The small size of Bulgaria defines the small portion of free airspace (class G). Despite that, the traffic in the country is not heavy and allows for free tasking of more than 500 km. Biggest free airspace is positioned in NE Bulgaria.
The country has 5 major civil airports with permanently activated control zones. The 2 major military airports work with temporarily separated zones. The busiest traffic in the country is concentrated in central West Bulgaria (Sofia airport – LBSF) and Eastern Bulgaria (Varna and Bourgas Airports – LBVN, LBBS). In spring time many temporary danger zones get activated in central and NW Bulgaria on thunderstorm days by the national weather modification agency (hail prevention).
The map below marks the biggest and most active airports and main controlled zones in the country.
To get information about the current active airspace you can check the official Airspace Usage Plan