Investigators are performing preliminary checks as the inquiry into the Tatarstan Airlines Boeing 737-500 crash at Kazan begins to gather data on the fatal flight.
Fuel samples are to be drawn to test its quality, says the Russian federal Investigative Committee which is conducting a parallel legal inquiry into the crash.
It states that the wreckage site is “vast”, covering some 250,000m2, following the 17 November accident.
Airport surveillance video images show that the aircraft fell “perpendicular” to the ground, it adds, generating a large explosion. The video images are being “studied in detail”, says the Investigative Committee.
Images purporting to show the last moments of the flight appear to indicate that it was in a near-vertical nose-down attitude at the point of impact.
Documentation relating to the flight is also being gathered. The Investigative Committee says it is exploring whether technical malfunction, weather conditions and the possibility of operational error contributed to the accident.
It will also evaluate the “adequacy and effectiveness” of safety oversight at the carrier.
“Only after the full range of investigative and legal actions will it be possible to draw conclusions about the cause of the crash, as well as the responsibility of specific individuals,” it says.
Russian federal transport authority Rosaviatsia says the aircraft came down between the runway and the main taxiway after operating a service from Moscow Domodedovo. There were no survivors among the 44 passengers and six crew.
Investigators from the Interstate Aviation Committee, which is performing the technical probe, have received the two flight recorders. UK investigators are being dispatched to aid the inquiry, the Air Accidents Investigation Branch confirms.