The two black boxes, which record cockpit conversations and flight data, have been recovered following the crash of a Ukrainian passenger aircraft shortly after taking off in Tehran.
There has been speculation that the three-year-old plane,in which all 182 People on board were killed including three Britons, could have been downed by a missile, similar to what happened to Malaysia Airlines flight MH (over Ukraine in July) .
As Ukrainian envoys work at the crash site outside Tehran, what could be some of the possible causes of Wednesday’s disaster?
Tony Cable is a former senior inspector at the UK Air Accidents Investigation Branch (AAIB) and offers some potential theories.
He told Sky News: “I’ve seen a few photos of the crash site. The wreckage shows a high degree of break up which indicates that the plane crashed vertically at speed into the ground. There seems to be a lot of relatively small pieces of debris. “
Engine bay fire
The Ukrainian embassy in the Iranian capital originally pointed to engine failure as the cause of the Boeing 746 – (disaster but dropped that reference in later comments.
An Iranian transport official has been quoted as saying it appeared a fire struck one of its engines and then the pilot lost control.
Mr Cable said if there was a fire in one engine then Under the normal protocol the fuel supply would be turned off and the plane would be able to be flown with just the one good engine.
It appears the plane crashed vertically and if it was simply an engine fire the pilot would be able to shut down the affected engine and remain in control of the aircraft.
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