JET FIRE CAUGHT ON TAPE : FLIGHT 592 PILOTS RECEIVED WARNING.

Byline: Michael Wines The New York Times

The pilots of ValuJet Flight 592 were some six minutes into a routine flight out of Miami when someone apparently burst through the cockpit door to warn of a fire in the passenger cabin, according to investigators' first analysis of the tape from the jet's battered cockpit voice recorder.

``There was also an indication from the cabin that there were problems obtaining oxygen,'' Robert Francis, the vice chairman of the National Transportation Safety Board, said at a briefing Monday.

Beyond that, Francis said, the first review of the recorder disclosed little about the May 11 crash, which killed all 110 crew members and passengers aboard the DC-9.

Francis refused to speculate on the meanings of any of the cockpit exchanges or to say whether the shortage of oxygen referred to breathable air in the cabin or the functioning of the oxygen masks that are supposed to drop automatically from above passengers' seats in emergencies.

He said that he had not personally listened to the recording but that he had been told that it was extraordinarily difficult to decipher and yielded little else on its first playing.

``At this stage, we have not had the opportunity to do enough work on the tape to say how much help it's going to be,'' he said. ``This is not going to be a matter of hours, but of days.'' The recorder was pulled out of the muck of the Florida Everglades crash site and flown to Washington on Sunday.

At the briefing, the safety board displayed the thick aluminum recorder case, roughly the size of a hard-cover book, that held the flight recorder in the jet's tail section. In the center of the case was a deep puncture, evidence of an immense collision between the recorder and something else as the plane hit the ground and disintegrated.

The penetration of the recorder case, which is meant to withstand the worst of crashes, underscored the speed at which the jet plummeted when it fell 7,500 feet into the swamp.

``It required an enormous amount of force, whatever went into it,'' Francis said. ``We were extremely fortunate that we came out with an intact piece of tape.''

The tape did appear to confirm that crew members first found evidence of a fire in the passenger cabin and not the cockpit. Searchers said Sunday that they had found a passenger seat frame with melted aluminum that pointed to a cabin-area fire.

But federal investigators have said they suspect the fire began in the jet's forward cargo hold, directly below the cabin. A principal theory is that one or more oxygen generators the jet carried in its forward cargo hold accidentally activated.

That would have produced intense heat and could have started an explosion in any of several aircraft tires that also were stored in the hold.

Francis stressed on Monday, however, that experts had not yet settled on a specific explanation and that they would continue to search for clues at the Everglades crash site.

In particular, he said the searchers would look for any parts that helped control the plane's flight and for a set of circuit breakers controlling the fuel pumps, which mechanics had worked on in Atlanta, the plane's last stop before it flew to Miami.

The disclosure that someone had to alert the pilots to the fire also raises the question, perhaps never to be answered, of whether the crash might have been averted had the DC-9 been equipped with smoke detectors in its cargo hold.

The National Transportation Safety Board had recommended before the accident that cargo areas in passenger aircraft be outfitted with fire-detection systems. But the Federal Aviation Administration, which regulates the industry, has not acted on the safety board's advice.

Despite the damage to the flight recorder, safety officials were hopeful of finding more clues to the crash. The tape ``had obviously been subjected to impact and showed signs of that,'' Bernard Loeb, the director of the board's office of aviation safety, said after Monday's briefing. It also had soaked in the brackish water of the Everglades for two weeks.

Even so, Loeb added, ``The tape was in generally good condition.'' The greatest challenge facing the engineers who are trying to pick scraps of conversation from the tape is not its condition, he said, but the background noise from the jet's cockpit.

Loeb said such noise is common on tapes from cockpit recorders, and varies according to the microphones in use in the cockpit at the time. He said he was optimistic that much of the noise could be removed by electronic filters and other means.

The tape is designed to record continuously, saving the most-recent 30 minutes of data, and Francis said a full half-hour of conversation appeared to be on the recording.

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PHOTO Vernon Ellingstad of the National Transportation Safe ty Board displays fragments of the ValuJet Flight 592 cockpit voice recorder.

Associated Press