French investigators have detected signals from the black box of the missing EgyptAir plane which crashed in the Mediterranean Sea last month.
Sixty-six people were on board Airbus A320, which took off in Paris and was en route to Cairo when it went off radars and plunged into the sea on May 19.
The passengers included 30 Egyptians, 15 French citizens, two Iraqis, two Canadians, and citizens from Algeria, Belgium, Britain, Chad, Portugal, Saudi Arabia and Sudan.
Seven crew and three security personnel were also on board the flight.
While authorities were quick to ascertain that the jet had in fact crashed, there were no signs of the wreckage for days and no pings from the black box – which remains intact even after the accident – needed to determine its location.
But 13 days after the incident the French investigation team finally made a breakthrough by using deep sea listening devices to pick up signals from the flight recorder on Wednesday.
Remi Jouty, an official from France's aviation safety agency BEA, told Agence France Presse: "The detection of this signal is a first step."
Responding to the development, Egypt's Ministry of Civil Aviation said the signals were "assumed to be from one of the data recorders."
Call to 'reinvent' the black box
Although wreckage from the plane has already been found in the Mediterranean Sea, the black box will help provide crucial information about the crash, which some experts believe may have been caused by terrorism.
Another vessel sent by Deep Ocean Search (DOS), a private company hired to help find the black boxes, is on its way to the area carrying a ship with a robot capable of diving up to 3,000 metres to retrieve the recorders.
The ship is due to arrive at the site within a week, the Egyptian ministry said.
Black box upgrade
The delay in detecting the black box has renewed debate about the efficiency of black boxes, which are capable of emitting signals for up to four weeks but usually sink to the bottom of the sea in the event of a crash in the ocean.
It has now been 816 days since Malaysian Airlines flight 370 disappeared somewhere over the Gulf of Thailand.
Two hundred and thirty-nine passengers perished in that crash, but investigators are yet to locate the black box.
Aviation giant Airbus is at the forefront of efforts to upgrade black boxes by giving them the ability to self-eject.
Airbus Executive Vice President for Engineering Charles Champion told AFP, "If we have a deployable recorder it will be much easier to find."
Ejectable or "deployable" recorders would separate from the tail during a crash and float, emitting a distress signal.
The United Nations' aviation agency, the International Civil Aviation Organisation, has called for key data to be recoverable in a "timely manner" from airplanes delivered after 2021.
Deployable recorders have long been used in the military but some in the industry, including Boeing, have expressed doubts about their safety, citing the risk of an "accidental deployment."
A series of accidents over water including the EgyptAir disaster and wider safety issues are likely to be discussed at a meeting of global airline companies in Dublin this week.