Faulty brakes may have been to blame for a Russian airliner sliding off the runway and smashing onto a highway near Moscow.
Investigators said they were examining the black boxes to try to determine the cause of Saturday's crash, which cracked the wings off the Tupolev-204 plane and split the fuselage clean into three pieces.
Five people were killed in the crash including a crew member who died from her injuries in hospital today.
If investigators find bad brakes were at fault, it would match a warning issued to the state-owned Tupolev by Russia's aviation authority to fix problems with the brakes that may have caused a Tu-204 with 70 people onboard to go off a Siberian runway on 21 December.
Any sign that the catastrophe during peak holiday travel could have been avoided will worsen concerns over the country's poor air-safety record, despite President Vladimir Putin's calls to improve controls.
"After landing the pilot uses all the available brake systems on the plane, but for some reason the machine did not stop," a member of the investigation team said.
"Most likely it was faulty reverse engines or brakes."
Despite icy weather conditions, the plane had been piloted by an experienced crew with many hours of flying under their belt, according to Russia's aviation safety body.
Television footage showed the jet with smoke billowing from the tail end and the cockpit broken clean off after the crash.
A photo showed a crew member, still strapped to a seat, sprawled on the pavement after apparently being hurled far from the plane during its impact with the highway barrier.
Red Wings, whose fleet includes nine of the Soviet-designed Tu-204 jets, said it would not retire them from use.