Let L-410 crash near Gelendzhik

Causes

The investigation was complicated by the fact that the cassette with film was missing from the SARPP-12VM flight recorder. The point is that there was no film at the aviation technical base of Babushera Airport (Sukhumi), so, in accordance with an instruction from the chief engineer of the Georgian Civil Aviation Directorate, the aircraft was cleared for flight with an unloaded recorder. As for the barogram, it burned in the fire.

As was established, on the route the actual height of the stratocumulus and cumulonimbus clouds was 700—1000 metres, there were isolated clouds with a base of 400—500 metres, some mountain peaks were covered by cloud, visibility reached 10-15 kilometres and it was raining. In addition, the wind was in fact 150—170° (south-south-easterly) with gusts up to 12 m/s. Thus, the commission came to the following conclusion. The point is that the calculated heading for proceeding abeam Cape Idokopas was 129°. But with the correction for the wind, which according to the forecast should have been south-westerly, the aircraft's heading should have been 136°, that is, slightly to the right and shifted to the west. It is likely that the pilots took precisely this heading, without taking into account the actual drift and ground speed, otherwise they would have realised that the wind was in fact blowing relative to them not from the right but from ahead. Because of this, the airliner was in fact flying parallel to the shore, deviating to the left of the airway, and somewhere 10—12 kilometres from Gelendzhik it flew into cloud. Having flown in cloud for about one and a half to two minutes, the crew decided that the abeam point of Cape Idokopas had already been passed, and therefore decided, maintaining the heading, to descend below the cloud in order to return to visual flight. During the descent the pilots did not monitor the readings of the radio altimeter, which showed their actual height above the terrain, and after some time the aircraft, flying in cloud 2.7 kilometres (according to other data — 3.7 kilometres) to the left of the airway, crashed into the mountain. Technical examination showed that the airliner had been fully serviceable before the collision with the mountain.

In the conclusion of the commission's report, the cause of the crash was named as an error by the crew, who violated visual flight rules, including failing to keep track of their position, and also descended below the minimum safe altitude established over the terrain being overflown. A contributing circumstance to the crash was that on this route it was not possible to maintain radar control along its entire length, since the capabilities of the radar and radio equipment in use did not allow this when operating on the coast of mountainous terrain.