DISABLED JET STAYED ALOFT BEFORE FINAL BLAST, RADAR SHOWS.

Byline: Matthew L. Wald The New York Times

Radar records show that TWA Flight 800 apparently continued to fly for at least 24 seconds after the cataclysmic event that doomed it, raising the possibility that some of the passengers and crew may have been alive in the last horrifying seconds before the crippled jet broke apart in a fireball, investigators said Friday.

The radar information does not give a clue as to whether the cockpit crew had any functioning controls to work with after the plane was disabled at 13,700 feet by either a mechanical problem, a bomb or a missile - investigators still do not know which.

But the investigators said the records indicate that the jetliner's engines probably continued to run as it moved over the water at more than 400 miles an hour. The plane was also descending rapidly, and by the time it reached about 8,500 feet, a fireball erupted, fed by the jet fuel that investigators presume was gushing from the plane's tanks.

The scenario, based on information from a radar dish that takes 12 seconds to make a 360-degree sweep of several thousand miles, did not make investigators any more certain of the cause of the problems. But it did help establish the framework for a sequence of failures.

According to the investigators, the radar made two sweeps after the initial event in which the plane appeared to be basically intact. But by the time the radar made its third 12-second sweep, two pieces of the plane became visible on radar.

Federal officials said that there were no signs of problems on either the flight data recorder or cockpit voice recorder except for a loud noise at the end of the voice recorder, and except for the obvious fact that they quit working a fraction of a second after the noise was heard.

Investigators also said they had found two of the plane's four engines. But they said they had decided to delay raising them and assessing their condition - which could provide major clues - because doing so would delay the recovery of bodies. Searchers have now brought up the remains of nearly two-thirds of the 230 people on board, and nearly half have been turned over to relatives.

According to the National Transportation Safety Board, the plane's last moment of normal functioning was about 8:31:12 p.m., when the aircraft was climbing toward 15,000 feet with its wings level. Within the next 12 seconds - the time that radar at Islip, N.Y., takes to make a full-circle snapshot of planes in its sector - the beacon that broadcast the plane's identity and altitude had failed.

About the same time, possibly at the same instant, power was cut to the flight data recorder and the cockpit voice recorder. And sometime around then the pilots' radios probably ceased to function.

But the plane was in the air for an additional 2.5 nautical miles, 41 seconds more. For at least 24 of those seconds, the jetliner continued at a more or less constant speed over the water, about 380 knots, but its speed through the air was apparently rising rapidly, because it was descending to the point where it became a fireball. A normal airliner descends about 1,500 feet per minute; this would have been about five times faster.

In that rapid descent it was apparently also shedding some large, though relatively light pieces, which were found in what investigators now call Debris Field No. 2, an area southeast of the plane's track over the water. These may be sides of the fuselage, investigators say.

As technicians in Washington studied the recorders, investigators here laid out the following chronology:

The plane, having arrived from Athens earlier in the day with no mechanical problems, took off lightly loaded from John F. Kennedy International Airport and climbed at the standard speed of 250 knots, or 287 mph, to 10,000 feet. Above that height it began climbing with its airspeed indicator at 300 knots or 345 mph.

But as the air gets thinner with altitude, an airspeed indication at a constant speed means increasing airspeed over the ground; that, plus a partial tail wind of 20 knots put the airplane's speed over the water at 279 knots at the time of the first event.

That event probably happened at 13,700 feet, because that is the last altitude reported by the on-board transponder, which gives the plane's identity and altitude. By the time the radar looked again, there was only the ``primary return,'' or ordinary radar echo. From then on, the radar picture was only two-dimensional.