Subscribe to one of our news e-mail lists. As U.S. Navy salvage ships sailed toward the crash site of EgyptAir Flight 990 in the hope that calmer seas Friday would allow recovery efforts, new radar data indicated the jet's engines were still operating as the plane plunged toward the ocean about 60 miles south of Nantucket . K CNN's Mike Boettcher looks at thrust reversers and how they might cause a plane to crash. 28K 80K Use the arrow buttons below to scroll through the video gallery. If the plane was flying straight downward, it would have traveled at more than 400 mph.
Investigators know that the plane was also traveling forward.
Therefore, its speed would have been even higher. The data, released Thursday by Megadata Corp., adds significantly to what is known about the final moments before Sunday's crash which claimed the lives of 217 passengers and crew. The Megadata Corp. data show that the plane's top rate of descent was 39,100 feet per minute, or more than 444 mph if it had been traveling straight down. Its peak speed was reached as the plane dropped from 30,600 feet to 24,600 feet. An aviation expert told CNN the Megadata readings show the rate of acceleration was greatest as the plane pitched over and began its descent.