Still, the Moscow-based Interstate Aviation Committee, which is conducting the crash probe, had no conclusions yet about the cause of the crash that killed 43 people, mostly members of a top Russian ice hockey team.
The comments came as aviation experts examined flight data recorders from the crashed plane and began safety checks Friday on Yak-42 jets nationwide.
The chartered Yak-42 jet crashed Wednesday into the sides of the Volga River on a sunny, clear day moments after taking off near Yaroslavl, a city 150 miles (240 kilometers) northeast of Moscow.
It was one of the worst aviation disasters ever in sports, shocking Russia and the world of hockey, for among the dead were 36 players, coaches and staff of the Lokomotiv Yaroslavl hockey team. The team had been heading to Minsk, Belarus, to play its opening game of the Kontinental Hockey League season.
Two men survived the crash — player Alexander Galimov and crew member Alexander Sizov — but they were in critical condition Friday, both in medicated comas after being transferred to Moscow for treatment. Hospital officials said Galimov had burns over 90 percent of his body.
The Interstate Aviation Committee said magnetic tapes holding the flight information in the data recorders were wet, but its experts have begun deciphering those segments that have dried out, learning about the engines. The committee didn't specify, however, whether the engines were giving the full thrust.
The Tunoshna airport's runway is three times longer than required for that type of plane but the plane still failed to accelerate sufficiently before takeoff, Russian Deputy Transport Minister Valery Okulov said.
Authorities were also checking fuel supplies at the Tunoshna airport, suspecting that low quality fuel could have caused the crash. The airport has been allowed to resume operations but planes were barred from using local fuel.
Yaroslavl Gov. Sergei Vakhrukov, however, insisted that the fuel couldn't have been the cause, since another plane using the same fuel had flown without any problems.
The crashed jet was built in 1993 and one of its three engines was replaced a month ago, transportation officials said.
Aviation authorities also launched safety checks on all the approximately 60 Yak-42 jets currently in service in Russia, which was expected to lead to disruptions in service. An Associated Press reporter was among the passengers ordered to disembark Friday from a Yak-42 jet bound on an internal flight from Moscow.
Of the six Yak-42s checked so far, three have been grounded, Rostransnadzor transport safety watchdog said. It said their owners will have to fix unspecified flaws before resuming their flights.
In Yaroslavl, where there has been an outpouring of public grief over the deaths of the hockey players, a memorial service was to be held Saturday at the team's arena. Several squads from the Kontinental Hockey League were traveling to Yaroslavl to take part.
Thousands of fans have already come to the Yaroslavl arena to pay their respects, laying mounds of red roses and carnations outside its walls.
President Dmitry Medvedev has called for sweeping reforms to Russia's aviation industry, including replacing aging Russian jets with Western planes.
Experts blame Russia's poor aviation safety record on an aging fleet, weak government controls, poor pilot training and a cost-cutting mentality.