or United Airlines Flight 811, but all evidence indicated that the door was closed and locked at impact. The NTSB concluded that "the in-flight breakup of TWA flight 800 was not initiated by a pre-existing condition resulting in a structural failure and decompression." Missile or bomb detonation A review of recorded data from long-range and airport surveillance radars revealed multiple contacts of airplanes or objects in TWA 800's vicinity at the time of the accident. None of these contacts intersected TWA 800's position at any time. Attention was drawn to data from the Islip, New York, ARTCC facility that showed three tracks in the vicinity of TWA 800 that did not appear in any of the other radar data. None of these sequences intersected TWA 800's position at any time, either. All the reviewed radar data showed no radar returns consistent with a missile or other projectile traveling toward TWA 800. The NTSB addressed allegations that the Islip radar data showed groups of military surface targets converging in a suspicious manner in an area around the accident, and that a 30-knot radar track, never identified and from the crash site, was involved in foul play, as evidenced by its failure to divert from its course and assist with the search and rescue operations. Military records examined by the NTSB showed no military surface vessels within of TWA 800 at the time of the accident. In addition, the records indicated that the closest area scheduled for military use, warning area W-387A/B, was south. The NTSB reviewed the 30-knot target track to try to determine why it did not divert from its course and proceed to the area where the TWA 800 wreckage had fallen. TWA 800 was behind the target, and with the likely forward-looking perspective of the target's occupant(s), the occupants would not have been in a position to observe the aircraft's breakup or subsequent explosions or fireball(s). Additionally, the occupants of the target track were unlikely to have been able to hear the explosions over the sound of its engines and the noise of the hull traveling through water, even more so if the occupants were in an enclosed bridge or cabin. Further, review of the Islip radar data for other similar summer days and nights in 1999 indicated that the 30-knot track was consistent with normal commercial fishing, recreational, and cargo vessel traffic. Trace amounts of explosive residue