RFT 604: Airliner Cargo Fire Systems
On the afternoon of May 11, 1996, Valet Flight 592 pushed back from gate G2 in Miami after a delay of 1 hour and 4 minutes due to mechanical problems.There were 110 people on board: 105 passengers, mainly from Florida and Georgia, and a crew of two pilots and three flight attendants. At 2:04 PM EDT, the DC-9 took off from runway 9L (now runway 8R) and began a normal climb. At 2:10 p.m the passengers started to smell smoke. At the same time, the pilots heard a loud bang in their headsets and noticed the plane was losing electrical power. The sag in electrical power and the bang were eventually determined to be the result of a tire in the cargo hold exploding. Seconds later, a flight attendant entered the cockpit and informed the flight crew of a fire in the passenger cabin. Passengers' shouts of "fire, fire, fire" were recorded on the cockpit voice recorder (CVR) when the cockpit door was opened. Though ValuJet's flight attendant training manual stated that the cockpit door should not be opened when smoke or other harmful gases might be present in the cabin, the intercom was not functional and informing the pilots of what was happening was difficult. The flight data recorder (FDR) indicated a progressive failure of the DC-9's electrical and flight control systems due to the spreading fire. Kubeck and Hazen immediately asked air traffic control for a return to Miami due to the increasing smoke in the cockpit and cabin, and were given instructions for a return to the airport. One minute later, Hazen requested the nearest available airport. Kubeck began to turn the plane left in preparation for the return to Miami. Flight 592 disappeared from radar at 2:13:42 PM, the exact time that it crashed. Eyewitnesses nearby watched as the plane banked sharply, rolled onto its side and nosedived into the Francis S. Taylor Wildlife Management Area in the Everglades, a few miles west of Miami, at a speed in excess of 507 miles per hour (441 kn; 816 km/h). Kubeck lost control of the plane less than 10 seconds before impact. Examination of debris suggested that the fire had burned through the floorboards in the cabin, resulting in structural failure and damage to cables underneath the instrument panels. The NTSB report on the accident stated, "the Safety Board cannot rule out the possibility that the flightcrew was incapacitated by smoke or heat in the cockpit during the last 7 seconds of the flight." At the end of a fifteen-month investigation, the National Transportation Safety Board (NTSB) determined that the fire that downed Flight 592 developed in a cargo compartment below the passenger cabin. The cargo compartment was a Class D design, in which fire suppression is accomplished by sealing off the hold from outside air. Any fire in such an airtight compartment would quickly exhaust all available oxidizers and then burn itself out. As the fire suppression can be accomplished without any intervention by the crew, such holds are not equipped with smoke detectors. However, the NTSB quickly determined that just before takeoff, 144 expired chemical oxygen generators, each slightly larger than the size of a tennis ball can, had been placed in the cargo compartment in five boxes marked COMAT (company material) by ValuJet's maintenance contractor, SabreTech, in violation of Federal Aviation Administration (FAA) regulations forbidding the transport of hazardous materials in passenger aircraft cargo holds.[a] Failure to cover the generators' firing pins with the prescribed plastic caps made an accidental activation much more likely. The investigation revealed that rather than covering them, the cords attached to the firing pins were simply cut or duct-taped around the cans, and Scotch tape was also used to stick the ends down. SabreTech employees indicated on the cargo manifest that the "oxy canisters", which were loosely packed in the boxes that were each sealed with tape and bubble wrap, were "empty". ValuJet workers
