- Specialist vessel found A320’s wreck in eastern Mediterranean
- Evidence from black boxes seen as key to explaining jet’s fate
Air-crash investigators said the cockpit voice recorder from EgyptAir Flight 804 has been retrieved from the eastern Mediterranean, four weeks after the jet disappeared from radar screens with 66 people on board.
The so-called black box, one of two on the aircraft, was damaged but its memory unit is intact, Egypt’s Ministry of Civil Aviation said in a statement Thursday. The recovery effort was led by the search vessel John Lethbridge, which had been drafted in to scour an area of seabed for the Airbus Group SE A320’s remains.
Finding the plane’s voice- and flight-data recorders has been viewed as an essential step in revealing why it crashed en route to Cairo from Paris on May 19. While pings from the black boxes were detected two weeks ago, the transmitters have battery power to last only until about June 24.
Egypt announced the retrieval of the recorder that captures pilot conversations and sounds from the cockpit less than a day after revealing that the debris field from Flight MS804 had been discovered, and that the area would be mapped to determine how best to deal with the wreckage.
Known as a cockpit voice recorder, the device may provide a number of clues about what caused the plane to stop transmitting its position and then begin a series of unusual turns before plummeting into the water. Pilots didn’t issue a distress call.
In addition to anything useful pilots may have said about what happened, there can be evidence from background sounds, according to previous accident files.
Recorders have been used to verify engine speeds and determine which switches pilots activated. Dutch investigators used a recorder aboard Malaysia Airlines Flight 17, which was struck by a missile on July 17, 2014, over Ukraine, to pinpoint the location where the warhead detonated. Cockpit recorders have four separate microphones and investigators were able to compare the slight differences between the time the concussion’s sound waves reached each one, according to the Dutch Safety Board.
At the same time, having only the cockpit recorder may not be enough to determine a cause, according to accident files. In the case of EgyptAir Flight 990, which crashed into the Atlantic Ocean on Oct. 31, 1999, the U.S. National Transportation Safety Board had to rely on both the cockpit recorder and a flight data recorder to conclude that a co-pilot intentionally downed the plane.
In that case, the pilot could be heard repeatedly saying “I rely on God” before the plane began an abrupt descent, but he never made any comments conclusively indicating his intentions.
The NTSB is sending two investigators to Cairo to assist the Egyptians in downloading data from the recorders, according to an e-mailed statement.
The plane’s data recorder -- which stores detailed records on a plane’s path as well as its mechanical systems and computers -- hasn’t been found yet.
The John Lethbridge, hired from Deep Ocean Search Ltd., carries scanning sonars and a remotely-operated vehicle equipped with high-resolution cameras that work at depths of as much as 6,000 meters (20,000 feet). The vessel can also be fitted with manipulator arms to aid salvage efforts.
The black-box pings were detected by the French Navy survey vessel Laplace using torpedo-shaped Detector 6000 listening systems from Paris-based search specialist Alcen, which are dragged beneath the ship and can “hear” signals from 5 kilometers (3 miles) away.
Previous attempts to find the jet with a submarine were hampered by an ill-defined search area and waters thought to be more than 3,000 meters deep.
While Egypt is leading the crash probe, the BEA, France’s air-accident investigator, is likely to play a key role in analyzing the flight recorders, given its expertise involving jets built by Toulouse-based Airbus. The NTSB also joined the investigation this month.
Experts remain unclear about what destroyed the A320. While human remains found earlier might indicate a catastrophic incident such as a bomb, bodies can be ripped apart when a jet suffers a structural failure, or hits the ground or sea.
A string of error messages sent automatically minutes before the A320 disappeared indicate that smoke had been detected beneath the cockpit and in a lavatory, and that windows next to the co-pilot’s seat may have malfunctioned, together with unspecified issues with flight computers.
While those readings might be explained in terms of a bomb blast, they could equally have resulted from a fire and associated electrical failure. Radar images suggest the plane also veered sharply left and then circled right before plunging into the sea.