Russian officials say alcohol and pilot confusion over the instrument panel on a Boeing passenger jet were responsible for last year's crash that killed 88.
The Boeing 737-500 operated by an Aeroflot subsidiary crashed Sept. 14 while preparing to land in the city of Perm, about 1200 kilometers (750 miles) east of Moscow.
Russia's airline investigator, the Interstate Aviation Committee, said in its final report, released on its Web site Tuesday, that the plane's captain "lost spatial orientation" after he misread an attitude indicator on the Boeing's instrument panel. The attitude indicator indicates whether a pilot is flying straight and level.
"That led to a banking of the plane onto its left wing, and its entering into an intensive descent and collision with the ground," the report said, adding that the nighttime landing and clouds exacerbated the flying conditions.
Alcohol detected in body
The committee also said an unspecified amount of alcohol was detected in the pilot's body, and that he was overworked.
The subsidiary, Aeroflot-Nord, had given the pilots insufficient training on how to read the attitude indicators on foreign jets, the committee said. The attitude indicator is designed differently on Soviet-made planes and Western airliners.
The committee said experts from the United States, Britain and France helped compile the report.
Russia's aviation authority had suspended flights aboard Boeing 737s until their pilots received additional training.
Perm flight controller Irek Bikbov said in remarks broadcast by state-run Channel One television on the day of the crash that the plane's pilot was behaving strangely, disobeying orders to descend on the final approach and instead taking the jet to a higher altitude.
Bikbov said he then ordered the pilot to make a second run, but instead of making the right turn he turned left. When the controller asked the pilot if things were normal on board, the pilot answered positively.
Aeroflot, Russia's largest carrier, severed links with the subsidiary immediately after the crash, ordering all the company's branding removed from Aeroflot-Nord's fleet.