Officials in the US said they were treating the American Airlines crash in New York as an accident rather than an act of sabotage.
But they warned that the investigation was just beginning and said it was too soon to rule anything out.
The whole air traffic system on the eastern US seaboard went into a heightened state of alert shortly after the crash, at 9.17am local time, but the initial sense of alarm subsided as aviation and government officials began to piece together the plane's final moments.
Marion Blakey, chairwoman of the National Transportation Safety Board, the government agency leading the investigation, said: "All information that we currently have is that this is an accident."
Speaking about five hours after the crash, she said the plane's flight data recorder had been recovered from the crash site in Rockaway, in the New York borough of Queens, and was being analysed by the board's investigators.
The four airports in the New York area, which were closed in the immediate aftermath of the crash, were all slowly reopening last night. There was no rush to check other aircraft awaiting take-off. In an initial review of recent intelligence communications, the Federal Bureau of Investigation found no evidence of a credible threat or any concrete indication that a deliberate attack was being planned. And the White House announced that President George Bush was going ahead with his schedule as planned, including a weekend trip to his ranch in Texas.
Officials nevertheless voiced caution, saying that in the post-11 September world it was especially important not to jump to conclusions. The White House spokesman, Ari Fleischer, told reporters: "We have not ruled anything in, and we have not ruled anything out."
Mr Fleischer stressed that all his information was based on initial reports. "And first information is always subject to change," he added.
American Airlines, which lost two jets in the attacks on New York and Washington two months ago, was even more tight-lipped. "We have absolutely no indication of what caused the accident," the company's chairman and chief executive, Donald Carty, told reporters at corporate headquarters in Houston.
Accounts by witnesses, both from New Yorkers who saw the crash from the ground and from other pilots and passengers on planes in the area, provided an initial – but very possibly distorted – impression of what happened.
The plane, an Airbus A-300, took off about half an hour late from John F Kennedy airport en route to Santo Domingo.
There were no unusual communications between the cockpit and air traffic control, according to US government officials, suggesting that the plane got into trouble extremely quickly. Shortly before the crash, a pilot on another plane and a passenger on a third plane saw a plume of smoke emanating from one of the doomed plane's wings.
There was then some kind of fire or explosion, and AA flight 587 plummeted towards the ground, its left-side engine detaching from the fuselage before impact.
Some witnesses on the ground reported seeing a flash – possibly consistent with an explosion – near where the wing and the main body of the aircraft are joined. Jackie Power, a Brooklyn resident who was out enjoying the late autumn sunshine with her husband, told ABC News she thought the flash could have come from the cabin or the baggage hold.
She said: "There was what looked liked fire or an explosion and debris fell from that side of the plane and it just plummeted and we heard this enormous crash." Aviation experts said it was impossible to tell from such reports whether the flash was the result of mechanical failure or sabotage.
One investigative team from the National Transport Safety Board was already on the ground, with another team en route. At the White House, Mr Bush hurried to the Situation Room and immediately set up a conference call involving the Attorney General, John Ashcroft; the recently appointed Homeland Security chief, Tom Ridge; New York's Mayor, Rudolph Giuliani; the New York state governor, George Pataki; the Transportation Secretary, Norman Mineta; the Federal Aviation Authority, the Federal Emergency Management Agency and military officials.
Shortly after the conference call, however, the President resumed his previously arranged schedule of meetings with world leaders, suggesting that initial fears of another terror attack had subsided.
If terrorism is ruled out, attention will surely turn to the plane itself. The A-300 has been involved in controversies about crashes in the past, with some critics claiming that something is inherently wrong with the plane's design – a charge that has never been borne out by official crash investigations or by statistical breakdowns of the number of airline crashes by model or make.
Airbus introduced the A-300 32 years ago, the first large passenger jet to be constructed with just two engines. There have been five other crashes since 1988, when the US warship Vincennes shot down an IranAir A-300 over the Gulf. The four subsequent accidents – two on China Airlines, one on the airline Garuda Indonesia, and one on the Pakistani carrier PIA – all occurred on the approach to landing, not on take-off. In this case, a mechanical failure would also focus attention on the engine. The US manufacturer General Electric confirmed that the plane was fitted with its CF6-model engines, in production since 1984. The company, which has a strong reputation for reliability, could not immediately say when the engines in question were made.
Airbus refused to make any initial comment on the crash, saying that it was waiting to find out more before making a public statement. The company said, however, that it would be offering all assistance to the crash investigators.
The New York area has been particularly prone to airline disasters, in part because it is one of the busiest air corridors in the world. The most recent major accidents – the crash of an EgyptAir plane in 1999, apparently the work of a suicidal co-pilot; the crash of a Swissair flight in 1998, and the 1996 crash of a TWA flight during the Olympic Games in Atlanta – have given rise to theories of a mysterious disaster zone in the American north-east.
Each of these crashes, however, has been found to have a different cause. The most suspicious of them, the TWA crash, was eventually deemed to have been caused by an explosion in a fuel tank, despite initial suspicions that it might have been downed by a missile.Reuse content