Seat Design Cited in Survival of Many in DC-10 Crash

WASHINGTON —  While blind luck and fortunate circumstances helped more than 180 passengers survive the fiery DC-10 crash in Iowa, firmly anchored seats were cited Friday as an important factor in keeping the death toll lower than initially feared.

A number of experts have said they were astonished at the relatively low death toll in the crash of United Airlines Flight 232, bound from Denver to Chicago on Wednesday.

Experts said that many of the survivors lived because their seats remained fastened to the aircraft floor, sparing them from potentially fatal injuries as the jetliner crashed into the ground, burst into flames and separated into three sections.

Most of the passengers injured or killed were thrown out of the airplane and hurled down the runway, still strapped into their seats, according to David J. Greco, emergency medical director of Marian Health Care Center in Sioux City.

Massive Injuries

“They looked as if they had been rolling for up to half a mile at high speeds,” Greco said, noting that many suffered massive head, arm and leg injuries.

The Federal Aviation Administration has proposed a rule--which must be approved by the secretary of transportation--that would require airlines to install seats with even greater crash resistance by June, 1995.

“Stronger seats are less likely to break out of the seat tracks. If the seats break out, it’s rather devastating,” said Henri Branting, manager of the FAA’s technical analysis branch.

“I wouldn’t be the least bit surprised if the NTSB (National Transportation Safety Board) in their final report (on Wednesday’s crash) urges the FAA to expedite the rule,” said Nancy Gilmer, coordinator of air safety and health research for the American Assn. of Flight Attendants.

Currently, aircraft seats are designed to withstand up to nine G-forces, or nine times the force of gravity. The proposed rule would order installation of seats capable of withstanding 16 G-forces, said Gilmer, who noted that most automobile seats can withstand up to 20 G-forces.

More Impact

Stronger seats can absorb more impact in a crash, Gilmer said, and they are less likely to separate from the floor.

United Airlines spokesman Herb Gardner in Chicago said that he could not discuss the type of seats installed in the DC-10 that crashed Wednesday because the company has turned all maintenance records over to the NTSB. “I’m certain the seats comply with current FAA standards,” he said.

The DC-10 came down in a cornfield yards short of a runway at Sioux City after the pilot reported that he had lost all control. The disaster apparently was caused by an explosion in the plane’s tail engine and the subsequent failure of its hydraulic systems.

Heading into what experts called a “controlled collision” with the runway, the plane pitched to the right and scraped its right wing. It cartwheeled, breaking into pieces as it rolled.

Many of the survivors were seated in Rows 9 to 19 in a section of the plane that landed upside down after the crash. They were able to unbuckle their seat belts and walk away from the wreckage.

A number of unusual circumstances enabled such a large number of people to survive, experts said.

Because the aircraft was in a landing position, “it hit in a flat manner,” said Allan Mears of the Flight Safety Foundation. “The clipped wing caused it to roll, and the impact forces were not tremendous.”

The DC-10 broke into three sections: the cockpit, the main body and the tail end of the plane. “Those (seated) away from the immediate break points probably had a good chance of surviving,” said Wayne Williams of the National Transportation Safety Assn.

But experts said that there is no predictably safe place to sit on an airplane since the impact of every crash differs. “There are too many variables in an accident,” said Michael Benson, spokesman for the National Transportation Safety Board here.

Even though the wings increase the strength of the middle section of a plane, that area is surrounded by fuel tanks. Flight 232, which had flown for more than two hours before it crashed, may have used most of its fuel, lessening the fires that broke out when it crashed.

“Fire, smoke and toxic fumes really kill most people in these crashes, rather than the crash itself,” said Edmund J. Cantilli, executive director of the Institute for Safety in Transportation.

Fire-resistant seat cushions, required in all airplanes under a 1988 FAA rule, probably slowed the spread of the fire in the cabin. In the past, seat cushions made of polyurethane foam spread fire quickly, emitting toxic gases in the process.