Investigators on Friday raided several departments of the Federal Air Transportation Agency, or Rosaviatsia, seizing documents concerning the activities of numerous aviation training centers suspected of giving out licenses to unsafe pilots.
The searches form part of an inquiry into a plane crash in Kazan on Nov. 17 that resulted in the deaths of all 50 people on board.
Rustem Salikhov, pilot of Tatarstan Airlines' plane that was destroyed, had an aircraft navigation qualification, and then supposedly got a commercial pilot's license from a training center licensed by Rosaviatsia, Investigative Committee spokesman Vladimir Markin said in a statement.
"Investigators doubt the legitimacy of those training centers licensed by Rosaviatsia that are shut at the present time," Markin said, adding that the heads of the relevant Rosaviatsia departments will all be questioned.
"We have reason to believe that a lot of pilots working for small airlines obtained fictitious commercial pilot's license, in so much as they weren't trained," he added.
Tatarstan Airlines said earlier that Salikhov had 21 years of flight experience.
Alexander Neradko, head of Rosaviatsia, said that all pilots who received commercial pilot licenses from dubious training centers will be tested.
New regulations toughening requirements for aviation training centers have already been drafted and sent to the Transportation Ministry, Neradko added.
All 50 victims have now been identified, while blood tests show that the pilots had no alcohol or drugs in their systems at the time of the crash, the statement said.