Investigators have retrieved two of the three flight recorders from the Dagestan Airlines Tupolev Tu-154M which crashed at Moscow Domodedovo yesterday.
The Interstate Aviation Committee (MAK) states that it has started a preliminary analysis of the flight-data recorder and begun reading data from a second parametric device.
It has yet to obtain the cockpit-voice recorder.
"We have requested technical flight operations and maintenance documentation for the aircraft," adds MAK.
Both flight recorders retrieved so far are in satisfactory condition, the authority says.
Two people among the 169 passengers and crew were killed as the tri-jet left the runway and broke up while attempting an emergency landing.
Preliminary information from MAK indicates it suffered a serial power loss from its engines after leaving Moscow Vnukovo for Dagestan.