Data transmitted from a doomed EgyptAir flight minutes before it fell off radar screens suggests a fire had broken out on board the plane, according to an aviation industry website.
AvHerald.com is reporting that data transmissions from EgyptAir Flight 804 to ground stations show smoke was detected in a bathroom near the cockpit. NBC News has confirmed the messages are authentic.
The ACARS (Aircraft Communications Addressing and Reporting) system messages suggest the possibility of smoke or a fire in close proximity to the electronics and equipment bay of the Airbus below the floor of the cockpit.
Messages also seem to indicate there may have been a problem with the controls and computers, critical to controlling the plane.
"We don't know what it is, but it's a clear indication that something was terribly wrong on flight 804," John Cox, a former Airbus A320 pilot, told NBC News. The EgyptAir plane that crashed was an Airbus A320.
The website reported that investigators are poring over the ACARS messages to determine what may have happened on the plane before it went down.
Sixty-six people were aboard the Airbus A320 flying from Paris to Cairo before it vanished early Thursday morning. Wreckage from the plane was found Friday in the Mediterranean Sea some 180 miles off the Egyptian coast.
Terrorism has been cited as a potential cause of the crash — though officials have cautioned against speculation and there has been no credible claim of responsibility from any group.
U.S. intelligence sources tell NBC News they are aware of the AvHerald.com report about the ACARS data and have no reason to believe the information is not accurate.
The report includes the plane-to-ground messages sent in the final minutes of the flight:
00:26Z 2600 SMOKE LAVATORY SMOKE
00:27Z 2600 AVIONICS SMOKE
00:28Z 561100 R FIXED WINDOW SENSOR
00:29Z 2200 AUTO FLT FCU 2 FAULT
00:29Z 2700 F/CTL SEC 3 FAULT
An "FCU" refers to a unit in cockpit the pilot uses to input instructions into the flight computer. "SEC3" refers to the computer that controls the spoilers and elevator computers of the plane.
No mayday call was sent from the jet before it disappeared off radar.
Former National Transportation Safety Board investigator Greg Feith said the fact that the smoke warning occurred so soon before the plane disappeared suggest something more catastrophic than a discarded cigarette or electrical fire.
"Electrical fires don't burn that fast, and of course if somebody were to put a cigarette in a trash can with paper towels it definitely wouldn't have burned that fast," Feith said.
"It would have set off the sensor but the flight crew is trained to handle those types of fires and it would have given them time. Plus, they probably would have made a radio call," he said.
Meanwhile, investigators are looking at anyone with access to the EgyptAir plane while it was sitting on the ground, including baggage handlers, caterers, cleaners and fuel truck workers.
The EgyptAir plane was on the ground at four different airports in the 24 hours before the crash — in the Eritrean capital Asmara, Cairo, Tunis and Paris.