Don't really have a good mental picture of it, and I'm not good at creating animations unfortunately. It's just based on what he's said in this interview (0:50-1:50):Sounds like you've got a good mental picture of the flight path. Could you create a motion graphic of it? GeoGebra perhaps. Could be useful for further discussion.
He first says that when they arrive they see it hovering above the water, it's about 40 ft and shaped like a tic tac:
Keep in mind he's recalling this from an event from 13 years ago though.
Actually, at around 2:40 he says that he could easily have seen an object that size up to 10 miles (us miles or nautical miles?) away and that it disappeared from view in two seconds. That would mean faster than about 8-9 km/s (about mach 25) which sounds extreme. On the other hand is it impossible they simply lost track of it? ... Maybe they were looking at the horizon when they should have been looking up, for example.
EDIT2: corrected the speed calculation in first edit.