Yak Service YK42 at Yaroslavl on Sep 7th 2011, failed to climb on takeoff
Last Update: November 2, 2012 / 21:44:05 GMT/Zulu time
erroneous actions by the crew, especially by applying brake pedal pressure just before rotation as result of a wrong foot position on the pedal during the takeoff run. This led to braking forces on the main gear requiring additional time for acceleration, a nose down moment preventing the crew to establish a proper rotation and preventing the aircraft to reach a proper pitch angle for becoming airborne, overrun of the runway at high speed with the elevator fully deflected for nose up rotation (producing more than double the elevator forces required to achieve normal takeoff rotation). The aircraft finally achieved a high rate of nose up rotation, became airborne 450 meters past the runway end and rotated up to a supercritical angle of attack still at a large rate of pitch up causing the aircraft to stall at low altitude, to impact obstacles and ground, break up and catch fire killing all but one occupants.
Had the crew rejected takeoff even above V1, with about 1000 meters of runway remaining available after the failed first attempt to rotate the aircraft, an accident would have been averted.
Forensic examination revealed the presence of a psychoactive drug (phenobarbital) in the first officer's body causing an inhibiting effect on the central nervous system. Performing duties as a crew member under the influence of this drug is prohibited by Russian Law.
Contributing factors were:
- serious shortcomings in the re-training of the crew members with regards to the Yak-42, which did not take place in full, was spread out over a long period of time and took place while the crew remained in full operation on another aircraft type (Yak-40), which led to a negative transfer of skills, especially a wrong position of the foot on the brake pedal on the Yak-42.
- Lack of supervision of the re-training
- errors and missed procedures by the crew in preparation and execution of the takeoff
- inconsistent, uncoordinated actions by the crew in the final stages of the takeoff
The MAK released the following findings as to the reason:
- The aircraft and all its systems were working properly upon departure from Yaroslavl. No failures of any system including brakes could be identified. There was no fire, explosion or destruction of the aircraft before impact with obstacles.
- The length and condition of the runway as well as weather conditions permitted a safe takeoff.
- The operational as well as business model of Yak Service, with respect to its operational and financial scheme, did not allow to provide safe operation.
- Organisation of flight activities as well as supervision of flight safety was absent in the company
- In 2011 there were significant shortcomings within the airline although it passed the compliance testing certification carried out by two organisations (named in the report)
- The re-training of the captain as well as the first officer was conducted in violation of current regulations, stretched over time to be combined with the development of flight operations on other types than the Yak-40
- Supervision over re-training procedures and further flight operations was insufficient
- Crew rostering had been done without consideration of important professional aspects, for example the crew consisted of two leaders with the authority of the first officer being higher than the captain's
- The first officer was unfit to fly due to influence of medicine (Phenobarbital). The drug had an inhibiting effect on the central nervous system
- The first officer did not conduct a number of important procedures and computation in preparation for takeoff
- The captain, conducting a balanced takeoff, took the incompetent decision to begin the takeoff roll not from the beginning of the runway
- No crew activity could be heard/observed during the takeoff run
- During the takeoff run, just prior to begin rotation, an incorrect leg position produced brake pedal pressure causing a retarding moment on the main landing wheels and a nose down moment counteracting rotation preventing rotation at Vr.
- During the takeoff run the crew fell back into the habit of operating a Yak-40 rather than a Yak-42 (most important difference: the position and feel of brake pedals)
- Simulation of the flight and the flight experiment showed a further compression of brake pedals could produce a retarding force of about 8000kg (78,500N, 17,600 lbs).
- After the failed rotation the crew did not take a decision to reject takeoff, but continued the takeoff accelerating the engines to maximum takeoff thrust
- The aircraft overran the runway end at a speed of 230kph (125 knots).
- The actions of the crew in the final stages of the takeoff were uncoordinated and inconsistent.
An AVI video showing the reconstructed flight was later released.
This article is published under license from Avherald.com. © of text by Avherald.com.
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