 The MiGs took off from the Dobroslavtsi airport, and were responsible for the defense of the capital city of Sofia.According to pilots Petrov and Sankiisky, Sankiisky first attempted to warn the El Al plane that it was in violation, by shooting signal rounds in front of the Constellation's nose; Petrov repeated the warning.In the meantime, the El Al plane neared the southern border of Bulgaria with Greece and the near-border city of Petrich, where it was shot down.