes.

23. The frequency of false indications on the two regional airplanes in the Safety Board's study cases-the Saab 340 and the Canadair Regional Jet-is too high. There are insufficient data, however, to determine if the frequency of false smoke indications is peculiar to the two regional airplanes in the Safety Board's study or if the problem is more widespread.

24. Air carriers do not always make reports to the FAA SDR system, or reports are inadequate, to identify the extent of component problems or failures.

SAFETY RECOMMENDATIONS

As a result of this safety study, the National Transportation Safety Board made the following safety recommendations to the Federal Aviation Administration:

1.a Require all newly certificated commercial airplanes to meet the evacuation demonstration requirements prescribed in Title 14 Code of Federal Regulations Part 25, regardless of the number of passenger seats on the airplane.

1.b Require all commercial operators to meet the partial evacuation demonstration requirements prescribed in Title 14 Code of Federal Regulations Part 121, regardless of the number of passenger seats on the airplane.

2. Conduct additional research that examines the effects of different exit row widths, including 13 inches and 20 inches, on exit hatch removal and egress at Type III exits. The research should use an experimental design that reliably reflects actual evacuations through Type III (self help) exits on commercial airplanes.

3. Issue a final rule on exit row width at Type III (self help) exits based on the research described in Safety Recommendation (forthcoming).

4. Require Type III overwing (self help) exits on newly manufactured aircraft to be easy and intuitive to open and have automatic hatch stowage out of the egress path.

5. Require air carriers to provide all passengers seated in exit rows in which a qualified crewmember is not seated a preflight personal briefing on what to do in the event the exit may be needed.

6. Require flight attendants on Fokker 28 and Fokker 100 airplanes to be seated adjacent to their assigned primary exit. (This recommendation may be revised)

7. Review the 6-foot height requirement for exit assist means to determine if 6 feet continues to be the appropriate height below which an assist means is not needed. This review should include, at a minimum, an examination of injuries sustained during evacuations.

8. Require flight operations manuals and safety manuals to include on abnormal and emergency procedures checklists a checklist item that directs flight crews to initiate or consider emergency evacuation in all emergencies that could reasonably require an airplane evacuation (for example, cabin fire or engine fire).

9. Review air carriers' procedures to ensure that for those situations in which crews anticipate an eventual evacuation, adequate guidance is given both to pilots and flight attendants on providing passengers with precautionary safety briefings.

10. Review air carrier training programs to ensure that evacuation procedures call, at a minimum, for evacuation through all available floor level exits that are not blocked by a hazard.

11. Review air carrier procedures and training programs to ensure that the commands used for slide evacuations are consistent with the commands used for slide evacuations during certification.

12. Establish a task force to address the issue of providing periodic hands-on familiarization training, or the equivalent, for aircraft rescue and firefighting personnel at all 14 CFR Part 139 certified airports on each airplane type that serves the airport on a scheduled basis.

13. Require air carriers to conduct periodic joint evacuation exercises involving flight crews and flight attendants.

14. Conduct research and explore creative and effective methods that use state-of-the-art technology to convey safety information to passengers. The presented information should include a demonstration of all emergency evacuation procedures, such as how to open the emergency exits and exit the aircraft, including how to use the slides.

15. Require minimum comprehension testing for safety briefing cards.

16. Develop advisory material to address ways to minimize the problems associated with carry-on luggage during evacuations.

17. Require air carriers that operate Boeing 727s to include in the auxiliary power unit (APU) procedures instructions, when passengers are on board, that the flight crew will make a public address announcement about APU starts immediately prior to starting the APU. (This recommendation may be revised)

18. Require all newly manufactured transport-category airplanes operating under 14 Code of Federal Regulations Part 121 to be equipped with independently powered evacuation alarm systems operable from each crewmember station, and establish procedures and provide training to flight crews and flight attendants regarding the use of such systems.

19. Document the extent of false indications for cargo smoke detectors on all airplanes and improve the reliability of the detectors.

Also as a result of this safety study, the National Transportation Safety Board reiterates the following safety recommendations to the Federal Aviation Administration:

For a 12-month period, require that all operators of transport-category aircraft demonstrate the on-airplane operation of all emergency evacuation systems (including door opening assist mechanisms and slide or slide/raft deployment) on 10 percent of each type of airplane (minimum of one airplane per type) in their fleets. These demonstrations should be conducted on an airplane in a controlled environment so that the entire evacuation system can be properly evaluated by qualified personnel. The results of the demonstrations (including an explanation of the reasons for any failures) should be documented for each component of the system and should be reported to the FAA. (A-99-100)

Revise the requirements for evacuation system operational demonstrations and maintenance procedures in air carrier maintenance programs to improve the reliability of evacuation systems on the basis of an analysis of the demonstrations recommended in A-99-100. Participants in the analysis should include representatives from aircraft and slide manufacturers, airplane operators, and crewmember and maintenance associations. (A-99-101)

Modify the service difficulty reporting system so that it contains more complete and accurate information about component failures; for example, a) revise the various Service difficulty Report (SDR) forms and database to include cycles and times since last inspection for failed components; b) relate to the operators who submit SDRs the need for complete and accurate information when they report component failures; and c) remind Federal Aviation Administration inspectors assigned to Part 121 and Part 135 operators of their need to review the component failure reports for accuracy and completeness. (A-97-125)

NTSB