A MOHAWK Airlines turbojet, stricken by engine trouble and struggling to make it to the Albany, N.Y., airport, dropped to the ground, slammed into a house and came to a halt.
There was no explosion. There were no flames. Yet 14 of 36 passengers aboard the jet were killed. The force of the crash, which jolted the house off its foundation, ripped seats loose from the aircraft`s floor and hurled the passengers forward through the cabin.
”They were all trapped in the seats,” a rescue worker said. The seats were ”like dominoes, piled on top of each other.”
The crash took place in 1972, but it vividly illustrates something that remains true. Even in accidents that are otherwise survivable, air passengers face an array of dangers–any one of which can kill them.
People aboard the Aeromexico jet that collided with a single-engine plane over Cerritos, Calif., in August were doomed because of the craft`s uncontrolled plunge from 6,000 feet. But many crashes take place under far less dire conditions.
In fact, the National Transportation Safety Board estimates that of all airline accidents–defined as incidents that result in serious injury, death or serious damage to the aircraft–more than 60 percent are survivable.
And ”in most survivable accidents, the majority of people should be able to get out,” said Matt McCormick, a safety board investigator. ”The opportunity in most cases is there.”
So why do people die?
”As the airplane starts to decelerate, everything begins moving forward,” said Wayne Williams, president of the National Transportation Safety Association, a Florida-based advocacy group. ”If the legs of your seat fail, the seat assumes the speed of the plane at impact.”
If seats don`t uproot or crumple dangerously, ”you bend forward from your seat belt very quickly, and just that can cause injury,” Williams said. In addition, your head may slam against the seat in front and your legs may fly off the floor ”with enough force to fracture them on the bottom of the seat in front of you.”
”If latches fail on overhead bins, you have missiles that assume the speed of the aircraft going through that cabin forward,” Williams said.
Then, there`s the most deadly peril–fire.
Safety critics charge that the Federal Aviation Administration has a long and disturbing history of listening too closely to the pleas of cost-conscious manufacturers and airlines when it comes to proposed measures that would improve crash survivability. FAA officials deny the allegation.
would result in strengthened seats is one of the most significant.
Under current FAA regulations, seats must be able to withstand a forward load of 9 g`s–nine times the force of gravity.
But the human body can withstand forces nearly three times greater than that, according to safety advocates who scoff at the present standard as a relic of the 1950s.
The proposed rule, now out for public comment, would increase the forward-impact requirement to 16 g`s, the force of a person hurtling ahead at 44 feet per second who comes to an instaneous dead stop. It also would beef up the standards for lateral, rearward and up-down crashworthiness.
Moreover, the rule calls for a critical change in the method of determining whether seats meet strength requirements. Presently, a ”static” test is used, in which constant pressure in one direction is applied until the seat fails.
The new rule would require ”dynamic” testing, using dummies in seats mounted on a powered platform, that would better reflect the real-life forces in a crash.
Safety proponents are not agreed on the adequacy of a 16-g standard because, they say, some people are able to survive greater impacts. They also are alarmed about a provision that would make the rule apply only to airplane models not yet on the market–ignoring thousands of aircraft that will be in use for years to come.
But they applaud the proposed regulation nevertheless.
”This is probably the greatest step forward taken by the FAA in the last 20 years,” said Harry Robertson, president of the Crash Research Institute, a Tempe, Ariz., consulting firm. ”We could argue all day long that it should be a little better. But for God`s sake, get it enacted so we have a solution coming down the road.”
The rule also would require modifications for seatbacks that would lessen the risk of head and leg injuries, something designed to allow passengers to retain consciousness and the mobility necessary to get out of the plane once it comes to a stop.
Looking beyond the 16-g seat, some safety experts believe that rear-facing seats hold the promise for even better survivability.
”Of all the things we could do, that is absolutely the best,” asserted Williams of the safety association. ”If you are facing rearward as the airplane decelerates, your whole upper body from your hips up is pressing you against that surface.
”You are not bending violently over your seatbelt. You legs are not flailing.”
But Caesar Caiafa, a crashworthiness expert at the FAA`s Technical Center in Atlantic City, said that rear-facing seats have drawbacks, too: For example, the risk of rolling or sliding out on impact, or being struck in the face by objects–ranging from soft drink cans to carry-on luggage–flying forward through the cabin.
In addition, structural elements of the plane would have to be strengthened.
