Azur B752 at Goa on Feb 6th 2017, pitch up to 30 degrees on autopilot triggers stick shaker on departure

Last Update: July 25, 2018 / 17:14:16 GMT/Zulu time

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Photo of Azur Air VP-BLV, Boeing 757-200 — Azur Air VP-BLV, Boeing 757-200 (Photo credit: Papas.Dos / Flickr / License: CC by)

Incident Facts

Date of incident
Feb 6, 2017

Classification
Report

Airline
Azur Air

Flight number
ZF-6128

Departure
Goa, India

Destination
Rostov on Don, Russia

Aircraft Registration
VP-BLV

Aircraft Type
Boeing 757-200

ICAO Type Designator
B752

An Azur Air Boeing 757-200, registration VP-BLV performing flight ZF-6128 from Goa (India) to Rostov on Don (Russia) with 232 passengers and 7 crew, was climbing through 2770 feet MSL out of Goa's runway 26, autopilot and autothrust were engaged, the captain was pilot flying, when the aircraft pitched up reaching 29.4 degrees nose up, the speed decayed and the stick shaker activated. Upon stick shaker activation the captain disengaged the autopilot, lowered the nose to 2.2 degrees nose down, after the stick shaker ceased increased engine thrust to near takeoff thrust. The aircraft subsequently continued to Rostov for a safe landing without further incident.

Rosaviatsia released their final report in Russian concluding the probable causes of the incident were:

The incident occurred due to the loss of speed prior to the activation of the stall warning with autopilot and autothrust engaged.

Factors contributing to the incident were:

- the activation of the mode V/S (instead of FLCH) which increased the vertical speed more than necessary and led to the increase in angle of attack and loss of speed

- after activation of the autoflight systems the flight crew was not sure whether the flight parameters (flight speed and pitch/vertical speed) corresponded to the FLCH mode

- insufficient crew resource management, evident by the lack of speed control and monitoring (mutual cross check of captain and first officer)

- the various different displays of airspeed on the various Boeing 757 aircraft of the operator may have contributed to the worsening situational awareness

- the display of a trend vector could possibly contribute to an earlier detection of deviations, e.g. dangerous loss of airspeed, by the flight crew

Rosaviatsia reported the aircraft departed in visual meteorological conditions for a non-scheduled passenger flight from Goa to Rostov. The flaps were set to 5 degrees, flex takeoff settings were used for departure. Climbing through 2777 feet the IAS reduced to 134 KIAS, less than acceptable for flaps 5, as result of the pitch angle having increased to 29.4 degrees nose up, the stall warning (including stick shaker) activated. The captain disengaged the autopilot and pitched the aircraft down to 2.2 degrees nose down, a sink rate of 3800 fpm resulted, the IAS increased and the stick shaker ceased. The captain then increased engine thrust to near takeoff thrust.

The investigation commission established that climbing through 888 feet AGL, almost simultaneous with the change of the thrust mode T/O to CLB mode, the pitch channel changed to V/S mode, which is not according to Flight Manual and standard operating procedures, most likely this mode was inadvertently selected by the first officer. About 1.5 seconds later the pitch channel returned to FLCH mode for about 3 seconds, then the "C" channel of the autopilot was activated, simultaneously the pitch channel changed to V/S again with a commanded climb rate of 3700 fpm (the current climb rate at the time of the mode change). The reason for this last transition to V/S has not been established. The maximum climb rate that could have been sustained in this configuration without loss of airspeed was 1600 fpm. At the time of the last transition to V/S the airspeed was 195 KIAS after having reached a maximum of 201 KIAS.

Rosaviatsia reported that due to noises from the cabin (intra-cabin talks) did not permit to assess the communication between the flight crew, however, the developing situation permits to conclude that the flight crew did not call out the flight mode changes, did not monitor the flight mode announciators and did not verify the autopilot.