PORT HUENEME, Calif. -- The Navy has been asked to search for a piece of Alaska Airlines Flight 261 that investigators believe may have broken off as the jetliner began its fatal plunge into the Pacific Ocean, the NTSB chief said Tuesday.
A loud noise heard on the cockpit voice recorder corresponds to radar signals as the MD-83 begins its final dive into the sea, Jim Hall, chairman of the National Transportation Safety Board, said in a briefing in Washington, D.C.
Radar showed what could be parts of the aircraft carried by the wind up to 2 1/2 minutes after the plane struck the water. The Navy will search an area four miles from the main wreckage where investigators believe any pieces might have landed, Hall said.
''These primary radar hits might be indicative -- and I emphasize might be indicative -- of something coming off flight 261 near this point,'' Hall said.
In other developments Tuesday:
n The Ventura County Medical Examiner's office released the names of two men and a woman whose bodies were recovered from the wreckage and said the release of a fourth victim's name was pending.
n Officials revealed that the MD-83 had two ''maintenance write-ups'' late last year for problems with its horizontal stabilizer, the wing-like piece of equipment on the jetliner's tail that is the focus of the crash investigation. In October, the trim system was checked and the plane returned to service. A month later, mechanics replaced its alternative trim switch. It was unknown what prompted the concerns, and Hall did not elaborate on the two service checks.
n The Navy Monday night recovered an eight-foot section of what is believed to be the left horizontal stabilizer and part of the center horizontal stabilizer.
n The NTSB described the final minutes of the flight, when the plane abruptly dropped 7,000 feet and leveled off before free-falling nearly 18,000 feet in one minute.
The Jan. 31 crash 10 miles off the coast of Ventura County killed all 88 aboard.
Analyzing the flight data recorder and cockpit voice recorder, investigators determined Flight 261 was cruising on autopilot at 31,000 feet 12 minutes before the crash.
The horizontal stabilizer, which controls the plane's up and down motion, moved to an apparent full ''nose-down'' position as the pilots simultaneously disengaged the autopilot, Hall said.
The plane dropped nearly 7,000 feet in one minute, more than three times the typical rate of descent, as the crew struggled to level it. They finally brought it under control at 24,300 feet and over the next nine minutes descended in what Hall described as a ''controlled flight'' to 18,000 feet.
''Things then began to happen very quickly,'' Hall said.
The plane nose-dived at a roughly 60-degree angle within three seconds, eventually reaching an acceleration of negative 3 Gs.
The standard force of gravity experienced by a person standing still is 1 G. Riding a modern roller coaster, a person would experience a sense of weightlessness at an acceleration of negative .25 to .5 Gs.
An MD-80-series jet is designed to be maneuverable up to a negative 1 G with flaps and slats on the wings retracted, said John Thom, a spokesman for Boeing Corp., which bought the plane's builder, McDonnell Douglas, in 1997.
''You're above the structural limitations of the airplane,'' said William Waldock, associate director for the Center for Aerospace Safety Education at Embry-Riddle Aeronautical University in Prescott, Ariz. ''In a way, I'm almost surprised the wings stayed on.''
As the plane nose-dived, it pitched to the left and inverted, corkscrewing from 17,900 feet to the ocean in just over a minute.
All victims appeared to have died instantly, said Ventura County Medical Examiner Ron O'Halloran.
''The impact was forceful, and it is extremely unlikely that anyone maintained consciousness or suffered beyond the impact,'' he said during a news conference in Ventura. He also released the identities of three passengers whose bodies were recovered: Harry Stasinos, 54, of Brier, Wash.; Meghann Hall, 19, of Enumclaw, Wash.; and Joseph Knight, 54, of Snohomish, Wash.
The office has five to 10 bodies described as mostly intact, but even those cannot be identified visually because of ''extensive trauma,'' he said. Examiners are using dental records and fingerprints.
O'Halloran said all identified remains will be returned to the families.
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