But preliminary information from Russia’s Interstate Aviation Committee states that there was no “significant” pitch deviation from the control column as the aircraft dove towards the ground.
The jet, arriving from Moscow on 17 November, sharply climbed to 700m (2,300ft) during the go-around despite missed approach procedures showing a level-off altitude of 500m.
Both pilots were experienced on the 737: the captain had just over 2,500h on type, while the first officer was nearing 2,000h. But neither had logged more than around 150-200h total experience beyond this. The captain was licensed for Cat I approaches and the first officer for Cat II.
Investigators state that the aircraft – performing an instrument approach to runway 29 – had been some 4km laterally off course and, after the final turn in the procedure, was “significantly” to the right of the approach path.
The crew attempted to correct by selecting a heading of 250° but the localiser was not captured until the aircraft was just 2km from the runway threshold.
While the aircraft made a corrective turn in order to align with the runway, its height of some 1,000ft was too far above the glideslope. As the 737 passed the middle marker beacon the crew told air traffic control that the aircraft was not positioned for landing and began the go-around.
The engines were powered up to 83% of N1 and, aided by flap and gear retraction, the aircraft climbed at 25°. Airspeed bled away and the 737’s speed trim system – which acts to stabilise the airspeed in such situations – began adjusting to favour a lower nose attitude.
As the aircraft continued to climb it passed through the normal 500m height for missed approaches at Kazan. Its airspeed fell from 150kt to 125kt before the crew acted to reduce the pitch with the control column, but the speed continued to fall to a minimum of 117kt.
Investigators state that the aircraft did not exceed angle-of-attack operating limits. As a result of the crew’s actions, its climb peaked at 700m. The 737 then pitched into a steep dive, triggering “sink rate” and “pull up” warnings before it hit the ground nearly vertical, at over 240kt, and disintegrated.
The engine thrust had remained essentially at the go-around setting to the point of impact.
None of the 44 passengers and six crew members survived. The approach had been conducted at night with a low cloud base, in light rain and snow with gusting winds.
Investigators are yet to release details of communications within the cockpit, as they work to identify the voices and speech, but are satisfied that only the pilots were present.
While the cause of the accident is yet to be formally determined, the Interstate Aviation Committee is recommending improved training for pilots during missed approaches, particularly regarding attention to procedures and recognition of possible aircraft upset.
It is also advising that air traffic control processes be examined to explore whether controllers could provide greater assistance to crews in cases where aircraft are deviating significantly from the required course.
(David Kaminski-Morrow - Flightglobal News)