John Nance, an aviation analyst and veteran airline captain, said that if controllers knew the plane's altitude during its drop, it would indicate the jet still had partial electrical power. While radar locates a target in the sky, controllers do not know the identity of the blip or its altitude without information broadcast from the airplane's transponder. That broadcast can only be made with the help of electricity supplied by the plane. A continuing electrical supply could help the investigation because it could mean the electric-powered flight data recorder and cockpit voice recorder kept operating during part of the descent. The TWA plane blew up off Long Island, N.Y., in July 1996, killing all 230 aboard.
Investigators believe the plane's nearly empty center fuel tank exploded.
A bomb destroyed Pan Am Flight 103 over Lockerbie, Scotland, in December 1988, killing 270 people on board and on the ground. Investigators were also looking at the plane's production and maintenance history. The plane, tail number SU-GAP, was delivered to EgyptAir in September 1989, Hall said. All Rights Reserved.