Ground radar that could have aided an air traffic controller was not working the night a USAir jet and commuter plane collided in a fiery runway crash that killed 33 people, federal authorities said.

The National Transportation Safety Board, which is investigating the crash, already has determined that a controller who showed signs of preoccupation and confusion and who had trouble communicating with several of the planes she was guiding directed the ill-fated planes onto the same runway.NTSB officials revealed at a news conference Sunday that the ground radar system used to assist controllers in tracking planes on the runways at Los Angeles International Airport during darkness or foul weather, was not functioning Friday night when the planes collided shortly after 6 p.m.

Investigators have found a maintenance report on the radar system written at least 18 hours before the crash, NTSB spokesman Ted Lopatkiewicz said.

"There was a notation that it was out of service, and no notation that it had been repaired," he said.

Although the ground radar systems are rare - only about a dozen airports have them - an internal memorandum at Los Angeles International Airport said the tower is required to use the system between sunset and sunrise and at other times when visibility of planes is poor, Lopatkiewicz said.

On Sunday, a crane dissected the tangled wreckage of the USAir Boeing 737-300 and the SkyWest commuter plane, a Fairchild Metroliner III, allowing authorities to get in and recover the remaining bodies.

The Los Angeles County coroner's office put the final death toll at 33.

The NTSB inspected the smashed fuselage of the two planes Sunday and found that some of the passengers died in their seats, while others perished trying to escape, a spokesman said.