LOS ANGELES, FEB. 3 -- The following is a chronology compiled from tapes of the moments before USAir Flight 1493 and SkyWest Flight 5569 collided Friday at a Los Angeles International airport runway. The details were related by National Transportation Safety Board spokesman James Burnett.

6:03:37 p.m. PST: SkyWest Flight 5569 tells air traffic controllers it is at Taxiway 45 and ready for departure.

6:03:40 p.m.: The controller tells the commuter plane to "hold short of Runway 24-Left," or to not enter the runway yet.

6:03:45 p.m.: USAir Flight 1493 says it is approaching and requests clearance for landing. The request is not acknowledged.

6:04:44 p.m.: The controller tells the SkyWest pilot to "taxi into position and hold" at the beginning of the runway and says there is cross traffic down the airfield.

6:04:48 p.m.: The SkyWest pilot confirms he has followed the controller's directions.

6:05:29 p.m.: USAir Flight 1493 asks for clearance for landing a second time. Again, no one acknowledges.

The controller asks the pilots of at least two other aircraft whether they are on Runway 24-Left. The controller also repeats instructions to an Aeromexico flight that is coming in for a landing.

6:05:52 p.m.: The USAir pilot asks a third time for clearance to land.

6:05:56 p.m.: The controller gives USAir clearance to land on Runway 24-Left. The SkyWest jet is at the entrance to the runway.

An electronic squeal is heard on the tape.

6:07 p.m.: The controller announces an accident has been observed. Speaking "very coolly," she asks who needs help.

6:07:04 p.m.: An unidentified voice is heard saying, "What the hell?"