Fly the fiery skies: long after ValuJet, many planes still don't have smoke detectors or fire extinguishers in their cargo holds.
The Hole in the Theory
Fire detectors and pressurized bottles of Halon -- a highly effective fire fighting agent -- have long been used in the cargo holds of larger jets like the Boeing 777 and the Lockheed L-1011. But for years the airline industry has argued that the smaller cargo holds on smaller planes could contain any fire with their insulating blankets and nearly airtight construction. In theory, flames would be snuffed out through oxygen starvation, rendering fire detectors and Halon extinguishers unnecessary.
But the theory ignores the fact that the holds of these smaller jets, like the popular Boeing 737, are increasingly packed with hazardous cargo that render the "fire-prevention-through-oxygen-starvation" strategy grossly inadequate. The ValuJet disaster was the first case to bring this problem to the public's attention. That crash was apparently caused when the oxygen from a load of mislabeled canisters placed in the plane's cargo hold fanned an electrical fire into a fatal white-hot conflagration. The airtight construction theory had not accounted for the addition of more oxygen from the canisters. Of course, even if there had been Halon bottles in the plane's hold, the 110 people aboard flight 592 might not have been saved; the flow of oxygen that the canisters were adding to the fire probably would have overwhelmed the limited supply of Halon: However, a smoke detector in the hold of flight 592 could have made a difference. As it was, the crew didn't know the plane was on fire until smoke began filling the cockpit. Had they been alerted earlier they could have returned to Miami sooner or, if the fire had started while the plane was still on the ground, not taken off in the first place. Skeptics need only consider the fortuitous experience of the detector-equipped Federal Express DC-10 cargo jetliner that caught fire at 33,000 feet on September 5, 1996. Its detection system immediately alerted the crew, which made an emergency landing four minutes later -- allowing all five crew members to escape before the aircraft was consumed by fire.
Since the ValuJet disaster, the government has endeavored to reassure the travelling public of the safety of air travel by banning the transport of oxygen-generating canisters aboard passenger jets. But don't loosen your grip on that armrest yet. Oxygen canisters are only one of the many hazardous items routinely stored in aircraft cargo holds. Consider the grooming products packed in passengers' bags. Since the banning of the chlorofluorocarbons once used as propellants in the aerosol cans that dispense anything from shaving cream to deodorant, manufacturers have switched to natural gases like butane and propane. In the event of an in-flight fire in the cargo bay, these natural gases pose a serious danger. The pressure inside, say, a can of hair spray will build as the heat increases in the compartment, causing the can to cook off with explosive force. It won't necessarily punch through the side walls of the cargo compartment, but the can could strike the underneath of the passenger deck with enough force to strip threads on screws and cause the floor to buckle upward. The damage effectively opens a breach in the compartment's containment wall, allowing additional oxygen from the passenger cabin to flow into the cargo hold. Meanwhile, the propane released by the bursting can adds more fuel to the conflagration, compromising the whole "oxygen suppressing" design philosophy for smaller cargo holds.
As more people become aware of the threat posed by hazardous cargo, the call for fire extinguishing equipment on all airplanes with smaller cargo holds will get louder. Jim Jensen, ValuJet's vice president for maintenance and engineering, estimates that his company's airliners could be equipped with detectors and extinguishers at a cost of $70,000 to $100,000 per plane. In fact, his airline has been flying a DC-9 (in non-revenue service) equipped with a prototype detector, approved by the FAA on an experimental basis, to establish the detector's reliability and to test its susceptibility to false alarms. Delta Air Lines, too, has moved out with a design already flight-tested and FAA-certified, and the equipment already is being installed in the first of the carrier's 60-plus Boeing 737s.
Delta and ValuJet are notable exceptions in an industry where most carriers seem to be waiting for orders. In a May 13 letter to Carol Hallett, president of the Air Transport Association, the airline industry's most powerful lobby group, National Transportation Safety Board Chairman Jim Hall wrote, "I urge your members to follow through on the commitment they made six months ago to retrofit their Class D cargo compartments." Hallet responded with a strongly-worded reply challenging Hall's technical competence and declaring that the task of equipping airliners with smoke detectors is being "expeditiously accomplished." Yet the time line she provided Hall showed that her member airlines plan to take five years to complete the job. In an attempt to justify this schedule, Hallett noted that the systems for each aircraft type must be certified so that they "do not compromise the safety of the basic aircraft design? Hallett countered, with some justification, "It is neither prudent for public safety ... nor the industry ... for airline mechanics to simply begin, opening up aircraft, drilling holes, stringing wire and hanging view equipment without an engineering plan and required FAA approvals."
She's right, but the speedy progress of Delta and ValuJet, which fully involved the FAA, shows what can be done safely and expeditiously. It doesn't need to take another five years to install equipment that would give aircrews an extra five minutes warning to save themselves and their passengers.
David Evans is a retired Marine Corps lieutenant colonel. He is presently managing editor of the Aviation Group at Phillips Business Information Inc. in Potomac, Md.
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|Title Annotation:||ValuJet Airlines Inc.|
|Date:||Sep 1, 1997|
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