Recorded conversations by pilots on a freight jet with packages for Amazon.com Inc. who crashed at Houston last month, reveal that they lost control of the aircraft about 18 seconds before it hit the shallow bay, the researchers said Tuesday.
The communication recorded on the cockpit sound recorder was "consistent with a loss of control over the aircraft," according to a press release from the National Transportation Safety Board. The NTSB has restored the crash-proof cockpit recorder and another black box with flight data from the past few days and brought it to the lab in Washington for analysis.
The press release, which gives a first impression of what happened on the Boeing Co. 767-300 while getting ready to land at Houston's George Bush Intercontinental Airport on February 23, still does not explain the mysterious, abrupt dive. The second recorder contained detailed data of the flight from the accident as well as 16 earlier, but none of its contents were revealed in the NTSB statement.
Atlas Air Flight 3591 dived about 6,000 feet (1,829 meters) and plunged into a shallow bay as it descended and prepared to advance a series of storms. The impact broke the plane and killed all three on board: two Atlas pilots and one from a regional airline that was making a ride. There was no emergency call from the cockpit.
Atlas was one of three cargo carriers carrying a fleet of 50 aircraft for Amazon, according to a press release from the online retailer in December. Atlas is owned by Atlas Air Worldwide Holdings Inc.
A video taken from a prison about a mile from the crash showed the last five seconds of the plane before it hit the water, said NBSB chairman Robert Sumwalt in a briefing 24 February. The plane was in a "steep descent, steep nose down" posture "and there was no evidence that the pilots were trying to" turn around or pull up at the last moments, "Sumwalt said.
A separate video from a nearby school showed that the plane apparently dives into a cloud bank, according to the Houston Chronicle.
The cockpit recorder is about two hours long, but the sound quality is "bad", said the NTSB. "There are times during the recording when the content of the discussion about the crew is difficult to determine", according to the press release. "At other times, content can be determined using advanced audio filtering."
The NTSB convenes a group of experts to evaluate the content of the recorder and produce a transcription, the agency said in its release. "It will be a time-consuming process to complete the transcript," the agency said.
The aircraft was at a height of about 6,200 feet when pilots first discussed the unspecified control problem, according to a flight plot provided by tracker FlightRadar24. Around that time it climbed a few seconds and then began to decline, according to the website.
It went from 5,850 to 1,325 feet, the last position recorded by the website, in about nine seconds, which is many times faster than a normal fall speed.
Pilots were in conversation with air traffic controllers and were led to the airport, the NTSB said. The normal route to the airport was adjusted so that they could fly thunderstorms, according to a recording published by the website LiveATC.net.
The plane's data recorder recorded about 350 parameters, which usually contained information about the health of the engines and other aircraft systems, details about the route and speed, and indications of levers and switches activated in the cockpit. Researchers are busy validating the data and are planning to release more information within a few days.
The 767 family of jetliners, which was introduced in 1982, has a solid safety record. There were only two fatal accidents on the plane up to and including 2017, according to Boeing's annual summary of aviation safety.
Copyright 2019 Bloomberg.
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