Preliminary flight-recorder data from the crashed Yakovlev Yak-42 at Yaroslavl indicates the aircraft's flaps were deployed to their 20° take-off setting and its engines were functioning before it collided with obstacles.
Russia's Interstate Aviation Committee (MAK) has also determined that the horizontal stabiliser was positioned to the 8.7° pitch-up setting.
Investigators are attempting to explain why the trijet, which had 45 occupants, failed to climb away from Yaroslavl airport during a service to Minsk on 7 September, breaking up as it struck terrain just a few hundred metres from the end of runway 23.
The aircraft appears to have gained little height during the departure, striking a navigation aid - possibly the localiser at the far end of the runway - before impact.
MAK said that, although the aircraft's fuselage came to rest in a river, both the cockpit-voice and flight-data recorders are in satisfactory condition.
Forty-three of those on board the Yak-42, operated by Yak Service, were killed in the accident.