The twin-engine Antonov An-28 was attempting to make an emergency landing in September in Russia's far eastern Kamchatka Peninsula when it went down in a wooded area, RIA Novosti reported.
Kamchatka's special programs minister said the plane was on a flight from the regional capital Petropavlovsk-Kamchatsky to an airfield in the village of Palana when it lost contact with air traffic control.
"The An-28 pilots violated the landing approach pattern and transmitted incorrect data to the air traffic control services on how the flight was being carried out, according to the conclusions of the Interstate Aviation Committee," said Anton Artyomenko, Kamchatka Region Transport Investigation Department head. "Ethyl alcohol was found in the crew's blood."
One pilot had a blood alcohol consistent with a hangover and the other had level the Interstate Aviation Committee described as "consistent with being a medium level of alcoholic intoxication."
There were no technical faults with the airplane, Novosti reported.
The plane was carrying 12 passengers, two of them children, and a crew of two when it crashed. Four people survived, including one child.