MENEMSHA - Investigators yesterday located what they believe was the ''splash point'' where John F. Kennedy Jr.'s plane plunged into the ocean, but a rapid deployment of scuba divers to two nearby targets failed to turn up bodies or wreckage.
The site 71/2 miles southwest of Aquinnah on Martha's Vineyard was pinpointed using a new and more chilling account of the plane's final moments.
As he navigated through the inky night, Kennedy began an unexplained right turn, then suddenly dived toward the water at roughly 10 times the normal rate of descent, even faster than previously believed.
Some aviation authorities said the new information suggests Kennedy's plane corkscrewed into a ''graveyard spiral,'' but investigators declined to comment.
Investigators also declined to speculate on the force of the impact or its effect on the plane or its passengers. However, chief investigator Robert Pearce of the National Transportation Safety Board said: ''I'm sure you can draw a conclusion by the debris we've been bringing in, which is fragmented.''
A source familiar with the investigation said searchers ''are not very hopeful about the condition of the bodies.''
Coast Guard officials said the two target areas were 115 feet below the ocean surface, but the search was complicated by 52-degree water at the bottom, strong currents, and visibility of less than 8 feet. Divers earlier yesterday ruled out four other targets identified by sophisticated sonar vessels, leaving 13 or 14 potential debris sites to be examined during the effort to find the plane and the remains of Kennedy, his wife, Carolyn Bessette Kennedy, and her sister Lauren Bessette.
Also yesterday, a Federal Aviation Administration source said the agency was considering disciplining an employee who failed to follow up on a telephone inquiry about Kennedy's plane 25 minutes after it fell off radar screens Friday night. The source said FAA officials planned to interview the unidentified employee before deciding what action, if any, to take.
The call, a transcript of which was published yesterday in the Globe, was made by a Martha's Vineyard Airport employee, Adam Budd, on behalf of a couple who had come to the airport to meet Lauren Bessette. Budd called an FAA outpost in Bridgeport, Conn., mentioning Kennedy by name, offering two possible identification numbers for his plane, and asking whether it was possible to track the airplane because ''they wanna know, uh, where he is.''
As the search dragged through a fourth unproductive day, Kennedy's sister, Caroline Kennedy Schlossberg, emerged from seclusion. First, she and her husband went on an hour-long bicycle ride near their Bridgehampton, N.Y., summer home, where a flag flew at half-staff. Later she went for a drive with an entourage that included two cousins, television newswoman Maria Shriver and William Kennedy Smith.
Talk of memorial services also began in earnest, and there were reports that the Kennedy family is considering a service tomorrow or Friday at the Church of St. Thomas More in Manhattan, where Jacqueline Kennedy Onassis sometimes worshipped.
There was no official word where Kennedy and his wife might be buried, but workers at Arlington National Cemetery apparently took it upon themselves to measure the plot where Kennedy's parents, infant brother Patrick, and a stillborn sister are buried. Sources close to the family, however, said there are no plans to seek permission for burials at Arlington.
The Bessette family released no information on memorial plans for Lauren Bessette.
At a late afternoon briefing, Pearce, the chief crash investigator, provided grim new details of the final minutes of the tragic flight.
About seven minutes before the plane crashed, Kennedy was flying - apparently uneventfully - at 5,600 feet. He was 34 miles from Martha's Vineyard Airport.
At that point, Kennedy was heading in an easterly direction and traveling at about 160 knots, which translates into a ground speed of 184 miles per hour. He then began descending at a rate of about 700 feet per minute. Pilots familiar with Kennedy's Piper Saratoga II said that was a normal, if somewhat rapid, rate of descent.
That initial descent continued for about five minutes, at which point he was 20 miles from the airport at an altitude of 2,300 feet. He then started to turn to the right, off course from Martha's Vineyard. The plane rose to 2,600 feet at the start of the turn.
Kennedy remained at that altitude for one minute, on a southeasterly heading, putting him about 18 miles from the airport. Kennedy then began another descent at a rate of 700 feet per minute, and started a turn back to the east.
