Flight MS804: What Do We Know So Far?

French investigators have confirmed that smoke was detected on flight MS804 before it crashed. So what does that tell us about the cause of the crash?

Aviation experts Philip Baum, the editor-in-chief of Aviation Security International, and Dr Stephen Wright, lecturer at the University of Leeds, analyse the available evidence for Sky News.

RULED OUT 

:: The smoke warning data, in particular the fact that the emergency lasted for several minutes, appears to rule out the possibility that a bomb blew the plane apart.

:: The smoke warnings also suggest that the crash was not an "aircraft-assisted suicide", as was the case with Germanwings Flight 9525, where co-pilot Andreas Lubitz deliberately crashed the jet in the French Alps in March 2015.

POSSIBILITIES

:: Although the plane was not immediately blown apart by a bomb, it is still possible that an explosive device detonated on board - and caused a fire, which spread through the aircraft.

If this were the case, the pilots were trained to "aviate and navigate" the aircraft to safety, before making any attempt to communicate to the ground or to passengers. This might account for the apparent lack of any Mayday distress call from the pilots. 

:: It is possible that the fire was caused by someone smoking in the toilet closest to the cockpit. This would fit with evidence suggesting that smoke was initially detected in the area at the front of the plane, near to the lavatory.

:: It is also possible that a fire started in the avionics bay at the front of the plane.

This bay is a space inside the structure of the aircraft, under the cockpit, where electronic devices such as communications radios and navigation systems are normally found.

Although this is possible, it seems more unlikely given the speed at which the smoke appears to have spread through the plane.

KEY QUESTIONS

:: Why were there no communications whatsoever in the several minutes after smoke was initially detected, before the plane plummeted into the sea?

There were two pilots, so it is perhaps unusual that no call was made. Given this evidence, is it possible that the pilots were somehow incapacitated and unable to communicate?

:: What will forensic analysis of the debris and wreckage reveal? Will there be evidence of explosive residue on the items?

:: What will recordings from the black boxes reveal? These recordings will detail any communications between the two pilots in the minutes before the crash.

:: Why were there no communications whatsoever in the several minutes after smoke was initially detected, before the plane plummeted into the sea?

There were two pilots, so it is perhaps unusual that no call was made. Given this evidence, is it possible that the pilots were somehow incapacitated and unable to communicate?

:: What will forensic analysis of the debris and wreckage reveal? Will there be evidence of explosive residue on the items?

:: What will recordings from the black boxes reveal? These recordings will detail any communications between the two pilots in the minutes before the crash.