Chapter 3 RESEARCH AND TECHNOLOGIES FOR EVACUATION SYSTEMS CHAPTER 3 Research and Technologies for Evacuation Systems The aircraft evacuation system has three key In 1980, FAA’s Special Aviation Fire and elements: exits and slides, efficient means of Explosion Reduction (SAFER) Advisory reaching the exits, and the crew and passengers Committee published several recommendations who use them. To be able to leave one’s seat, to improve fire safety and survivability.2 FAA move toward an exit door or hatch, and escape used the committee’s recommendations to di- from the aircraft depends on the passenger’s rect its research and development (R&D) physical and mental condition, and tolerance to efforts, and produced new and modified regu- crash and fire hazards. These hazards, in turn, lations in a number of areas.3 The success of depend on the strength of seat attachments and FAA’s programs rests primarily on the devel- restraints, airframe energy absorption, and the opment of representative fire scenarios and test fire resistance of the cabin lining and seating methods. Currently, research is concentrated in materials. two categories: in-flight fires, where safety is measured by the ability to prevent, detect, and Evacuation performance thus requires en- contain a fire in the immediate vicinity of igni- hanced cabin safety to preclude incapacitation tion as well as discriminate from false alarms; from impact, smoke, heat, and toxic gases be- and postcrash fires, which in turn involve either fore egress can be achieved. Evacuation per- making the environment inhabitable for a formance also depends on the design and longer time or evacuating passengers more operation of emergency equipment and flight 4 quickly. The key programs relating to cabin attendant training. Cabin safety research and materials, emergency equipment, and training evacuation testing are essential elements of any are discussed below. effort to assess and improve evacuation safety. CABIN SAFETY RESEARCH AND Cabin Materials TECHNOLOGIES According to FAA, the most important recent The Federal Aviation Administration (FAA) improvement in cabin safety was the addition of researches and regulates several facets of cabin fire-blocking layers to seat cushions.5 FAA, safety for transport airplanes, rotorcraft, and with NIST participation, established in the mid- general aviation aircraft. The majority of the 1980s the methodology for determining the rate research and testing is accomplished at the at which hot gases are emitted from burning Technical Center and the Civil Aeromedical seat cushions. The fire blocking has been Institute (CAMI). FAA also relies on the shown to extend evacuation and survival time National Aeronautics and Space Administration by at least 40 seconds in one representative .“ and the National Institute of Standards and Technology (NIST) for contract or cooperative 2 Federal Aviation Administration, Find Repoti of the work in crashworthiness and fire safety, re- Special Aviation Fire and Explosion Reduction (SAFER) spectively. In passenger transport, after the Advisory Committee, vol. 1, Report FAA-ASF-80-4 ashington, DC: June 26, 1980). United States, the United Kingdom is the sec- !?’ ond largest contributor to cabin safety research R.G. Hill et al., “Aircraft Interior Panel Test Criteria Derived From Full-Scale Fire Tests, ” DOT/FAA/CT- and technology (R&T). Other foreign investiga- 85/23 (Atlantic City, NJ: Federal Aviation Administra- tors in fire safety research include Canada, tion Technical Center, Septemkw 1985), p. 1. Germany, the Nordic countries, Japan, and 4 Constintlne p. Sarkos, manager, Fire Safety Branch! Australia. 1 FAA Technical Center, personal communication, Apr. 22, 1992. 5 U.S. Depafiment of Transportation, Federal Aviation 1 Richard B~kowski, senior researcher, Building and Administration, Aircraft Safety Research Plan (Atlantic Fire Research Laboratory, Natioml Institute of Standards City, NJ: Federal Aviation Administration Technical and Technology, persoml communication, Apr. 8, 1992. Center, November 1991), p. 123. 