At the time when the AA 587 crash occured I considered starting up a thread about the complete inconsistency between the reports of explosions that came from the eye witnesses and the evidence from the missing tail that the crash had an aerodynamic origin. It seemed to me that this horrible accident provides a vivid demonstration of the lack of reliability of eye witness evidence of air crashes. I never got around to starting up that thread.
While the eye witnesses themselves may be sober characters with solid backgrounds in the police and fire services, the question that must be asked is why were they looking at that particular aircraft at that particular time?
Living in that part of New York, they must have an aircraft flying overhead from JFK every 90 seconds or so, day after day after day. People living under very busy flightpaths just do not look up at the planes flying overhead -- they ignore them.
For these citizens to have looked up at the plane, there must have been something that had already happened to it to make it different from the hundreds of other overflying planes. Whether it was a flash of light, or the sounds of igniting fuel, airframe breakup, or changed engine noise, something must have already occured to the plane before they glanced up.
It follows that we should view with some scepticism their claims that the crash was directly caused by any "explosion" that they witnessed. Such an "explosion" was likely secondary to the primary cause of the crash, that primary incident being the stimulus for the witnesses to begin looking at the plane in the first place.