A routine descent for an airliner would be about 1,500 to 2,000 feet per minute,said John Cox,the president of the consulting company Safety Operating Systems who has participated in numerous crash investigations.
The final data point obtained by FlightRadar24 showed the plane descending at 30,976 feet per minute,meaning it was moving downward at about 560 kilometres an hour. Such speeds are typical of mid-range flight speeds,but unheard of for a descent.
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"This thing really comes unglued,"Cox said."The numbers are barely believable."
FlightRadar24's track of the flight raises as many questions as it answers. It shows the plane rising and climbing repeatedly with the speed also varying,both of which aren't typical on the latest,computer-driven aircraft. Multiple failures involving the crew and equipment on the plane are possible explanations,from an erroneous speed indication to some sort of electronic failure.
Shortly after takeoff from Jakarta,one of the plane's pilots requested permission to return to the airport,indicating the crew may have been struggling with some type of failure.
The limited and sometimes contradictory information about the flight doesn't obviously match any previous accidents,making it difficult to narrow down the possible cause,said Steve Wallace,the former head of accident investigations at the US Federal Aviation Administration.