New radar analysis of EgyptAir Flight 990 shows the aircraft fell at a rate of about four miles a minute when its descent started and remained largely intact for more than 40 seconds before beginning a gradual turn to the right--movement that suggests the aircraft started to break up before it hit the Atlantic.

The new information, combed from radar sites in Boston and New York, shows that the plane was in a forward dive when it descended from 33,000 to 16,700 feet. Then the aircraft began a right turn from 70 degrees to 130 degrees over the next 37 seconds, the data shows.

National Transportation Safety Board officials would not speculate on the new radar analysis. But aviation experts said the movements are consistent with a plane beginning to break up as it was buffeted by the forces of its fall, perhaps breaking the sound barrier in the process.

The new information came as search vessels located a major debris field today more than 250 feet below the surface where Flight 990 is thought to have crashed and reported hearing strong signals from a second recorder from the Boeing 767.

However, a gale moving up the East Coast churned seas eight to 10 feet high, forcing Coast Guard and Navy ships to withdraw to safe harbor. Coast Guard Capt. Russell Webster said it might be two days before they can return to the area 60 miles off the Massachusetts coast where the plane went down, killing all 217 people on board.

The weather did little to dampen the obvious encouragement of investigators who would be faced with a far more arduous investigation without the plane's flight data recorder and cockpit voice recorder--also known as the "black boxes." Gregory Phillips, investigator in charge for the NTSB, called the development "a very good start to what may be a very long investigation."

U.S. Navy Capt. Jeff Graham said that as soon as the Navy recovery ship USS Grapple can enter the area, its top priority will be recovery of the two black boxes.

The recorders are considered particularly important in this investigation because there are few other clues. The crew made no distress call before the beginning of the plunge from 33,000 feet--a rarity for an airliner that encounters a serious problem while at cruising altitude.

The data recorder on Flight 990 makes 55 measurements of the plane's movements, control inputs and control surface movements--enough to give a detailed picture of almost every nuance of the plane's last moments. The safety board has been hampered in other investigations because of recorders that had as few as 11 measurements or parameters. The plane originally had a recorder with 27 parameters, but EgyptAir had upgraded the recorder.

Among the parameters measured is whether there was any movement in the plane's thrust reversers, a form of engine braking device that projects the jet blast in a more forward direction to slow aircraft on landing. One of the two previous 767 crashes, involving a Lauda Air plunge into the jungles of Thailand, involved accidental deployment of a thrust reverser in flight. Investigators later determined that a thrust reverser deployment on that particular airplane set up wind currents under the wing that immediately destroyed the lift on that wing.

The Federal Aviation Administration ordered all 767s to be equipped with a new separate lock on each thrust reverser, and both EgyptAir and Boeing said that work had been accomplished on the crashed plane.

However, because of the similarity of a sudden dive, investigators cannot overlook the possibility of a thrust reverser problem. A piece of an EgyptAir 767 thrust reverser broke off in flight in 1997, but the thrust reverser did not deploy, and the plane landed safely.

Sources said there has been at least one report from a previous crew of a thrust reverser problem with the crashed plane. However, the source said data being developed from radar strongly indicates that there was no thrust reverser deployment on the aircraft. The source said it hardly would be possible for a thrust reverser to deploy without jerking the plane's heading left or right, but radar data shows that the plane made no turns until more than 40 seconds into its dive.

The first recovery ship to arrive at the site of the accident, about noon on Monday, was the Coast Guard cutter Chinook, based nearby in New London, Conn. Its chief engineer, R.J. Burns, told reporters today that he immediately noticed the strong smell of jet fuel and that the waves had been smoothed out by an oily sheen. He said lots of debris was floating in patches, and the crew immediately donned masks and rubber gloves to begin picking up pieces. Burnes said he was affected by the scene, especially when the boat pulled up "little Disney rollerblades. That was kind of tough."

"I was thinking of the people and hoping it was quick--and what they were thinking for the last 30 seconds and what their families must be going through," Burns said.

Throughout the day, busloads of grieving relatives and close friends of the victims converged on the Doubletree Islander Hotel in Newport, R.I., thousands of miles away from the Egyptian airport where they had eagerly anticipated meeting their loved ones less than 72 hours ago. One of them, a 35-year-old Egyptian man who lost his brother in the crash, was taken by ambulance from the hotel this morning after he reported feeling dizzy, Newport police said. He was treated for stress at a local hospital.

One man who also was in Newport, Michael Crow of Seattle, lost four relatives in the crash and said he desperately wanted to know whether investigators had unearthed any clues. "You're left feeling like you're hanging, not knowing what's going to happen," he said. "I know it's going to be a long process, but we need to know why."

Officials today also clarified confusion over reports that a large piece of floating aircraft had been found. Webster said that on further interviewing the crew, it is likely that the crew of a helicopter that spotted the wreckage thought it was probably a luggage container. However, he said the object apparently sank before a boat could get to it.

Investigators said they still haven't ruled out any cause for the crash. But FBI officials say no information has been discovered that would lead to a conclusion that terrorists are responsible for the EgyptAir crash. "We don't have anything at this point to suggest criminal activity or any external force," a senior FBI official said. "There is no evidence and no intelligence of that nature."

Staff writers David A. Vise and Lorraine Adams contributed to this report from Washington.

CAPTION: Grieving families of victims disembark at airport in Warwick, R.I.

CAPTION: THE FINAL SECONDS (This graphic was not available)