27 28 . Aircraft Evacuation Testing: Research and Technology Issues postcrash fire scenario by delaying the onset of fire performance, and toxicology research to material ignition and reducing the spread of NIST. NIST conducts in-house research at the flames and toxic products of combustion.6 Building and Fire Research Laboratory and funds additional research through its University The FAA Technical Center developed the 11 Grants Program. According to NIST staff, standard test protocol for assessing cabin mate- recent gains in scientific knowledge and the rial flammability through comparison of labora- advent of measurement technology will shift tory studies and fill-scale fire testing (using a fire safety regulation toward performance stan- reconfigured C-133 fuselage). In simulated dards rather than design criteria. postcrash fires, evaluation of combustion gas and temperature profiles indicated that the oc- The measurement technology required for currence of cabin flashover7 dictated surviv- quantitatively assessing evacuation system per- ability, and that flashover can be best formance, including human factors, has not characterized by heat release levels.8 This been developed to the same degree. The Avia- prompted the development of the current heat tion Rulemaking Advisory Committee efforts to release standard instead of limits on specific replace evacuation design criteria with per- combustion products.9 Today FAA continues to formance standards suffer from the lack of investigate fire behavior, smoke toxicity, the sophisticated analytic tools and human per- behavior of composite materials, and the effec- formance data. tiveness of potential safety improvements using the FAA Technical Center’s DC-10 and B-707 10 Emergency Equipment test craft. Analysis of the 1985 Manchester aborted CAMI has extensively studied the effects of takeoff and subsequent fuel-fed fire prompted fire on aircraft interiors, supporting rulemaking several recommended design changes, includ- for crew member protective breathing equip- ing improved access to overwing exits and ment (PBE). Continuing fire safety research cabin interior hardening, most of which have topics include smoke release and relative toxic- been implemented.12 The accident also renewed ity of materials used in cabin finishings, and interest in cabin water sprays and passenger methods to improve evacuation under toxic protective breathing equipment. The relative smoke conditions. merits and disadvantages of these proposals are discussed below, along with the topic of Over the years, FAA’s Technical Center risk/risk assessment. contracted out portions of its materials safety, Protective Breathing Equipment 6 Job J, Petrakis, “FAA Occupant Protection and Time and the thermo-toxic environment are Cabin Safety Overview, ” in Proceedings of the Flight two critical aspects of survival in aircraft acci- Safety FoundationlFederal Aviation Administration 13 International Aircrt@ Occupant Sa$ety Conference and dents involving fire. Based on R&D done at Workshop, DOTIFAAIOV-89-2 (Washington, DC: U.S. CAMI, criteria for PBE for air transport crew Department of Transportation, August 1989), p. 43. 7 F]ashov~r is the sudden, rapid, and uncontrolled growth of fire throughout the cabin, generating high tem- peratures and toxic gases and robbing the cabin atmos- 11 Bukowski, op. cit., fOOtnOte 1. here of oxygen. 12 Arthur Reed, “Technology Safety . For Cabin-Fire ! Constantine P. Sarkos, manager, Fire Safety Branch, Survival, ” Air Transport Worki, October 1991, pp. 101- FAA Technical Center, personal communication, Jan. 15, 106. 1993. 13 Garnet A. Ivfch et al., Civil Aeromedical Author- 9 Also known as the 65/65 rule, which refers to the ity, l%e Eflects of Wearing Passenger Protective Breath- maximum allowable rate of heat release, in kW/m2, and ing Equipment on Evacuation Times Through Type III and the total heat reiease, in kW-min/m2, under specified test Type IV Emergency Aircraft fiits in Clear Air and Smoke, criteria. Final Repoti, DOT/FAA/AM-89/12 (Washington, DC: 10 Alan S. Brown, “Fire Rule Changes Aircraft Mate- U.S. Department of Transportation, November 1989), p. rials Mix, ” Aerospace America, March 1991, pp. 20-24. 1 Chapter 3—Research and Technologies for Evacuation Systems . 29 members were issued in June 1983.14 Consist- spent donning smokehoods during the period ing of a full-face oxygen mask or combination when conditions permit the fastest egress re- smoke goggles and oxygen mask, crew member duces their potential to save lives and may even PBE is required equipment for all aircraft op- result in more deaths. 18 erating under 14 CFR 121. Water Spray Although the investigation of the Manchester FAA commissioned an early cost/benefit accident resulted in a recommendation for pro- study of fire management systems and safety vision of passenger PBE, or smokehoods, rules improvements, completed in 1983. CAA re- mandating their installation on transport aircraft 15 viewed worldwide accidents involving fire-re- have not been issued. Two general types of lated deaths over the 1966 to 1985 period, and smokehoods, filter and oxygen-generating, concluded that the benefit attributable to having have been proposed. The lightweight filter type an onboard cabin fire suppression capability is susceptible to carbon monoxide contamina- (e.g., a water spray system) is likely to be sub- tion and becomes ineffective when cabin oxy- stantial and exceeds the benefit attributable