A review of flight-track data shows that the China Eastern Airlines jet was traveling at close to the speed of sound before it slammed into a hillside.
It can destroy evidence and damage the data and voice recorders that are designed to survive most crashes.
According to data from Flightradar 24, the Boeing Co. plane was flying at an average speed of more than 700 mph.
John Hansman, a professor at the Massachusetts Institute of Technology, said that the data indicated it was near the speed of sound.
Sound travels at 761 mph at sea level but slows as air temperature goes down and is about 663 mph at 10,668 feet.
According to data transmitted by the plane and captured by Flightradar 24, Flight 5735 was flying to Guangzhou from Kunming with 132 people on board at an altitude of about 29,000 feet. The jetliners was cruising at over 600 mph.
The speed data is consistent with the videos that show the jet diving at a steep angle in the moments before impact, which indicates that it hit the ground with a lot of force.
Bob Mann, president of R.W. Mann & Co., who did not participate in the speed analysis, said it was an exceedingly high-energy crash. Do the flight data recorder, cockpit voice recorder, and quick access recorder survive? I don't know the answer.
James Cash, the U.S. National Transportation Safety Board's chief technical adviser for recorders, said that modern black-box recorders have a good record of survival in high-velocity crashes.
The hard part is going to be finding it.
The circuit boards that hold the data break from the recorder's protective exterior. Even if the data is damaged, it can usually be recovered.
He said it was probably embedded in the ground.
The recorders have not been recovered, according to an official with the Civil Aviation Administration of China. Searchers won't be aided by a beacon orping from the devices because they are only activated underwater.
The cockpit voice recorder and flight data recorder were installed on the plane when it was new, according to a company spokesman.
Crash investigators have spent decades looking for clues, but some impacts can destroy evidence. According to a preliminary report from that nation, a sensor on the plane's nose was the cause of the crash, but it was not found after the plane hit the ground.
Accident investigators should be able to find more precise speed data from the jet's flight recorder. If it isn't available for some reason, aerodynamic experts can perform extensive analysis to more closely estimate speed.
The jet's speed is measured across the ground. The computations give a rough idea of how fast it was flying through the air by taking into account its horizontal speed over the ground as well as how fast it was descending.
The speed estimates were based on how fast the jet traveled between points, but didn't take into account wind direction or other atmospheric conditions. The review was conservative and may have been higher.
It wasn't clear how fast the plane was traveling when it was shown in videos diving at a steep angle near the ground. The last data transmission took place at 3,200 feet altitude.
The jet stopped descending about 40 seconds before the last transmission. According to the preliminary review, it slowed down during the later stages of the flight.
It was still flying fast. Typically, jets don't go over 300 mph at altitudes below 10,000 feet. The China Eastern jet was traveling at over 500 mph at those altitudes.
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