The flight of John F. Kennedy Jr., his wife and sister-in-law was normal until about 17 miles from the airport off Martha's Vineyard, when the plane suddenly lost altitude in an apparent "graveyard spiral," an indication that pilot error was the most likely cause of the crash, air safety experts said Monday.
The plane lost 1,100 feet in only 14 seconds--a descent rate of 4,700 feet per minute--before it disappeared from radar coverage, National Transportation Safety Board officials said.
Experts said the high-performance Piper Saratoga that Kennedy was piloting generally cannot handle a descent much more than 1,500 feet per minute. The plane's gauge shows a maximum of 2,000 feet per minute. While in-flight breakup remains a possible reason for the crash, flight experts said the most probable explanation is some piloting error by Kennedy.
This type of accident often indicates the pilot lost control of a plane because of disorientation or vertigo, said Barry Schiff, a retired TWA pilot who is now an air safety consultant.
Because Kennedy was flying on a hazy night over water, with few visual reference points, he could have become disoriented. Kennedy was not trained to use flight instruments, so he could have dropped into a nose dive without realizing it.
"Structural failure is very unlikely, given the smooth weather and the newness of the plane," Schiff said. "The most likely explanation would be his losing control of the aircraft because of his lack of experience and qualification in a situation where there is no visible horizon. . . . He would become disoriented. The plane would begin to turn without his recognizing it or being able to take corrective action. This would lead to a graveyard spiral."
However, NTSB officials at a news conference Monday were reluctant to characterize the drop in altitude as unusual.
Kennedy attended a flight school in Florida and received his medical clearance--which allowed him to fly solo--in December 1997. He received his pilot's license four months later.
More debris from the plane washed onshore Monday at Martha's Vineyard and on some smaller islands nearby.
"There were numerous small pieces of the airplane found," said Robert Pearce, an NTSB investigator. "It was primarily pieces of the interior cabin, including molding, carpeting and cushions."
The Rude, a National Oceanic and Atmospheric Administration research vessel with side-scan sonar, has zeroed in on 10 possible targets for the crash site. Ten divers from the Massachusetts State Police operating off two boats will try to determine whether the objects spotted by sonar in 80 feet of water are, in fact, the main wreckage of the single-engine plane piloted by Kennedy.
Meanwhile, land crews operating on foot and atop all-terrain vehicles on Monday shifted their focus several miles down the beaches from the area around Gay Head lighthouse, where debris from the plane washed ashore. The debris was transported to a hangar at nearby Otis Air National Guard Base, where it will be examined.
Unlike commercial airliners, small, single-engine planes like Kennedy's Piper Saratoga are not equipped with "black boxes," which record cockpit sounds, or flight data recorders, which provide information on the plane's altitude, heading and readings of various instruments. But, Pearce said, preliminary information indicates the plane's previous owner installed a manual cockpit recorder. If the recorder is found, it could give investigators insight into the cause of the crash and possibly the last radio transmissions from the cockpit.
Investigators are studying weather data and interviewing witnesses in New Jersey--where the plane took off--and on Martha's Vineyard. They also are talking to flight instructors and anyone else who may have flown with Kennedy in an effort to learn more about his piloting skills.
Investigators have studied the plane's maintenance records, which were up to date. The plane was last inspected June 28.
Kennedy had planned to fly to Massachusetts early Friday evening, his friends told authorities. The departure was delayed, however, because of rush-hour traffic in New York and his sister-in-law's work commitments.
The plane took off from the Essex County Airport in Fairfield, N.J., at 8:38 p.m., federal officials said. The flight path took the plane through hazy skies along the southern coast of Connecticut at 5,600 feet.
At 9:26 p.m., Kennedy was off Westerly, R.I., and began to head over the water directly to Martha's Vineyard. There was a gap in the first radar tapes reviewed by investigators, but Kennedy's plane was again detected at about 9:38 p.m. about 17 to 18 miles west of the airport, flying at about 2,200 feet.
During the next 14 seconds, the plane plunged to 1,100 feet, where it left the radar scope.
The Kennedys on Monday issued their first public statement about the tragedy, saying that the family was filled with "unspeakable grief and sadness" over the death of John F. Kennedy Jr., his wife and her sister Lauren.
"He was a devoted husband to Carolyn, a loving brother to Caroline, an amazing uncle to her children, a close and dear friend to his cousins and a beloved nephew to my sisters and me," said the written statement released by his uncle, Sen. Edward M. Kennedy (D-Mass.). "He was the adored son of two proud parents whom he now joins with God. We loved him deeply, and his loss leaves an enormous void in all our lives.
"John had many gifts and gave us great joy, most especially when he brought his wonderful bride Carolyn into our lives. They had their own special brand of magic that touched everyone who knew and loved them. We are thankful for her life and for their lives together."
At dusk, the flag outside the Kennedy compound in Hyannis Port was lowered to half-staff.
The parents of Kennedy's wife, Carolyn Bessette Kennedy, and her sister, Lauren Bessette, issued a statement read by family friend Grant Stinchfield:
"Dr. and Mrs. Richard Freeman and William J. Bessette would like to thank the many individuals and governmental agencies that have assisted in the exhaustive search for their beloved family members.
"Each of these three young people--Lauren Bessette, Carolyn Bessette Kennedy and John F. Kennedy Jr.--was the embodiment of love, accomplishment and passion for life. John and Carolyn were true soul mates, and we hope to honor them in death in the simple manner in which they chose to live their lives.
"We take solace in the thought that together they will comfort Lauren for eternity. We are especially appreciative of the privacy and support provided us by our friends and family and community. Nothing in life is preparation for the loss of a child," the statement said.
A somber President Clinton on Monday also said that the loss was a very difficult thing for his own family, noting that "John Kennedy and his sister and later his wife were uncommonly kind to my daughter and to my wife."
Clinton spoke with Sen. Kennedy, with John Kennedy's sister, Caroline Kennedy Schlossberg; and with the parents of Lauren Bessette and Carolyn Bessette Kennedy.
"They are very strong people, and I think they are carrying on as well as any human beings could, but they need the support and prayers of our country," Clinton said.
Mourners continued to leave flower bouquets, notes and candles on the steps of the John F. Kennedy Library and Museum in Boston and on the steps of John and Carolyn Kennedy's apartment building in New York City.
Times staff writers Miles Corwin in Los Angeles and Paul Lieberman in Martha's Vineyard also 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
* FUTURE FOR KENNEDY'S MAG? George will try to find its footing with loss of its leader. C5
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The recovery effort is being aided by several high-tech ships, including the Rude and the Whiting, both National Oceanic and Atmospheric Administration search vessels. These ships locate wreckage by scanning the ocean floor using sonar and then analyzing the data so charts and topographic maps can be made.