SANDWICH TOWNSHIP, Mass. — The "splash-down point" of John F. Kennedy Jr.'s plane was roughly identified on Tuesday, and federal officials provided more details of the flight's final minutes.
As Kennedy descended toward Martha's Vineyard, in what appeared to be a normal approach, he sharply turned to the right and then the plane dropped rapidly to the water, diving at 10 times the normal rate, officials said Tuesday.
Robert Pearce, who is heading the investigation for the National Transportation Safety Board, said that about 35 miles from the airport the flight was normal, with the plane descending from 5,600 feet to about 2,300 feet. Then, about 20 miles from the airport, radar data released Tuesday indicated, the plane started turning to the right and climbed slightly back to 2,600 feet.
Kennedy leveled off, flew a short time more, began another turn to the right and then the plane suddenly dropped from the sky at a rate that may have exceeded 5,000 feet per minute.
The new data bolstered earlier analysis by air safety experts who said Kennedy suddenly lost altitude in an apparent "graveyard spiral," an indication that pilot error was the most likely cause of the crash. The aerodynamic forces on a plane in a graveyard spiral are so extreme that even expert pilots cannot recover.
Search crews, aided by radar, believe that the plane went down about 7 1/2 miles west of Cape Gay--the westernmost point of Martha's Vineyard. Global positioning satellites directed the U.S. Navy salvage ship Grasp to the area.
"We now have a much more accurate projection of where the splash-down point is," said Coast Guard Rear Adm. Richard Larrabee. "We are now concentrating on two targets of high interest in that area."
Navy divers spent Tuesday, the fourth full day of the search, examining one of the targets. They scoured the area, dropping as far down as 115 feet, but they were hampered by poor visibility.
As the sun went down, they were unable to locate any remnants of the plane. They will resume the search today.
Some more debris, however, including a head rest and a chunk from the cabin's lighting system, washed up on shore.
Meanwhile, the Federal Aviation Administration acknowledged that on Friday night it received a call from an intern at the Martha's Vineyard airport who asked for help in locating the plane that was carrying Kennedy, his wife, Carolyn Bessette Kennedy, and her sister, Lauren Bessette.
The airport intern called an FAA station in Bridgeport, Conn., at 10:05 p.m. at the request of a couple who was waiting at the airport to meet Lauren Bessette. The intern did not indicate that his inquiry was an emergency, but he casually asked if the FAA could track the airplane. He was told that the agency did not give information out to people over the telephone.
The intern ended his call by saying: "It's no big deal."
The plane had actually gone down about 9:40 p.m., but a search was not launched until a Kennedy family friend made a more urgent call to the Coast Guard at 2:15 a.m.
The FAA will not provide flight information about private citizens over the telephone, a spokesman said, and the Connecticut station acted appropriately.
Federal officials said that the plane's previous owner had installed a manual cockpit recorder, which could give investigators insight into the cause of the crash and possibly the last radio transmissions from the cockpit.
The recorder is connected to the plane's intercom system. Because a Piper Saratoga II generates a lot of noise in the cockpit, the passengers and pilots often wear headsets and microphones to communicate with each other. If the system was activated, and if everyone was wearing headsets, the last five minutes prior to the crash could have been recorded, a source close to the investigation said.
Kennedy family friends, who requested anonymity, said arrangements for a memorial service were being discussed. The service, they said, probably would be in New York, where the victims lived, and would not be held before Friday.
Hundreds of mourners continued to visit the John F. Kennedy Library and Museum in Boston, where a book of condolences was placed in the lobby. Some brought flowers. Others cried.
"You will be sadly missed," wrote David Zimmerman of Athens, Ohio.
Times staff writer Miles Corwin in Los Angeles contributed to this story.
Updates, additional photos and video related to the search for John F. Kennedy Jr.'s plane are available on The Times' Web site: http://www.latimes.com/kennedy