March 5 (UPI) -- A preliminary analysis of the voice recorder data from a cargo plane that crashed last month indicates the pilots lost control of the Boeing 767 18 seconds before going down in marshland near Houston, the National Transportation Safety Board said Tuesday.
Investigators recovered the cockpit voice recorder Friday and have been reviewing the audio recordings, which the NTSB described as "poor."
"There are times during the recording when the content of crew discussion is difficult to determine, at other times the content can be determined using advanced audio filtering," the NTSB said in a report.
The agency said the data indicated crew members communicated with air traffic control in Houston to prepare for landing. Those communications indicated the loss of control lasted for about 18 seconds before the end of the recording.
On Sunday, investigators recovered the flight data recorder, which they disassembled, cleaned and dried before downloading the data. The recorder had 54 hours of data, including about 350 parameters detailing the motion of the airplane and the operations of its systems.
Atlas Air Flight 3591 was operating for Amazon Prime Air on a flight from Miami to Houston.