These are frames from an FAA radar tape obtained by Paris Match and published at their website and in their newspaper.
These images say it all. (separate the GIF into frames to study)
00 h 29 min 58 s:
According to Paris Match, the object in the red circle is the US Air flight, descending into Rhode Island which is going to intersect the flight path of the TWA flight and force it to take an air corridor that is unusually low. I qualify the identification as there is no associated data block within the field of view of this image. Flight 800 is in the blue box, and although the slash through the zeros makes it hard to read the numbers, the course annotation "BET - 37 H" is the assigned course for flight 800. The "H" means "Heavy", the ATC designation for a wide body jumbo jet.
00 h 30 min 17 s:
Circled in yellow, the US Navy P-3 Orion which refuses to identify itself. It will stay on the scene until one minute after the explosion. The aircraft in the Red Circle is on a northerly course headed into Rhode Island, consistant with the prior identification as the US Air flight.
00 h 30 min 35 s:
In the green circle emerges what the J.F.K. experts call an "anomaly" and which Paris Match thinks might well be the target missile whose course is carefully chartered by the P-3 Orion. My own concern about this object is that it appears mid-screen, well away from any visible launching platform. The U.S.S. Normandy is away to the Southwest, and the Standard Missile could not transit the radar view to appear within the green circle without being caught by earler sweeps. Since there was a submarine in the area exercising with the P-3, it's possible that the object in the green circle was a sub launched SAM undergoing tests.
00 h 30 min 42 s:
The "anomaly" still appears on the screen. It will stay on the radar screen for precisely twelve seconds, "being hit" by a radar sweep every four seconds for a total of four successive "hits". The successive sweeps rule out noise, which would plot as random dots all over the screen. Bradband noise able to get past the radar filters would appear as wide area blotches, not a dot. Compare the position of the "anomaly" in this frame versus the position in the prior frame relative to Flight 800. It is clearly closing the 747 from behind, meaning that the anomaly is travling at supersonic speed.
00 h 30 min 44 s:
The "anomaly" has disappeared. The TWA 800 is flying at 13,300 feet. Still visible on the radar screen, the US Air flight (in the red circle) and the P-3 Orion (in the yellow circle).
00 h 31 min 16 s:
Last second before the explosion. Paris Match says that the LA/CA code onscreen indicates that everything is still going smoothly. I disagree. My understanding (and I'm double checking) is that the CA ALERT warns of a close approach.
00 h 33 min 12 s:
Two seconds have not gone by since the explosion. The alert still hasn't been given. J.F.K. is still trying to understand what has happened to the TWA 800. The radar picks up an unidentified aircraft (blue rectangle) in the immediate area around the crash.
00 h 34 min 02 s:
The air traffic controller calculates that this object is flying at just 200 feet (66 metres) - it must be a helicopter, the only craft able to fly so low. Note that the data block for Flight 800 has vanished from the screen.
00 h 34 min 52 s:
It is a helicopter. It identifies itself to the controller using the codename "Jolly", a popular code for military helicopters and inspired by the Jolly Green Giant, which came to the rescue of many GIs in Vietnam. Before anybody else, the US Navy is already on alert and aware of the crash.
00 h 34 min 52 s:
It is a helicopter. It identifies itself to the controller using the codename "Jolly", a popular code for military helicopters and inspired by the Jolly Green Giant, which came to the rescue of many GIs in Vietnam. Before anybody else, the US Navy is already on alert and aware of the crash.