The description by National Transportation Safety Board (NTSB) officials yesterday of the final seconds of Sunday's crash that killed 217 people shows that the plane did not go straight down, said John Clark, deputy director of the NTSB's office of research and engineering.

The NTSB said the Boeing 767 was cruising at 33,000 feet a half-hour after leaving New York for Cairo when it suddenly descended 16,300 feet in a straight line within 40 seconds. At the time, the plane had a ground speed of about 600 knots, or about 1,110 kph.

Then the plane pitched up and climbed 8,000 feet. Clark said he did not know the cause of the climb, and refused to speculate on whether it was a catastrophic event on board or whether the pilots were struggling to control the aircraft.

Meanwhile, efforts to retrieve the black boxesand pieces of the aircraft were delayed because of high winds following a storm that was expected to prevent most of the recovery efforts until at least the weekend.

Preliminary analysis of the radar data appeared to backup the conclusion that the plane broke up before it hit the ocean, Clark said, but he refused to comment on what the new information would mean to investigators or to consideration of thrust reversers as a possible suspect in the crash.

The information was provided by the US air force after an analysis of radar tape.

Officials said it was likely that an analysis of the black boxes, when they are recovered, would tell whether a thrust-reverser had been activated in the air, an event that caused a Boeing 767 to crash in Thailand in 1991. The reverser is intended to slow a plane after landing.

"We have no evidence at this time that the thrust reverser system played any role in this accident," James Hall, chairman of the NTSB, said at the evening briefing.

A top Egyptian aviationofficial said the reverser could not have caused the crash. Even with a reverser malfunction, the pilots still would have had time to radio a distress call, said Isam Ahmed, head of Egypt's civil aviation institute.

A former NTSB investigator, Barry Trotter, said that information released so far leads him to consider the thrust reverser as a possible cause.

The reverser wasn't working on one of Flight 990's two engines and was deactivated sometime before the crash, according to investigators.

Greg Phillips, NTSB's chief crash investigator, added that investigators have not yet seen the plane's maintenance records - or major pieces of the plane itself.