Translation of bits of posts from the accident thread on a Russian pilots’ forum that seem to make sense:
Regarding GA:
FMS on a 735 is designed to hook on to VOR/DME beacons, which are very few in Russia. In Perm, there is actually none. As a result, by the time they approached Perm from Moscow, significant error in location identification has built up. Even if there was GPS onboard, it is known for grossly erroneous readings over Russian territory. GLONASS, Russian analogue of GPS, has not yet been deployed.
There is no ILS with heading 32 in Perm, only ILS 212.
So, of all the miracles of navigation, only ADF, a technology from the 1930’s, might have remained of use onboard that plane. In a 2-man crew, without the navigator, it might be a hell of a job to do an IMC approach at night using only one set of ADF.
Captain’s request for the 212 approach heading is an indication of attempted ILS landing.
Regarding sudden climbing turn to the left:
There are hills to the east of Perm. When shooting a 32 ILS, they are seen forward right. So if GPS was mispositioned it could send a warning of close terrain and prompt the captain to turn left.
Regarding captain’s behaviour:
1)He requested heading 212 because this was the easiest mode of approach for him and he felt unconfident about other headings.
2)He botched up reporting his position to the ATC controller at some point during the approach and did not want to admit to the controller that he lost his orientation.
3)Because of loss of situational awareness he misinterpreted instructions of the controller as he could no longer figure out where was right and left.
4)His control inputs (nose up instead of nose down) is indication of his struggle with the loss of speed and look more like hectic actions then indented maneuver.
5)Captain’s actions are indicative of his desire to conceal the mistakes characteristic for a trainee.
6) Captain was in the home-itus state, which urged him to get on the ground as soon as possible instead of making a standard GA, which he was afraid of doing (because of night, rain, dark, no lights on the ground, loss of SA)