MOSCOW (AP) — A commission investigating last year's crash of a plane that killed 92 people including members of Russia's renowned army choir says it may have been caused by pilot disorientation.

The Defense Ministry's Tu-154 crashed into the Black Sea about a minute after takeoff from Sochi on Dec. 25, killing all aboard.

State news agency Tass on Wednesday cited the ministry as saying the commission found that "the crash could have been caused by spatial disorientation (situational unawareness) of the pilot." It didn't elaborate on that suggestion. It also ruled out "external factors." Officials said previously there was no evidence of an explosion on board.

Among the dead were members of the Alexandrov Ensemble, widely called the Red Army Choir, who were to perform at a Russian base in Syria.