Scheduled Revenue Flight

Controlled flight into terrain.

It was determined that the runway surface was contaminated with snow and has not been cleared prior to takeoff. It was also reported that the runway lights and edge markings were not clearly visible due to snow.

The accident was the consequence of the following factors:
(1) An aerodynamic stall that occurred when the flightcrew allowed the airspeed to decay to stall speed following a very poorly planned and executed approach characterized by an absence
of procedural discipline;
(2) Improper pilot response to the stall warning, including failure to advance the power levers to maximum, and inappropriately raising the flaps;
(3) Flightcrew inexperience in 'glass cockpit' automatic aircraft, aircraft type, and in seat position, a situation exacerbated by a side letter of agreement between the company and its pilots;
(4) The company's failure to provide adequate crew resource management training, and the FAA's failure to require such training;
(5) The company's failure to provide adequate stabilized approach criteria, and the FAA's failure to require such criteria; and
(6) The unavailability of suitable training simulators that precluded fully effective flightcrew training.
Note: Items 1, 2, and 3 were approved by a Board vote of 4-0. Item 5 was adopted 3-1, with the dissenting Member believing the item was a contributory cause. The Board was divided 2-2 on items 4 and 6, two Members believing them causal and two Members, contributory.

The commission found that the air starter malfunction occurred when the engine was started due to a structural element of the air conditioning system, probably a fragment of the air-to-air radiator (VVR) splitter of engine n°2, hit under the constant pressure flap. This became possible due to the lack of protection against the ingress of foreign objects from the air lines and the low operational reliability of the VVR. A constant supply of air under pressure from the engines operating at a mode close to the nominal through an open damper led to the starter not switching off and the turbine rotor spinning up to off-design speed with the alarm "Dangerous starter speed" being triggered, which was detected by the flight engineer after starting all the engines. Pressing the starter shutdown button did not turn off the alarm. There were no other signs of failure other than the operation of the warning lamp. The crew, believing that the alarm was false, made the wrong decision to take off, which was a consequence of the unwillingness to act in such a situation due to shortcomings in the regulatory documentation, information support, as well as insufficient information content of the starter's technical condition monitoring system in the cockpit. Laying the mains of all three hydraulic systems through the fire-hazardous compartment of the engine n°2 is a constructive disadvantage of the Tu-154M aircraft.

Engine failure for unknown reasons.

The pilot-in-command's failure to maintain adequate separation behind the Boeing 757 and/or remain above its flight path during the approach, which resulted in an encounter with wake vortices from the 757. Factors related to the accident were: an inadequacy in the ATC procedure related to visual approaches and VFR operations behind heavier airplanes, and the resultant lack of information to the Westwind pilots for them to determine the relative flight path of their airplane with respect to the boeing 757's flight path.