Smoke was detected on EgyptAir Flight 804 shortly before it plunged into the Mediterranean on May 19, 2016, killing all 66 aboard, and initial analyses pointed toward terrorism. Now, a report from French investigators points to something far less nefarious: a fire caused by a cigarette smoked by one of the pilots, per CBS News. According to a nearly 140-page document seen by the Italian newspaper Corriere Della Sera, the fire that eventually doomed the plane headed from Paris to Cairo was probably the result of combustion caused by a leak in the co-pilot's oxygen mask and "a spark or a flame" from the cigarette in question being smoked by either the pilot or co-pilot.
The report notes that a maintenance engineer had left the co-pilot's oxygen mask in "emergency" mode rather than in "normal" mode after a mask replacement three days before the crash, per Al Jazeera. It's not clear why such a replacement was made, but in 2018, experts who spoke before a Paris court noted that "the replacement of this equipment requires very careful verification ... oxygen leaks being particularly dangerous," reports CBS. The French investigators' report also details a hissing or "rustling" sound picked up by a microphone on the mask in the minutes before the accident.
The Independent notes that smoking in the cockpit was still permitted by the airline at the time of the crash, and that pilots regularly did so. France's air accident investigation agency said in 2018 that it believed a fire in the cockpit led to the crash; findings from Egyptian officials' own investigation were never made public. Victims' families can't believe it's taken this long to get closer to the truth, saying the process has been exhausting. "We want to know why we lost our loved ones, and we [didn't] know that till this day," a woman who lost both her brother and father in the crash tells Corriere Della Sera. (Read more EgyptAir stories.)