Crash Survivability

Abstract

The United States aviation system continues to grow at an alarming rate but despite this growth the system continues to maintain a high level of safety. A tremendous amount of research was conducted during a 16 year period between 1983 and 2000 in regards to post impact fires and its significant contribution to injuries and fatalities in accidents. A majority of these accidents are believed to of been potentially survivable. Research has revealed the importance of examining occupant survivability as it has the potential to yield a reduction in accident rates and reverse the negative perception that air carrier accidents are not survivable. New technologies in the engineering of a new post impact fire resistant fuel system has the potential to prevent a fire from occurring during aircraft impact.

Post Impact Fire Survivability

On June 1, 1999, American Airlines flight 1420, crashed during the landing evolution after it overran the end of runway at Little Rock National Airport in Little Rock, Arkansas. The flight departed at approximately 2300 from Dallas/Fort Worth International Airport, Texas. The flight had a total of 145 people which consisted of 2 flight crewmembers, 4 flight attendants, and 139 passengers aboard. During the landing evolution the aircraft ran past the end of the runway and struck multiple tubes that were extended from the instrument landing system which was located approximately 411 feet past the end of the runway. The aircraft crashed through a chain link security fence and skid down a rock embankment into a large flood plain which was located approximately 15 feet below the main runway elevation. The aircraft them collided with a supporting structure of the runway approach lighting system. The collision caused an aircraft fire which claimed the lives of the captain and 10 passengers. The first officer, the flight attendants and 105 passengers suffered from minor to serious injuries and a total of 24 passengers were not injured. The aircraft was ultimately destroyed by impact forces and the post impact fire.

Primary Findings

During the investigation it was discovered that the Flight 1420 was the third and final leg for the flight crew. Before the flight the flight crew received trip paperwork which included an American Airlines weather advisory indicating thunderstorms along the planned route and two National Weather Service (NWS) in-flight weather advisories for an area of severe thunderstorms along the planned route (FAA, 2013). The aircraft was initially intended to be used for the flight but it was delayed in its arrival to Dallas/Fort Worth because of the adverse weather in the area (FAA. 2013). After 9 p.m., the first officer notified gate agents that the flight would need to depart no later than 2316 because of the American's company duty time limitation. The first officer then telephoned the flight dispatcher to suggest that either another airplane be obtained for the flight or to cancel the flight. The cockpit voice recorder (CVR) indicated that the flight crew had discussed the weather and the need to expedite the approach.

The investigation determined that the probable cause of the accident was the flight crew's failure to discontinue the approach when severe thunderstorms and their associated hazards to flight operations had moved into the airport area and the crew's failure to ensure that the spoilers had extended after touchdown (FAA, 2013). Another contributing factor to the accident was the flight crew's impaired performance resulting from fatigue and the situational stress associated with the intent to land under the circumstances (FAA, 2013). Additionally, continuation of the approach to a landing when the company's maximum crosswind component was exceeded, and the use of reverse thrust greater than 1.3 engine pressure ratio after landing (FAA, 2013).

Conclusions

This investigation was just one of the accidents that was investigated during a 16 year period between 1983 and 2000 in regards to post impact fires and its significant contribution to injuries and fatalities in accidents. The data collected and the history of post impact fires help investigators become informed in an effort to provide discussion material with the intent of