After locating main parts of the wreckage of EgyptAir Flight 804, searchers have now found the airplane’s cockpit voice recorder, Egyptian officials say. Recovering and downloading the recorder’s data should be a major step in learning what caused the disaster. Data recording the speech and actions of the pilots is not as crucial to the investigation as the far richer data on the flight data recorder, but it is of urgent interest in this case because there is no record of any distress calls from the pilots.
The swift success of the search means that, for once, the technology designed to locate an airplane lost over an ocean actually worked.
The breakthrough in this case was being able to establish where the airplane went down with an accuracy as close as five square miles.
Two devices were key: an emergency locator transmitter, ELT, attached to the rear of the airplane itself, and a beacon with a short battery life attached to the flight data recorder. Both failed to work in the two most recent instances of airplanes that disappeared over oceans: Air France Flight 447 in 2009 and Malaysia Airlines Flight 370 in 2014.
The ELT is designed to automatically register impact with either water or land and then send half-second bursts every 50 seconds to a satellite. The information is then beamed from the satellite to a ground station where operators can establish the exact point where the transmitter is—although experts say it can take as long as a 100 minutes to obtain a totally accurate fix.
The beacon on the flight data recorder is a bigger challenge. The range of its signals is limited by the conditions of the ocean, influenced by both the depth at which it lies and the effect of water temperature and currents. At best, its signals can be picked up only at a maximum range of around a mile and a half. The batteries powering the beacon have a life of around only 30 days.
In this case the crew of a French naval vessel, the Laplace, seem to have done an amazing job. Following the lead of the ELT, they arrived at the indicated location and detected the signals from the flight data recorder’s beacon while there were still two weeks left of battery life—although once the location of the beacon was fixed, the battery life did not matter any more.
The Laplace then had to wait in place for the arrival of the John Lethbridge, a ship equipped with a remotely operated underwater vehicle, ROV, that was able to go down to the extreme depths where the wreck is believed to be, as deep as 10,000 feet, and send back sonar images.
All these steps would appear to have been achieved with textbook speed. The next priority will be to establish where the rear fuselage of the Airbus A320 might be. That is where the flight data recorder, the black box, is located and recovering that recorder—and the cockpit voice recorder—mechanically from the wreck will be a demanding test. It is highly probable that the data on the recorders will be retrievable. The recorders from Flight 447 were found at a depth of 13,000 feet after two years and French investigators were able to download a complete record of what happened.
Experts with long experience of similar searches have been puzzled by the absence of any floating wreckage of significant size. In the cases of Air France 447 and Malaysia Airlines Flight 370 identifiable pieces of the airplanes were found floating—albeit in the case of the Malaysian Boeing 777, turning up only after more than two years as flotsam on beaches.
The absence of significant pieces of the Egyptian A320’s structure turning up as floating debris suggests that most of the airplane is on the ocean bed. As the searchers now seek to retrieve the data recorders they will also be mapping the debris field, and that will give significant clues to the way the airplane broke up—which, in turn, may help to establish what caused it to suddenly plunge to its destruction from 36,000 feet.
At the moment there is no reliable indication of whether the crash was caused by a technical failure or by an act of terrorism. It is to be hoped that the same expertise shown in locating the wreck will prevail in the following investigation—the French accident investigation branch, the BEA, fields one of the most proficient and trusted teams in the world. If they are allowed to lead the investigation it will be reassuring to the airlines and world aviation authorities who have so far been troubled by the erratic and contradictory statements coming from Egyptian authorities.
It has never been clear how the Egyptians themselves assign the responsibility of conducting an air crash investigation. Normal international standards that guarantee the independence of investigators have not so far been evident under the current authoritarian regime. These include leaving the examination of wreckage to professional accident investigators and making no statements that cannot be supported by evidence.