Monday, November 1, 1999 Published at 12:24 GMT
EgyptAir 990: The search for clues
A 767-300 similar to the one which crashed
The investigation into the EgyptAir flight 990 crash is still officially a search and rescue mission, but aviation safety experts say it is doubtful that any survivors from the missing flight will be found.
Within minutes of the flight vanishing from air traffic control radar, a meticulously-planned operation swung into action.
But investigators are already saying it could be many months before the cause of the crash can be established.
In a blow to the plane's manufacturers, Boeing, it has emerged that the EgyptAir 767 came off the assembly line shortly before another 767 liner that crashed eight years ago, killing all 217 people on board.
But a company spokesman stressed that they had no indications that the two crashes were related.
Within hours of the EgyptAir crash, a team of Boeing experts arrived in Nantucket to assist in the investigations.
The Egyptian Government is officially responsible for the crash investigation, as it was an Egyptian plane that crashed in international waters.
But it has asked the NTSB to carry out the inquiry, co-ordinating search, rescue, recovery and investigation.
The investigators will follow an established pattern, BBC US affairs analyst Jonathan Marcus says.
First, they will try to find the plane's voice and data recorders to obtain vital clues to the flight's final moments.
Then the arduous search for parts from the wreck will begin - the investigators will aim to retrieve as many parts as possible.
If necessary, our correspondent says, the aircraft will be reconstructed piece by piece in an effort to find the cause of the crash.
Debris was found inside a 36sq mile area that will become the focus of attention for the coming days' searches.
USS Grapple, which assisted in the search for John F Kennedy Jnr's plane, will be involved again.
It has on board sophisticated sonar equipment that will speed up the hunt for debris.
Specialised search vessels from the National Oceanographic and Atmospheric Administration are also being deployed.
Sonar maps of the seabed and remote-controlled vehicles will help divers recover debris.
The remotely-operated vehicles, with grapple hooks, are expected to be used to pile up debris in one place on the seabed.
Divers will transfer that debris into salvage baskets and bring it to the surface.
But, working at depths of up to 75 metres (250ft), the divers' time under water will be limited to about 40 minutes at most.
On the surface, large numbers of support staff will be on hand to ensure the divers are safe and that the whole search is co-ordinated.
Despite the inherent dangers of the work involved, it will also be a race against time.
The approaching winter in New England can bring swelling seas which would at best make the recovery more difficult. At worst, it could stop it in its tracks.
Wreckage brought up from the seabed is expected to be taken to Providence, Rhode Island, where it will be stored until the investigation is complete.
Most experts rule out sabotage or a terrorist attack as the cause of the crash.
Security on EgyptAir flights is among the tightest in the world, with armed security guards routinely on board. After the airline's passengers go through the normal airport security check, they are again subjected to baggage search just before they board the aircraft.
A spokesman for the Federal Bureau of Investigation, Jim Davis, said: "We have no threats, we have no-one claiming responsibility."
Searching for a fault
Another possible explanation could be fault in the plane's systems, for example an explosion in the fuel tanks.
Some people have suggested that this was the cause of the crash of a TWA jumbo jet in July 1996. However, air safety experts have not yet come up with a comprehensive explanation.
The EgyptAir plane was an identical model to the Lauda Air plane that crashed in Thailand during take-off in 1991.
Both were 767-300ERs with extra fuel capacity for long-range flights.
The wreckage from the Lauda Air crash suggested that one of its engine thrust reversers deployed in flight, sending it into an uncontrollable dive.
After the crash, airlines were ordered to install an extra locking system on a wide range of Boeing aircraft.
A Boeing spokesman, though, has warned that it is far too early to say what caused the EgyptAir crash.
"At this point, there is absolutely nothing known about the cause, but we'll help in any way we can," Boeing spokesman Russ Young said.
The Boeing 767 is the "workhorse" on transatlantic routes for many airlines.
It was introduced as a passenger airliner in 1982 and has not had an unusually high accident rate.