The National Transportation Safety Board, in concluding its investigation today of the May 1996 ValuJet crash into the Everglades -- which took the lives of all 110 persons aboard – has cited the airline, the airline's contract maintenance company and the federal regulatory agency whose actions were causal to the crash.
On May 11, 1996, ValuJet flight 592, a DC-9, registration number N904VJ, crashed into the Florida Everglades about 10 minutes after takeoff from Miami International Airport on a flight to Atlanta, Georgia. All 105 passengers and 5 crew died in the accident. In the minutes before the crash, the flightcrew reported to air traffic controllers that they were attempting to return to Miami because of smoke in the cabin.
Evidence from the wreckage recovery showed that there was an intense in-flight fire in the forward cargo compartment, which contained, among other things, more than 100 expired, but still active, chemical oxygen generators and three aircraft tires being carried as company material. The Board determined that, sometime between when those materials were loaded on the aircraft and when the aircraft took off, one or more of the oxygen generators activated, initiating a fire that eventually brought the aircraft down.
The forward cargo compartment was a so-called "Class D" compartment. That is, it has a restricted airflow design that theoretically cannot sustain a fire; once the oxygen in the compartment has been consumed by a fire, the fire will die out. This design philosophy did not take into account the possibility of an oxydizer being placed in the compartment that could sustain a fire for a prolonged period of time. Class D compartments are not required to have smoke detector or fire suppression systems in them. It appeared from the cockpit voice recorder that the first indication the flight crew had of a fire aboard ValuJet flight 592 was shouts of "fire" from the passenger cabin.
As hazardous materials, those generators should not have been loaded onto the aircraft (ValuJet was not permitted to carry hazardous materials). In addition, the Board determined that the generators were not properly protected from inadvertent actuation by the installation of safety caps.
The Board determined that the accident was caused by: (1) the failure of SabreTech (a contract maintenance operation in Miami) to properly prepare, package, and identify unexpended chemical oxygen generators before presenting them to ValuJet for transportation; (2) the failure of ValuJet to properly oversee its contract maintenance program to ensure compliance with maintenance, maintenance training, and hazardous materials requirements and practices; and (3) the failure of the Federal Aviation Administration to require smoke detection and fire suppression systems in Class D cargo compartments.
Contributing to the accident, the Board found, was the failure of the FAA to adequately monitor ValuJet's heavy maintenance program and responsibilities, including ValuJet's oversight of its contractors, and SabreTech's repair station certificate; the failure of the FAA to adequately respond to earlier chemical oxygen generator fires with programs to address the potential hazards they posed (the Board cited 6 cases in the 10 years before the ValuJet accident involving fires caused by oxygen generators); and the failure of ValuJet to ensure that both ValuJet and contract maintenance employees were aware of the airline's "no-carry" hazardous materials policy and had received appropriate hazardous materials training.
The expired oxygen generators had been removed from three ValuJet MD-80 aircraft undergoing maintenance at SabreTech. The Board's investigation revealed that, although many of the SabreTech mechanics who removed the generators understood the danger they could pose, the generators were nevertheless delivered to SabreTech's shipping and receiving department without communicating what the items were, or that they were hazardous. Rather than dispose of the generators properly or at least fit them with safety caps designed to prevent their accidental activation, they were boxed up and sent to ValuJet in order to clean up the maintenance area in preparation for a visit by a prospective customer. In addition, they were incorrectly labeled "Oxy Generators - Empty."
The Safety Board concluded that the lack of a formal system in SabreTech's shipping and receiving department, including procedures for tracking the handling and disposition of hazardous materials, contributed to the improper transportation of the generators aboard flight 592.
ValuJet, for its part, did not oversee SabreTech adequately, the Board said. Had it ensured that SabreTech's employees were trained on the company's lack of authority to transport hazardous materials and had received hazardous materials recognition training, SabreTech might not have mishandled the packaging and shipment of the oxygen generators.
The Board also cited the FAA's failure to require smoke detection and fire suppression systems in Class D cargo holds, despite recommendations the NTSB issued in 1988, following a fire in the cargo hold of an American Airlines DC-9 in Nashville, Tennessee. Because of the FAA's continued assertions that retrofitting the more than 2,500 airliners in the U.S. that had such cargo compartments would not be justified on a cost/benefit basis, those recommendations were closed "Unacceptable Action" by the Board in 1993.
In its final report today, the Board concluded, "Had the FAA required fire/smoke detection and and/or fire extinguishment systems in Class D cargo compartments, as the Safety Board recommended in 1988, ValuJet flight 592 would likely not have crashed."
Earlier this year, the FAA proposed a rule that would require smoke detection and fire suppression systems in these cargo compartments within a 3-year period, once the rule is made final. Among the 22 recommendations the Board sent to the FAA in today's report was that the FAA expedite final rulemaking on this issue.
Other recommendations to the FAA called for requiring that the cockpit-cabin portion of airliner interphone systems be operative for every flight; establishing performance standards for the rapid donning of smoke goggles by flight crews; requiring manufacturers to affix warning labels on chemical oxygen generators; enhancing the FAA's oversight techniques to more effectively identify and address improper maintenance activities; reviewing the issue of personnel fatigue in aviation maintenance; and ensuring that all Part 121 airlines' maintenance functions receive the same level of FAA surveillance, whether they be in-house or contract operations.
Other recommendations were issued to the Research and Special Programs Administration, the U.S. Postal Service and the Air Transport Association.
The NTSB's complete report, PB97-910406, may be purchased from the National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161, (703) 487-4650.