Safety Recommendation A-00-072

The Safety Board notes that at the October 3, 2003, meeting, the FAA stated that it disagrees with this recommendation, is moving away from requiring full-scale evacuation demonstrations, and does not support extending this requirement to airplanes with fewer than 44 seats, that are certified under Part 25. The FAA stated that it is concerned about potential injuries to participants during these tests. In addition, the Board notes the FAA's belief that there is appreciably more evacuation capacity than needed to pass the 90-second evacuation time requirement based on the number and ratings of the exits in airplanes with fewer than 44 seats.

The FAA recently provided the Safety Board with information supporting its conclusion that these aircraft have appreciably more evacuation capacity than necessary based on the number and ratings of the exits. The FAA noted that any airplane with more than 20 seats is required to have at least 2 pairs of exits, at least one of which can be a type II exit, while the other can be as small as a type III. The FAA indicated that research and empirical data from certification tests show that a type II exit has a flow rate of 45 people per minute while a type III has a flow rate between 33 and 38 people per minute.

This results in a total cabin evacuation time for 44 passengers plus a crew of 3 of approximately 38 seconds, well below the 90-second limit. Therefore, based on the threat of injuries to test subjects during evacuation demonstration tests and the significant difference between the exit capacity and the passenger cabin size, the FAA does not plan to take the recommended action.

The Safety Board disagrees with the FAA. The 90-second evacuation test is a systems-performance requirement that evaluates factors other than simply the flow capacities of the exits, such as passenger hesitation at the exit (particularly important in aircraft with fewer than 44 seats-many of which have an exit sill height less than 6 feet above the ground), the width and configuration of aisles inside the cabin, and crew procedures for preparing the cabin and encouraging passengers to evacuate. The Board notes that the exit flow rates that the FAA used in its analysis are based on tests in which subjects evacuated onto a slide or onto a platform that was level with the exit.

In contrast, in many aircraft having fewer than 44 seats, the exit is located as much as 6 feet above the ground, likely resulting in much slower exit flow rates. As part of its investigation of a runway collision accident in Quincy, Illinois, on November 19, 1996, the Board learned that a full-scale evacuation demonstration, requiring more than 80 seconds to complete, had been conducted as part of the certification under Part 23 for the Beech 1900 aircraft.

The Board is also aware of other aircraft with seating capacities near 44 seats that had evacuation demonstration times of greater than 80 seconds, bringing into question the margin of excess capacity in the evacuation test conditions to which the FAA refers. On this basis, the Board believes that the FAA's conclusion about the excess capacity is not supported by the limited data available.

The FAA supplied information to the Safety Board on injuries to participants during evacuation demonstration tests performed for aircraft with more than 44 seats. Further, the Board believes that the injuries to participants may illustrate deficiencies in an evacuation system that need to be addressed before an airplane enters service. Although we share the FAA's concern about injuries to test subjects, the Board does not believe this concern should be a basis for moving away from requiring an evacuation demonstration test for newly certificated aircraft; rather, the Board believes that the FAA should develop methods to reduce injuries during these tests.

We appreciate the FAA's providing (1) the basis for its belief that the excess exit capacity obviates the need for an evacuation demonstration test and (2) the information on injuries to test subjects during evacuation demonstration tests. However, the Board continues to believe that an evacuation demonstration test for aircraft with fewer than 44 seats is needed. Therefore, Safety Recommendation A-00-72 is classified "Closed--Unacceptable Action."

ACTIONS FOR CLOUSURE BASED ON MEETING WITH THE NTSB- · FAA will share information on injuries to subject during evacuation demonstrations, · FAA will also send CAMI references and data on door flow rate data, Rational discussed during meeting and flow rate data references: · Airplanes with more than 20 seats require at least two pairs of exits (4 exits total). · An airplane with 44 pax- ane pair would have to be at least as large as a type II exit. The second pair could be as small as a type ill exit. · The evacuation demonstration requirements are such that "Not more than 50% of the exits. I, may be used".

Therefore, one exit of each pair is used, and in the worst case scenario, includes one type II and one type III exit. · Exit flow rates established via empirical data from Certification and Research and Development testing o Type III -approximately 33-38 persons per minute o Type II -at approximately 45 persons per minute. · Therefore, 44 passengers plus crew could be evacuated at those rates in well under one minute, even allowing for preparation time · Extending the requirement would increase the potential for injuries to the participants In addition, there are numerous data available regarding the rate at which type IIIl exits flow.

