Sofia airport's catagory has been updated to enable flights to land under certain foggy conditions which is great news.
Link to the article here; http://www.novinite.com/view_news.php?id=98044
I'm sure i read terminal 1 and T2 use different runways,and only 1 of the runways is fitted with the foggy thingy landing whatsyoucallit...All sheduled flights like BA etc use the new system whilst all charters use a different runway..
If it's foggy and a plane is coming down with a visability of 200 meters then i am sure they will use the runway with the new gear rather than flying to Greece or Plovdiv.