"Give me a check at the end of the runway, USAir 172," said the voice from the control tower. "I'm looking for a 737."

Five and a half minutes earlier, Air Florida Flight 90 had taken off from National Airport in a blinding snowstorm. Repeated radio calls to it from the tower had gone unanswered and controllers were getting scared. Now one was asking an incoming USAir pilot to taxi his plane to the end of the runway, obscured by the falling snow, and look for the missing Boeing 737.

The tower's request and the growing fear of disaster are dramatically recorded in a transcript of air traffic control tapes released yesterday by the Federal Aviation Administration. The tapes, which were made before and after the crash of Flight 90 17 days ago, give no obvious clues to why the plane crashed but offer an inside account of how an airport responds to a disaster.

The contents of another tape important to the investigation, the cockpit voice recorder tape, have not yet been disclosed. This tape, contained in a so-called "black box," was recovered from the jet's wreckage by divers and contains the final words of the crew and noises in the cockpit.

After receiving the tower's request for help, according to the transcript, the USAir pilot responded: "Ah, about a thousand feet to the end and we don't see an airplane yet." Half a minute later, the plane reported: "Approach lights we can see them but no airplanes out to the north." Then the plane reports tracks at the end of the runway. But "I can tell I don't see any tails or any aircraft."

"Ah, hey, we may have to stop operations up here a bit," the tower told other planes after that. "I'll keep you advised . . . go into holding."

The crew's radio messages before take-off were routine, according to the transcript. The pilots received approval of their flight plan to Tampa at about 1:59 p.m. but were told the airport would be closed at least until 2:30. The runways were being cleared of snow.

" Does this look like a pretty good line-up or should we, ah, plan additional delay?" one of the plane's pilots asked the tower. He was told there might be more delays after the airport reopened. "Okay, we were due out at 2:15 and I was just wondering," he responded.

At 3:17 the plane radioed that it was ready to pull away from its gate, but was told "just hold it right where you are, Palm 90. Palm is a term for all Air Florida flights. I'll call you back." At 3:24 it got clearance to leave the gate and a pilot acknowledged with a simple "Palm 90 Roger."

At 3:38, while Palm 90 was apparently on a taxiway leading to the runway, the crew offered to pull over to let another plane pass and was told by the tower to do so.

An Eastern airlines pilot's comment a few seconds later, after being told to hold at certain runway markers, indicated the extent of the snowfall: "I don't have the slightest idea where the lines are," the pilot said. "They're all covered up."

At 3:59 the Air Florida jet was told to taxi up to the take-off runway and "be ready for an immediate" start. Seconds later, the tower broadcast "Palm 90, cleared for take-off," the signal to begin rolling. "Palm 90 cleared for take-off," one of the pilots responded.

The tower gave a final instruction: "No delay on departure, if you will. Traffic's two and a half out for the runway." This meant the Air Florida flight should not delay taking off, because another plane preparing to land on the same runway was two and a half miles away.

The final message from the Air Florida jet, recorded at 28 seconds before 4 p.m., was: "Okay."

There have been suggestions that the tower was pushing the plane to clear the runway, perhaps causing its pilots to take off in spite of any apprehensions they may have had. However, investigators familiar with the tape say that busy airports like National are routinely policed this way and that it presents no safety hazard.

Sixty-one seconds after that final message from the plane, apparently after the airport radar had picked up the plane on two sweeps and then lost it, the tower called out "Palm 90," There was no answer. Eight seconds later, the tower was on the air again: "Palm 90, contact departure control." No answer.

Though the plane's whereabouts were unknown, the controllers cleared another plane for take-off. Then the tower talked to a controller in the radar room. "You talking to that Palm--you talking to Palm?" the tower asked. "No, not yet," radar responded. The tower then tried again. "Palm 90, how do you read?."

Seconds later, there was apparently false hope. A controller said: "Oh wait, you got 'em." But there was no contact--the plane was already in the icy Potomac a mile north of the airport, and 74 of the 79 aboard were dead. "Palm 90, Palm 90, you on the frequency?" the controller asked. Then he called out simply, "Hey guy, hey guy." And again, 24 seconds later: "Hey guy."

Five minutes after Air Florida's last transmission, the controller called the USAir plane, which had just been cleared to land: "USAir 172, would you do me a favor? . . . Give me a check at the end of the runway, USAir 172. I'm looking for a 737."

There was apparently one more burst of hope. Seven minutes after the Air Florida plane left, an unintelligible message crackled across the radio. "Ah, who just called me?" the controller broadcast. But it was not Palm 90.

The transcripts do not indicate when the tower notified authorities that the plane was missing.