NEW YORK – Air crash investigators said turbulence caused by a jumbo jet in front of American Airlines Flight 587 may have caused the plane to break apart after takeoff and plummet to the ground in New York.
National Transportation Safety Board chairwoman Marion Blakey said the American Airlines Airbus A300 took off less than two minutes after the Japan Airlines Boeing 747 jumbo jet in front of it and investigators were looking into whether the "wake turbulence" from the JAL flight may have contributed to the inflight breakup of Flight 587.
"We do not know whether this contributed in any way to the actual accident, but we are looking at this very closely," said Blakey.
"Wake turbulence" has been blamed for deadly airline crashes in the past. Investigators want to know whether it caused Flight 587 to break apart three minutes after takeoff from Kennedy Airport on Monday, killing all 260 people aboard and as many as five on the ground. The plane's tail assembly sheared away and its twin engines fell off as the jet went down.
The standard minimum amount of time between flights taking off is two minutes. However, Blakey said it appeared there were less than two minutes between the takeoff of Flight 587 and a Japan Air Lines jet that left ahead of it from the same runway.
"We believe that in fact it was 1 minute and 45 seconds in terms of the actual distance," Blakey said.
Pointing to a map of the two planes' flight paths, Blakey noted that although the jumbo jet's path was 800 feet above Flight 587's, the winds probably pushed the turbulence lower.
The Federal Aviation Administration has set minimum distances for planes flying near each other, based on aircraft size. After a 1992 crash in Billings, Mont., that killed eight people, federal investigators found that the pilot failed to follow the established "vortex avoidance procedure" and flew too close to a jet.
Blakey also said that a flight data recorder recovered from the flight was repaired by the manufacturer, allowing investigators to extract data on the last minutes of the doomed flight. The black box recorder had been scorched and banged up in the crash.
The flight data recorder monitors nearly 200 separate functions in the European-made Airbus A300, including rudder movements.
The other black box from Flight 587 — the cockpit voice recorder — was found earlier. It revealed that the pilots began losing control of the plane within seconds of hearing two rattling noises. The pilots also mentioned hitting wake turbulence.
Walter Sheriff, a retired American Airlines captain who studies the phenomenon, said the wake turbulence from the four-engine 747 could have struck the Airbus A300 with "tornado-like lateral force."
Questions arose about the plane's tail fin, which was fished out of Jamaica Bay, a short distance from the crash site; the rudder was found nearby. The rudder, which is supported by the tail fin, controls the plane's turns from side to side.
"We'll be looking very carefully at how the tail failed," the NTSB's George Black Jr. said.
The 27-foot tail fin was ripped off the fuselage cleanly, as if it had been sliced by a knife. David Stempler, president of the Air Travelers Association, said he and several pilots he spoke to were struck by the sight.
"It's as if you had a model of an airplane and you just snapped the stabilizer off," he said. "It's really shocking and surprising."
Safety records show the same plane was severely shaken by air turbulence seven years ago in an episode that injured 47 people. An aviation consultant said the plane could have been weakened by the earlier encounter.
"I would expect that the airplane underwent inspection after the turbulence encounter to verify that it hadn't been damaged and any damage that was incurred was fixed," Jim McKenna said.
NTSB investigators are reviewing records, interviewing maintenance employees and asking questions about the 1994 incident.
Both of the plane's engines have been recovered and taken to a hangar at Kennedy.
Investigators said both engines were relatively intact, which seemed to discount early speculation that one of them blew apart and propelled pieces into the body of the plane. Investigators also cast doubt on the theory that birds had been sucked into the engines and brought the plane down.
Authorities have not ruled out sabotage or other causes but have said all signs point to a mechanical failure.
"That does not mean we have concluded there was no crime. We simply have no evidence to date of a crime of terrorism," Attorney General John Ashcroft said.
"This would be the most catastrophic inflight disaster we've ever had. We've never had a modern civilian jetliner come apart in flight. It is so unbelievably catastrophic what happened," former Transportation Department inspector general Mary Schiavo said.
The Associated Press contributed to this report.