The fatal crash of a RusAir Tupolev Tu-134A at Petrozavodsk, northern Russia, in June 2011 was caused by the failure of the crew to execute a go-around in poor weather, together with poor crew resource management and a mildly drunk navigator.
The 20 June accident in which 47 of the 52 passengers and crew died - one of a series of crashes in Russia this year - triggered a demand by President Dmitry Medvedev that Tu-134s should be removed from scheduled service. Around 90 are still in airline service in the country.
The official report into the Petrozavodsk crash by Russia's Interstate Aviation Committee says that the main reason for the accident was the failure of the crew to go around and their descent below the minimum safe altitude in the absence of any visual contact with either the approach lights or landmarks.
Weather at the time of the crash - 23:40 local time - was poor. Although still twilight at that time in such a northerly latitude, around 400km (248.5mi) northwest of St Petersburg, there was heavy rain and fog in the area.
Contributory factors, said investigators, included poor communication and a lack of crew resource management by the captain as he made the approach. The navigator had "a mild degree of alcoholic intoxication" and was "increasingly active" during the approach, while the co-pilot seemed to have been out of the command loop.
The aircraft, registration RA-65691, crashed into trees in controlled flight, some 270m (885.8ft) offset to the right of the airport's single 2,500m runway, and burned fiercely.