1999
...but the fact is "the slavic" folks as you mentioned them in your post do have a different mentality in that regard primarly because of the "****** up political system" they lived in/for after the 2nd WW....
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Political system has crashed with Gorbachev and Eltsin - USSR collapse made a collapse in everything! - education, SOPs etc
Now about the topic:
1. The wing profile of soviet airplanes is much thicker then westerns! That's why it is permitted to have some DRY snow on a wing of "russian" airplane - it is not so vital like for CRJ for example. And that should be explained to ex-soviet drivers!
2. According UTair SOPs - the technician at base airport is responsible to check the contaminant on a wing and inform the captain about....
3. Anyway final decision shall be made by Captain - desicion was wrong.......