Investigators of the crash of Delta Air Lines Flight 191 believe the crew attempted to brake the plane to a halt on the ground after recognizing that it could not regain altitude.
The investigators based that preliminary conclusion yesterday on these findings:
* It appears from skid marks on the highway crossed by the plane that the aircraft was braking.
* A study of physical evidence and the flight data recorder indicates that the plane's ground spoilers and thrust reversers were deployed.
Ground spoilers are large metal sections atop the wing deployed perpendicular to the wing after the plane lands. They "spoil" the wing's ability to lift the plane and help keep it on the ground.
Thrust reversers are deployed after landing to reverse the direction of jet engine exhaust and assist in braking.
Yesterday's report means, one investigator said, "that the crew was trying to make the best out of a bad situation" last Friday.
The Lockheed L1011 jumbo jet bounced once and started breaking up but remained essentially intact until it slid into two water tanks at Dallas-Fort Worth International Airport. At that point, the tail section broke loose. Most of the 31 survivors were in that section, which did not catch fire.
Some have speculated that, if the water tanks were not in the plane's path, it might not have broken up and more aboard might have survived. However, investigators know that the plane was afire at the time it hit the tanks and that the tanks probably prevented it from plowing into two aircraft parked on a nearby ramp. One was fully fueled.
It is possible that the ground spoilers deployed when the plane first struck the ground, because they do so automatically when the landing gear turns or there is pressure on the landing gear struts. The deployment can be overridden by the crew, however, according to sources familiar with the L1011.
Ira Furman, a spokesman for the National Transportation Safety Board, said the precise death toll is unknown. Based on information from the Dallas County coroner, the board counts 130 deaths on the aircraft and one on the ground, in an automobile on the highway.
The cause of death in 77 cases was listed as trauma, in 15 as burns and in 38 as a combination of trauma and burns.
Investigators continue to concentrate on what type of weather system the crew saw when it began the approach to the airport. The leading suspect as a cause of the accident is a microburst, a type of wind shear that, at low altitudes, can deprive an airplane of the ability to fly.
The crew apparently thought the plane was entering nothing more lethal than a rain shower. No available weather report predicted thunderstorms, which pilots avoid.