PORT HUENEME, Calif. - The pilots of Alaska Airlines Flight 261 struggled with a sudden control problem for at least six minutes before the jetliner plummeted into the ocean with 88 people aboard, federal investigators said Tuesday.
The last minutes of the MD-83's flight Monday may have been witnessed by pilots aboard four other aircraft, and the National Transportation Safety Board was seeking to interview them.
The plane plunged from 17,000 feet and crashed nose-down in the Pacific after the pilot reported problems with the horizontal stabilizer, a wing-like structure on the tail that controls the pitch of the aircraft's nose.
Investigators at the crash site also said Tuesday they had heard a pinging from the ocean, apparently from the flight recorders, which could reveal exactly what went wrong with the stabilizer.
The search was concentrated on a debris field about 10 miles offshore and about 40 miles northwest of the Los Angeles airport. Coast Guard, Navy and private vessels were joined by military airplanes.
Nearly a day after the accident, searchers had pulled four bodies - one man, two women and an infant- from the calm sea, which is 300 to 750 feet deep in the area. Hopes dimmed that anyone aboard Flight 261 survived in the 58-degree water.
''This is still a search for human life,'' Coast Guard Adm. Tom Collins said. ''The challenge is time. As time ticks off, risks go up.''
On shore in Port Hueneme, passers-by paused to bow their heads in prayer.
''It just feels so good to stand out here and pray. It sort of cleanses you out,'' said Diane Adame, 39. ''You don't realize when you put someone on a plane and give them a hug that you might not see them again. I just feel for the people who lost their loved ones, especially the young ones. I guess that's what really got me.''
The flight had left Puerto Vallarta, Mexico, for San Francisco and Seattle with 83 passengers and five crew members. The passengers included three airline employees, four employees of its sister airline Horizon and 23 relatives or friends of the employees taking advantage of free standby flights.
NTSB member John Hammerschmidt released preliminary transcripts of air traffic control communications with the airliner. The last routine transmission came at 3:55 p.m. PST, when the flight was cleared to continue to San Francisco.
At 4:10 p.m. the pilots said they had control difficulties and were descending below 26,000 feet. A few seconds later they advised they were at 23,700 feet and there was ''some discussion about their ability to control the aircraft,'' Hammerschmidt said.
Over the next few minutes, the pilots said they ''were kind of stabilized and going to do some troubleshooting,'' but then said they had a jammed stabilizer. At 4:16 they were cleared for an emergency landing in Los Angeles.
The controllers cleared the plane to 17,000 feet. The crew acknowledged that in what was the last known transmission from Flight 261, Hammerschmidt said. At 4:21 p.m. the aircraft dropped from radar.
The underwater pinging was pinpointed by a Navy team that joined in the search effort. Investigators were uncertain whether the pings were from one or both of the recorders.
One some planes, the horizontal stabilizer is monitored by the plane's data recorder. The other ''black box'' records pilot conversations.
If the data recorder was programmed to monitor the stabilizer, it would reveal the condition of the device's electrical and hydraulic controls. If not, officials would have to deduce what happened to the device by studying how other systems performed before the crash, said Barry Schiff, an aviation consultant and former TWA pilot.
The stabilizer typically is controlled by the automatic pilot, but can also be manipulated in the cockpit. Pilots are trained extensively in what to do about stabilizer malfunctions. If the problem can't be fixed, the nose of the aircraft can move up or down uncontrollably until gravity forces the plane into a dive.
Both pilots were Alaska Airlines veterans. Capt. Ted Thompson, 53, was hired in 1982 and had 10,400 flying hours with the company. First Officer William Tansky, 57, was hired in 1985 and had 8,047 flying hours with the Seattle-based airline.
''We want to make sure everyone knows that it would make my dad happy to see how many people saw him as a father, a brother and a friend,'' said Fred Thompson, 24, the pilot's son. ''And our hearts and thoughts are with the families of the Alaska employees and passengers.''
The investigation was being directed by a 10-member NTSB team that arrived in Port Hueneme early Tuesday.
Hammerschmidt said the NTSB would be interviewing as many as four pilots who might have seen Flight 261's final minutes from their planes - a Skywest flight, a private aircraft, another Alaska Airlines jet and a fourth plane that was not identified.
As search boats moved in and out of Port Hueneme, an artist erected a 7-foot wooden cross as a memorial to the victims. The cross was adorned with flowers, and a white plastic angel sat at the base next to a candle in a jar.
Victoria Arjaev, 55, of Port Hueneme, and her sister JoAnne Frank, visiting from Wisconsin, tossed a bouquet of red carnations into the water off the pier.
''We're going to say a prayer that they're in God's hands. And maybe for a miracle, that there's some survivor out there. You never know,'' Arjaev said.
Alaska Airlines, which has the image of an Eskimo painted on the tails of its planes, serves more than 40 cities in Alaska, Canada, Mexico and five Western states. Until Monday, the airline had gone 24 years without a fatal accident.
In the past year, Alaska Airlines has been the subject of federal grand jury investigation in Oakland over maintenance and repair records for some MD-80s.
A Federal Aviation Administration report concluded that records were falsified on two MD-80s that made 840 flights in late 1998 and early 1999. Because of the altered records, the aircraft were considered ''unairworthy,'' FAA documents said.
John Kelly, chairman and chief executive of Alaska Airlines, said the plane that crashed was not one of those involved in the investigation. An airline spokesman said the investigation focused on record keeping, not the safety of the airplanes.
Federal prosecutors declined to comment, citing grand jury secrecy rules.
The FAA had 44 reports of ''service difficulty'' for the plane that crashed dating to 1992, when it was built, but most deal with problems involving emergency lights and sliding windows not opening. In 1995, an engine failed and the plane landed without incident. The engine was replaced.
Jack Evans, an airline spokesman, said the plane had no previous stabilizer problems. The plane was serviced on Sunday, went through a maintenance check Jan. 11 and had a more thorough routine check a year ago, he said.