The skies were clear and visibility was excellent. Surface to air missiles have solid fuel rocket motors that leave a very visible smoke trail. Someone, most probably an airline pilot waiting to take off, would've seen a missile had there been one.

Sabotage can't be ruled out at this point and neither can a pure mechanical malfunction. For that matter, we can't rule out bird injestion, either. There were reports of a lot of birds in the area yesterday. Birds have brought down planes before.

According to this BBC article,

"There have been documented malfunctions involving General Electric's CF6 engines - the same model as that of the American Airlines flight - in the past.

Just last month, the FAA called for tougher inspections of possibly worn parts, saying they constituted an "unsafe condition" that could damage an airplane.

The FAA set a 60-day period for industry feedback, which was to end on 4 December.

The NTSB had also warned that failure of these engines during flight could send hot metal fragments tearing through important control systems or fuel lines, and could cause a plane to crash."

The right engine had over 9,700 flying hours on it, so the possibility of worn parts exists. There was an interesting tidbit of info in that article. It seems that particular A-300 lacks the ability to dump fuel in an emergency. That means the report from yesterday was incorrect. Perhaps there was fuel leaking from ruptured lines but the crew never had the option to lighten the plane by dumping.

According to this ABC News article,

"Officials said they had no reason to believe the incident was the result of a terrorist act, although FBI investigators will also participate in the probe. The cockpit voice recorder, one of the two 'black boxes,' already has been found and officials have begun to analyze it for problems.

'There is nothing on the tape that would lead us to believe it was anything other than an aviation accident,' George Black of the NTSB said today on Good Morning America.

There were no voices other than the pilots' on the tape, on no sounds that would indicate anything other than an accident, Black said."