Improvements to Aircraft Survivability

Tuesday, February 4, 2020

Over the years, the FAA has conducted extensive research and significantly upgraded cabin safety requirements to increase the likelihood of passenger survivability in aviation accidents. Many aviation accidents are survivable, and improvements to cabin safety and the prevention and control of in-flight fires have contributed to passenger survivability.

FAA cabin research is conducted at the William J. Hughes Technical Center in Atlantic City, N.J. and the Mike Monroney Aeronautical Center in Oklahoma City.

The following are examples of advancements in cabin safety.  The times noted with respect to the specific advancements are not cumulative and depend on the conditions of evacuation.

  • Improved seat cushions with reduced flammability: An October 1984 FAA rule required that cushions installed on passenger and flight attendant seats comply with a significantly more stringent flammability test standard using a two gallon per hour kerosene burner. The rule applied to all new transport airplane certification programs. The rule also applied to currently certificated airplane models for airplanes manufactured after November 1987. Air carriers replaced 650,000 foam seat cushions on the U.S. fleet. The FAA found that the new material did a better job retarding burning and provided 40 to 60 seconds of additional time for aircraft evacuation when compared to the time available when seats without the improved cushions were installed under the test/research conditions. All existing seats in the U.S. fleet meet the improved standards. The international aviation community adopted the same standards.

  • Floor proximity emergency escape path marking: By 1986, the U.S. commercial fleet was retrofitted with floor proximity lighting, marking the completion of a two-year compliance schedule. Since smoke rises and can obscure overhead lighting, the FAA determined that floor lighting could improve the evacuation rate by 20 percent under conditions when there is significant smoke in the cabin. The floor proximity marking system aids passengers by marking evacuation paths and identifying exits utilizing illumination sources located close to the floor.

  • Lavatory smoke detectors: In 1986, the FAA required air carriers to install smoke detectors in lavatories. Air carriers were given 18 months to complete the installation.

  • Lavatory fire extinguishers: In 1987, the FAA required air carriers to install automatic fire extinguishers in the waste paper bin in all aircraft lavatories. Air carriers had two years to comply.

  • Halon fire extinguishers: In 1986, portable Halon fire extinguishers were added to all commercial aircraft, following a 12-month compliance time. The FAA requires two Halon fire extinguishers per aircraft, in addition to other required fire extinguishers.

  • Improved interior materials: In 1985, the FAA developed a new test standard for large surface area panels used in the construction of ceilings, walls, galleys, overhead bins, and partitions. The intent of the new standard was to delay the onset of a cabin flash fire or flashover event, giving passengers and crews more time to evacuate the airplane after an accident. The agency required that all commercial aircraft produced after August 1988 have panels that met an intermediate level of heat release and after August 1990, met the final level of reduced heat release. In 1988, the FAA further required that the materials in the panels noted above also comply with a smoke emissions test standard. Although there was no retrofit of the existing fleet, the FAA required that these improved materials be used during major cabin refurbishment. This improvement in cabin material flammability has been demonstrated to delay flashover in the cabin when compared to materials that do not comply with the improved standards. Flashover is the point in time, during a fire, when conditions are generally considered to no longer support life. The amount of additional evacuation time will vary in actual accidents depending on the severity and extent of the fire. In August 2012, the FAA streamlined the flammability testing of many commonly used interior materials.

  • Cargo compartment liners: In 1986, the FAA issued a new test standard using the two gallon per hour kerosene burner to improve fire safety in Class C and D cargo and baggage compartments. The rule established burn-through resistance fire test criteria for compartment ceiling and wall liners. The existing fleet was required to meet the new standard or two other design standards. This rule change significantly improved the flammability properties of the lining material and has been proven to delay fire in a cargo compartment from breaching the confines of the compartment. Maintaining the integrity of the Class C compartment liner allows the required extinguishing agent more time to extinguish the fire. Subsequent to this rulemaking, Class D cargo compartments were effectively banned from installation in passenger carrying airplanes.

  • Cargo compartment fire detection/suppression: In 1998, the FAA required that all large passenger aircraft have fire detection and suppression systems installed in all cargo compartments by March 2001. This rule affected aircraft in-service at the time of rule issuance and all aircraft manufactured after that date.

    In 2016, the FAA issued new standards for cargo compartments that raised the level of safety for certain cargo compartment configurations eliminating the need for a person to enter a cargo compartment to fight a fire. The new standards limited the size of Class B cargo compartments for future airplanes and airplane modifications in order to make it possible to fight a fire in the compartment without entering the compartment. The new standards also created a new Class F cargo compartment classification from previous larger Class B compartments with more stringent criteria for firefighting capability that may include a manually activated fire suppression system.

  • Thermal/acoustic insulation: In May 2000, the agency required that operators of more than 600 aircraft replace insulation blankets covered with metalized polyethylene terephthalate within four years. Replacement materials had to meet a new flame propagation standard that had been developed in 1999. During the same time period, the FAA also developed another test standard to be used for improving the resistance of the insulation to burn-through from an external fire. In 2003, the FAA adopted both test standards into the requirements for new certificated airplane models. The rule also required that previously certificated but newly manufactured airplanes entering the U.S. fleet had to comply as well. The flame propagation requirements went into effect in September 2005. The burn-through requirements went into effect in September 2007 but were later extended to September 2009.

  • 16g seats: In 1988, the FAA issued regulations requiring that all newly developed transport aircraft use “16g” seats. Using a test dummy, these seats undergo dynamic testing and evaluation regarding injury protection. Similar to automobile crash tests, the FAA tests are designed specifically for the aviation environment. Previously, seats were designed and approved to a static 9g standard with no occupant injury criteria. Later rulemaking, effective October 2005, required that transport category airplanes in part 121 operations, manufactured on or after October 2009, must comply with the 16g dynamic standard. In 2010, the agency published guidance on the importance of analyzing how interior structures, such as seats, interact with other structures due to critical loads. In July 2012, the FAA issued criteria for side-facing seats that are equivalent to the occupant protection for standard forward-facing seats. In 2016, the FAA issued criteria to address seats oriented at arbitrary angles, to similarly provide occupant protection equivalent to standard forward-facing seats for future airplanes and airplane modifications.

  • Improved access to Type III exits: In 1994, the FAA improved the access to Type III exits, by specifying minimum standards for the passageway from the aisle to the exit for airplanes with 60 or more passengers. Type III exits are the non-floor level exit typically located over the wing in thousands of airplanes in air carrier service, like Boeing 737 and Airbus A320 airplanes. Egress rates through the exits were found to be approximately 14 percent faster than through previous narrower passageways.