THE CRASH OF EGYPTAIR 990: THE OVERVIEW; EGYPTIAN JET, CARRYING 217, PLUNGES INTO THE ATLANTIC; CAUSE OF CRASH IS UNKNOWN

An Egyptian jetliner bound from New York to Cairo overnight with 217 people aboard plunged suddenly into the Atlantic southeast of Nantucket Island 33 minutes after takeoff early yesterday. One body and some debris but no survivors were found in an exhaustive daylong search, and the disaster's cause was not immediately known.

The aircraft -- Egyptair Flight 990, a Boeing 767-300 carrying 199 passengers, many of them Americans -- and 18 crew members, left Kennedy International Airport at 1:19 a.m. (Eastern Standard Time) on a scheduled 11-hour nonstop flight to the Middle East. While takeoff was late, everything seemed normal.

But at 1:50, with the twin-engine, wide-bodied plane cruising at 33,000 feet in a clear night sky lit by a half-moon, something went terribly wrong, and the aircraft began plummeting, out of control, aviation officials said. There was no distress call from the cockpit, the last voice contact with ground controllers having been routine. Two minutes later, the plane vanished from radar screens.

It was unclear what happened: Had an explosion erupted? Was there a mechanical failure? Was the aircraft even in one piece as it went down? All that was known was that the jetliner, without warning, plunged out of the sky and into the dark, rolling sea about 60 miles southeast of the Massachusetts island of Nantucket.

Federal officials said radar sweeps at 12-second intervals showed that the aircraft fell from 33,000 feet to 19,100 feet -- a drop of 13,900 feet -- in 36 seconds, indicating that it was falling ''like a rock,'' as one aviation expert put it. The rate of descent was more than 23,000 feet per minute, while a normal descent is 1,500 to 2,000 feet a minute.

Even if the plane was still intact as it fell, aviation experts said, the high-speed impact with the water would have shattered it, and the chance that anyone survived was small. The water was a chilly 59 degrees, and 250 to 270 feet deep, a cod and tuna ground that would have been dotted with fishing boats and lobstermen in early October but was all but deserted early yesterday.