''Now, 30 seconds into that maneuver, the airplane started a turn to the right and a rapid descent,'' Pearce said. He said an NTSB computer analysis determined the plane was racing downward in excess of 5,000 feet per minute. On Monday, NTSB officials estimated the descent at 4,700 feet per minute. The descent gauge on Kennedy's type of plane goes only to 2,000 feet per minute.
Veteran pilots say a descent of 5,000 feet per minute at that altitude would be nearly impossible for someone with Kennedy's experience - or even considerably more - to correct.
Investigators declined to say why Kennedy might have undertaken the previously undisclosed maneuvers. But pilots and aeronautics authorities speculated he might have become disoriented on a night with heavy haze and little moonlight.
Coast Guard Rear Admiral Richard Larrabee said sonar scans by two boats from the National Oceanographic and Atmospheric Administration, the Rude and the Whiting, and the Coast Guard cutter Willow had identified two clusters of dive targets 5 miles apart off Martha's Vineyard.
Divers from the State Police and the Navy vessel USS Grasp ruled out four targets from an original group of 10, while the sonar boats added seven or eight more targets that will be searched in the days ahead.
Also yesterday, FAA officials continued their public defense of the employee who received the phone inquiry about Kennedy's plane, saying the 10:05 p.m. Friday call was not specific enough to prompt a response.
''We wish very much that we'd had more information, but we had no information that the plane was in trouble or overdue,'' said FAA spokesman Eliot Brenner. ''We do not provide information on private citizens or private aircraft over the telephone.''
The FAA source said that although they do not believe the employee acted improperly, officials are upset that the man did not come forward to tell superiors about the call when it became clear the plane was missing.
Under FAA policy, if a pilot files a flight plan, no action would be taken on such a call until a plane was at least 30 minutes overdue. In cases such as Kennedy's, where no flight plane was filed, the FAA takes no action until a plane is an hour overdue and reported so by ''a reliable source.''
Furthermore, FAA policy is not to release information over the telephone unless the caller is known to the FAA. In the case of a plane involving a Kennedy, the FAA source said, officials might be even more reluctant to release information out of fear that the caller could be ''a nutcase or paparazzi.''
A second FAA source would not discuss the possibility of discipline, saying, ''He did the right thing. He did not release private information. But in retrospect, it might have been useful to ask some questions.''
As it turned out, no action was taken until more than four hours after Budd's call. The first response resulted from a 2:15 a.m. Saturday call to the Coast Guard by a Kennedy friend identified as Carol Ratowell. An official search and rescue mission began just over an hour later, at 3:28 a.m.
Until the plane is found, there is no way to know whether a quicker response might have made a difference in the survival of Kennedy and the Bessette sisters. Based on radar readings, the plane made a sharp plunge into the sea, and aeronautics authorities said there was little chance of survival.
A spokesman for the country's largest general aviation association said he agreed with the FAA's explanation that the call was ignored because Budd never used the precise language required in such a situation.
''It was asking the specialist to read someone's mind and read between the lines,'' said Warren Morningstar, director of media relations for the Aircraft Owner and Pilots Association, a lobbying group with 340,000 members. ''Their primary job is pilot briefings, and I would have a hard time throwing stones at them for this.''
While Menemsha played host to a media encampment as the launch site for divers - with satellite trucks lining the shore - about 15 miles away tourists in Oak Bluffs ambled oblivious to the frenzy.
Marie Fischer, a parking and traffic enforcement officer, said, ''It was just another day at the beach. It's pretty quiet today, I don't know why.''
Beyond Martha's Vineyard, the commercialization of the tragedy moved into high gear. Just one indication was the activity at the on-line auction house eBay.com. By late afternoon, there were 289 items for sale linked to John F. Kennedy Jr., including a signed credit card slip that had attracted 17 bids, the last one for $635. Someone also was offering the Internet domain name carolyn-bessette.com for $35,000. There were no bidders.
Globe correspondent Jennifer Babson contributed to this report from Menemsha.