Pilots of the EgyptAir plane which crashed into the Mediterranean Sea killing all 66 people on board in 2016 were reportedly smoking in the cabin, sparking a fire in the cockpit, according to a new report sent by French aviation experts to the Paris court of appeal.
The flight left Paris' Charles de Gaulle Airport and was bound for Cairo but disappeared from radars on 19 May 2016 and crashed south of the Greek island of Crete where the black box was eventually found.
Egypt, Greece, France, England, Cyprus, Italy and a US navy patrol aircraft worked together to search for the plane after it disappeared from the radar.
The Egyptian authorities themselves have never released a report on the fatal crash but at the time said that explosives had been found on the remains of the victims and that terrorism was the likely cause of the crash.
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This was later refuted by France's civil aviation bureau, who said that it was most likely a fire had broken out in the cockpit which spread and resulted in loss of control of the aeroplane. At the time they did not know the exact cause of the fire.
This latest document sent to the Paris court of appeal last month has now revealed that a cigarette one of the pilots was smoking ignited oxygen leaking from the co-pilot's mask, reports Italian newspaper Il Corriere della Sera.
Smoking in the cabin was not banned at the time of the crash, according to the report.
The report was compiled after further examination of black box data on which investigators could hear oxygen hissing from the mask, the valve of which was set to the emergency position which allows oxygen to be released at a higher pressure.
French judges are investigating the case as 15 of the people on board were French. Among the dead were 30 Egyptians, 15 French, two Iraqis and one Brit.