Anything that would increase an airplane`s weight is given close scrutiny by the FAA, as well as airlines and manufacturers, when rules changes are considered. That`s because every extra pound on a plane translates into roughly 22 additional gallons of fuel burn a year.
As one federal safety expert candidly put it, ”Safety is a compromise with economics.”
Thirty-g seats could be required, he said. ”But you would have to build a platform so the attachment points to the floor could support those forces. When you beef up the floor, you have to beef up the shell around it and, all of a sudden, you have increased weight substantially and, therefore, cost.”
On the other side of the equation is the number of lives that would be saved. But the 1972 Mohawk crash was an aberration, the expert said. Deaths caused by seat failure have been rare in recent years.
Fatalities from fire and smoke are another matter, however. An inferno last year aboard a British Airtours Boeing 737 in Manchester, England, offers a recent example.
The jet was roaring down the runway for takeoff when a part in one of its engines failed, shooting metal through the fuel tank in the wing. Though there was no crash and though the plane came to a safe stop near the airport fire station, 54 of 137 aboard were killed in the ensuing blaze.
The amount of time that airplane cabin materials can resist igniting is an important factor in the ability to evacuate after an accident.
Until two years ago, a so-called ”Bunsen burner” test was the only one applied to seat flammability. In effect, seat materials had to withstand only the heat generated by a dropped cigarette or match without catching fire.
But a new rule now in effect calls for a much more stringent test. Under the revised standard, a pint of gasoline poured on a seat and set aflame probably would burn itself out without causing the seat to catch fire, said Richard Hill, a fire expert at the FAA Technical Center.
Airlines have until next year to complete outfitting their seats with new materials, Hill said. They are permitted to choose between fire resistant foam or fire-blocking cloth installed under the upholstery.
Because the foam is nearly four times the weight of commonly used urethane–about 15 pounds a seat–the popular choice is the cloth, developed by chemical companies about five years ago as they cast about for replacements for asbestos.
The material costs about $20 a square yard. A typical seat requires 2 to 2 1/2 yards.
Though increased flammability standards also have been applied to other cabin materials, the best that can be expected might be a minute of extra time to evacuate if the fire begins outside the cabin. But under the worst conditions–an accident in which the fuselage is ruptured and heavy winds fan flames, for example–the upgraded regulations mean little.
That`s why finding ways to prevent fires in the first place is so important.
Researchers are looking at fuel cutoffs to engines, increasing the thickness of ”impact areas” on planes and developing ways to improve fuel containment in accidents.
Some safety proponents also believe that highly impact-resistant rubber-like bladders, similar to those used in Indy race cars, could be adapted to airliners.
But Bill Westfield, an FAA engineer, sees the greatest promise in something called anti-misting kerosene, or AMK. Jet fuel does not burn readily in liquid form, but it is highly combustible as a mist, the form in which it is fed into engine combustion chambers.
In a crash, fuel from ruptured tanks can vaporize into the air, quickly transforming into a fireball when ignited by a spark.
AMK contains an ingredient, called FM-9, that prevents misting. A centrifugal pump mounted near the engine alters the FM-9`s molecular properties so the fuel can mist just before it is introduced into the power plant.
If the extra cost component of the fuel were passed on to passengers, Westfield said it would add only 1 1/2 percent to the price of a ticket for a 1,400-mile trip, probably less if AMK became widely used and competition forced prices down.
But AMK suffered a serious setback two years ago in a highly publicized test featuring the planned crash of a Boeing 720B in the California desert.
The remote-controlled jet landed short of its intended touchdown, hitting at the wrong angle a giant metal shear installed on the ground. The shear was supposed to slice through a wing tank to ensure fuel spill, but instead penetrated one of the plane`s engines. Hundreds of gallons of fuel poured onto the hot power plant and a huge ball of fire quickly engulfed the plane.
But, Westfield contends, it did not provide a fair test of AMK. ”My assessment hasn`t changed one bit,” he said. ”I still feel it is an excellent fuel and an excellent way to prevent post-crash fire.”
Indeed, FAA experiments have indicated that AMK could have made a life-saving difference in the Manchester accident. ”Assuming there was a fire, we feel it would have been retarded,” Westfield said.
No FAA endorsement of AMK is in immediate sight. But, Westfield said, the agency hasn`t given up on the fuel. More research is planned.
