A plane that crashed into a snowy field in Siberia, killing 31 people, appears to have been improperly de-iced, but there was no indication that negligence caused the crash, Russia's civil aviation chief said. Investigators said evidence so far suggests a technical failure as the cause.
The twin-engine turboprop belonging to UTair crashed shortly after takeoff Monday from the snowy western Siberian city of Tyumen with 43 people aboard. Twelve people have been hospitalized in serious condition.
The state news agency RIA-Novosti quoted Rosaviatsiya head Alexander Neradko as saying there was evidence "that the treatment of the plane with de-icing agents was not done at the necessary level." However, he also said there was no basis yet "to connect this with the causes of the crash."
The ATR-72-200 took off at 7:40 a.m. from Tyumen, a regional centre in Siberia about 1,700 kilometres (1,000 miles) east of Moscow, heading for the oil town of Surgut, about 650 kilometres (400 miles) away.
The plane came down in a field about three kilometres (two miles) away from the Tyumen airport, breaking into three sections upon impact. Part of it was destroyed by a fire that burned at least six people to death, said Sergei Kiselyov, police chief at the Roshchino airport in Tyumen.
Investigators said evidence so far points to a technical failure of the French/Italian-made aircraft. They noted that witnesses reported seeing smoke coming from its engines as the plane came down and said its pilots had tried to return to the airport.
The federal Investigative committee said while equipment failure appeared to be the most likely cause of the crash, pilot error or mistakes by traffic controllers had not been ruled out.
The plane's flight recorders have been recovered and sent to Moscow for examination. UTair said the two other ATR-72-200s in its fleet would be temporarily taken out of service for inspection.
ATR said the plane was built in 1992 and had been part of UTair's fleet since 2008. All of the 39 passengers and four crew on board were Russian, according to a list by Utair.
"One survivor stood up on his own and waited until he was given medical help and only then felt worse," Kiselyov told RIA Novosti.
Russia has seen a string of deadly crashes in recent years. Some have been blamed on the use of aging aircraft, but industry experts point to a number of other problems, including poor crew training, crumbling airports, lax government controls and widespread neglect of safety in the pursuit of profits.
Pilot error was blamed for a September crash in Yaroslavl, a Russian city 250 kilometres (150 miles) northeast of Moscow, that killed 44 people, including a professional hockey team.
Pilot error and fog also were ruled the main causes of a crash in April 2010 that killed Poland's president and 95 other people as their plane was trying to land near Smolensk, in western Russia.
ATR-72s have been involved in several accidents in past years.
Most recently, one went down in bad weather in Cuba in November 2010, killing all 68 people on board. Cuban aviation officials said the investigation showed there was nothing wrong with the aircraft.