Investigators have found no evidence that the pilots of the ill-fated Sukhoi Superjet 100 which crashed in Indonesia attempted any evasive manoeuvre before the jet collided with terrain.
Simulation analysis in the wake of the 9 May accident on Mount Salak, south of Jakarta, shows that the collision was inevitable during the final 14s of flight.
Recorded flight data shows that the aircraft had been maintaining an altitude of 6,000ft but was unintentionally left to drift towards the mountain after the crew, distracted by other matters, failed to keep the jet turning in a clockwise holding orbit.
The last 2min of radio altimeter information shows steadily-rising terrain below the aircraft after it exited the orbit - travelling south for 4nm (7.4km) on the last heading selected by the crew - while the pilots discussed a return route to Jakarta.
This closure rate steepened after the pilots belatedly set a new heading, intending to turn the aircraft northwest but effectively steering it towards the peak.
Although the nearest weather station was 7nm away, conversation between the pilots suggests the presence of heavy cloud which largely obscured the view of the ground.
"It is reasonable to conclude that the cloud cover prevented the pilot's being able to see the mountainous terrain," says the Indonesian National Transportation Safety Committee. It notes that the crew was preparing to request descent to 1,600ft, further illustrating that they were unaware of the looming high ground.
The terrain-awareness warning system sounded several alerts - including a "pull up" instruction - but the crew switched it off, 10s after it started sounding, believing it to be spurious.
Flight-control data shows no evidence of evasive manoeuvring over the first 24s following the warning, the time interval during which escape would have been possible. For the 14s beyond this interval, says the inquiry, any pilot action "would not successfully avoid collision with terrain".
Seven seconds before impact the captain briefly flicked the sidestick back - a momentary input which disconnected the autopilot - but the inquiry determined that this "could not be an indication of an attempted escape action".