Die MAK Interstate Aviation Committee (russische Luftfahrtbehörde) hat ihren Zwischenbericht zum Absturz von Flug FZ981 vorgelegt (PDF). Resümee: Maschine OK, Piloten … über Tote soll man nix Schlechtes sagen. Das Wesentliche finden Sie auf Seiten 5 und 6:
- Both approaches (from the height of about 600 m) were performed with autopilot and autothrottle disengaged in flight director mode without significant heading or altitude deviations from the glideslope.
As the crew were proceeding with the approach (as per the FDR and CVR readout), the crew decided to go around again at a height of 220 meters (4,5 km before the runway) and initiated climb with vertical speed of up to 20 mps setting the engines to maximum takeoff/go-around thrust of 101 – 102% (N1).
One of the probable causes of the go-around decision could have been the 20-knot increase of indicated speed to as much as 176 knots within 3 seconds, which might have been an indication of a windshear.
In the course of the go-around the crew set flaps to 15° and retracted the landing gear.
At the height of 1900 ft (approx. 600 m) after reaching the pitch angle of 18° the pilot flying pushed on the control column, which led to a decrease in vertical acceleration of up to 0.5, increase in forward speed and, consequentially, automatic retraction of flaps from 15° to 10° at a speed of over 200 knots.
The short-term decrease in engine thrust within 3 seconds resulted in decreasing speed and flaps extension to 15°, although the following crew inputs to regain maximum takeoff/go-around thrust led to speed increase and reiterated automatic flaps retraction to 10°. The flaps remained in the latter configuration until the impact.
The pilot flying, by pulling up the control column, continued climbing with a vertical speed of as much as 16 mps.
At a height of 900 m there was a simultaneous control column nose down input and stabilizer nose down deflection from -2,5 deg (6,5 units) to +2,5 deg (1,5 units) (the FDR recorded a nose down stabilizer input from the stabilizer trim switch of the control wheel lasting 12 seconds, while the CVR record contains a specific noise of rotation of the trim wheels located on both sides of the central pedestal), as a result the aircraft, having climbed to about 1000 m, turned into descent with negative vertical acceleration of -1g.
The following crew recovery actions did not allow to avoid an impact with the ground.
At 00:41:49 the aircraft hit the runway about 120 m from the threshold with a speed of over 600 kmph and over 50 degrees nose down pitch.