The FAA has documented type III performance in DOT/FAA/AM-OZll6, DOTIFAAIAM-99170, DOT/FAA/AM-95/22, DOT/FAA/AM-95125 among others., The link to the CAMI website is http://www.cami.jccbi.gov/AAM-400A/Abstracts/2000TechRep.htm These reports show an overall evacuation rate of around 37.5 persons/minute, although there are individual tests that are faster, and some that are slower. With regard to Type II exits, there are not as extensive data available, and primarily only certification data. The type II exit on the Boeing 707 for example, performed at 47.5 persons/minute.

The Aerospace Industries Association Crashworthiness Development Program reports document that the performance of Type II exits is approximately the same as that of type I exits, when both have slides. However. even if the performance of the type II exit is assumed to be no better than the type Ill exit, the airplane would have an evacuation capability of 75 persons/minute (37.5X2), At that rate, 44 passengers plus 3 crewmembers can be evacuated in around 38 seconds, Allowing ten seconds for exit preparation time there is a margin of around 42 seconds left below the 90 second limit.

The Safety Board acknowledges that regulations regarding the number of exits may result in a wide safety margin, but notes that these regulations will simply ensure the aircraft will likely pass the evacuation demonstration requirement. Although all aircraft must have sufficient exit capacity for their passenger loads, they sometimes do not pass the evacuation demonstration requirement, which indicates that relying on exit capacity alone is not sufficient to determine the maximum passenger load that an aircraft can safely carry and evacuate in an emergency.

The Board notes that airplanes certificated under Part 23, which often have fewer than 44 seats, require an evacuation demonstration even though Part 25 airplanes with fewer than 44 seats are not so required. The Board learned, as part of the investigation of a runway collision accident in Quincy, Illinois, involving a Beech 1900 aircraft on November 19, 1996, that a full-scale evacuation demonstration was conducted as part of the certification for the Beech 1900 under Part 23. It took more than 80 seconds to complete this full-scale evacuation demonstration on the Beech 1900.

The Board is aware of other aircraft with seating capacities around or fewer than 44 seats that had evacuation demonstration times greater than 80 seconds, bringing into question the large margin of excess capacity to which the FAA refers. The Board is also concerned that there is no requirement to demonstrate that cockpit crews of aircraft with fewer than 20 seats without a flight attendant can quickly open cabin exits in addition to their duties as flight crewmembers.

In its recommendation letter, the Safety Board expressed concern that existing regulations that exempt certain airplanes and operations because of passenger seating capacity are not consistent with the goal of providing "one level of safety" for all passenger-carrying commercial airplanes. The Safety Board disagrees with the FAA's belief that aircraft below some passenger capacity does not require full-scale or partial evacuation demonstration and asks the FAA to reconsider that position. Pending completion of the recommended actions, Safety Recommendation A-00-72 and A-00-73 are classified

Letter Mail Controlled 11/14/2000 4:39:44 PM MC# 2001688 The requirement for full-scale demonstration was added to the regulations (initially as an operating requirement and later as a type certification requirement). Full-scale demonstrations were added because a final proof-of-concept test was considered necessary to ensure that the entire system would perform as intended and to ensure that evacuation capability would be consistent across airplane types. The requirement for evacuation demonstrations was not part of the type certification requirements until 1967 when it was added to 14 CFR Part 25 by Amendment 25-15.

The type design rule has always contained an exclusion for airplanes with 44 or fewer passengers. The requirement for an evacuation demonstration is one of many requirements relating to overall evacuation capability. Other requirements include the size of the exit, the type and number of exits, the interior arrangement limitations on the aisle, the dimensions of cross-aisle and passageway, the design of the escape system, and emergency lighting and exit marking. Each of these over 20 detailed requirements in 14 CFR Part 25 address particular aspects of the overall evacuation capability of the airplane, not only in a demonstration, but also in real-world conditions.

Each regulation must be complied with individually and independent of the other requirements. The number of passengers permitted on a transport-category airplane (14 CFR Part 25) is limited, first and foremost by the type and number of emergency exits installed. The type and number of exits establish the maximum number of passengers that can be carried, regardless of any evacuation demonstration. In other words, the results of the demonstration cannot be used to justify an increase to the passenger capacity above that permitted by the exit complement. The full-scale demonstrations can only confirm the passenger capacity or result in a reduction of that capacity if warranted.