Russian investigators have determined that a pilot of the Yakovlev Yak-42 which crashed on departure from Yaroslavl had inadvertently been braking during the take-off roll.
The inquiry found that the crew had accumulated extensive flight time on the smaller Yak-40 in which, said the Interstate Aviation Committee (MAK), techniques include using feet to cover the brake in case of rejected take-off.
But the pedal design on the Yak-42 is different. MAK said there had been "negative transference" of pilot skills, regarding foot position, by the crew.
The aircraft, bound for Minsk on 7 September, failed to rotate and overran, hitting an antenna before crashing in a river.
MAK has criticised "serious shortcomings" in the training of the crew, as well as the management of safety at the carrier, Yak Service. MAK said the organisation of the airline "did not allow" it to perform safe flight operations. The airline nevertheless passed regulatory compliance tests earlier this year.
Only one of the 45 occupants - including an entire high-profile ice-hockey squad - survived the accident, and investigations concentrated on a braking force which had emerged during the take-off roll.
The inquiry found that in the history of Yak-42 operations, amounting to 1.2 million flights, there had been only five cases of brake failure, and that none of these was similar to the Yaroslavl accident.
MAK said the parking brake was off, and added that the chances that a technical failure could lock the main wheels spontaneously was "virtually impossible" given their design.
The aircraft had been carrying sufficient fuel for the flight, its weight and balance were within limits, and there was no evidence of failure in the engines or aircraft systems - including jamming of the elevator.
Control and stability was in line with the type's characteristics, said MAK, and the crew checked that the rudder and ailerons were responding correctly to control inputs.
MAK found that the crew had not performed a correct take-off calculation, citing the V1 speed as 102kt rather than 113kt. The inquiry also said that the crew did not decide to abort the take-off despite the failure to rotate.