Russian investigators have disclosed that the crashed Gazpromavia Yakovlev Superjet 100 crew switched to manual control after the aircraft started to pitch down, briefly arresting the descent, before it entered a steep fatal dive.
The aircraft took off from Lukhovitsy airport, bound for Moscow Vnukovo, on 12 July following “periodic maintenance” by a United Aircraft facility, says the Interstate Aviation Committee.
It climbed with its autothrottle active, and the autopilot was engaged at 550ft.
Five minutes into the flight, the inquiry says, the aircraft was “virtually level” at an altitude of 5,160ft – with an attitude 5-6° nose-up and an angle-of-attack of 10-11° – when it transitioned to 4° nose-down and began to descend.
At the point of this transition the airspeed was 200kt and rising while the slats and flaps were retracting synchronously to their fully-stowed position.
The autopilot and autothrottle were disengaged as the Superjet descended, and the crew operated the aircraft manually, briefly halting the descent at 4,500ft and climbing back to 4,750ft.
But investigators state that the aircraft’s airspeed then increased to 320kt, with an overspeed alarm activating, and the aircraft entered a steepening dive.
“The descent could not be stopped by the crew’s fully deflecting the [sidestick rearwards],” says the inquiry, adding that the PowerJet SaM146 engines continue to operate throughout.
With the crew unable to recover from the dive, which reached 17,000ft/min, the aircraft crashed into a forest near Apraksino at an airspeed of 365kt, pitched nose-down at 25° and banked 25° to the right.
None of the three crew members – two pilots and a flight attendant – survived the accident. The inquiry has not specified the reasons for the in-flight upset, but says it has sent recommendations for corrective safety measures to Russian authorities.
