With 48 aircrafts, Bulgaria has roughly the same number of units than Azerbaijan, and both counties operate Soviet-era jets (mainly MiG-21s and MiG-29s). However, the serviceability and the combat readiness of the aircrafts remain unclear: the flying time for Bulgarian pilots is for instance estimated to 30 to 40 hours a year, and Bulgarian air capacities have been exhausted along 2014 with units regularly scrambling to intercept Russian jets over the Black Sea.