All new fog radar, and auto approach... not had a single problem with Sofia this season... unless you count waiting an extra half hour while they cleared a bay from snow, to disembarke...
Seen them land and take off in 25cm of snow... no problem...
Unlike the roads
So if it is snowy, planes are likely to be able to land but the transfer coach might take an age to get to Bansko. How good ar the Bulgarians at keeping the resort roads open?