Balkan Bulgarian Airlines Flight 107

Balkan Bulgarian Airlines Flight 107 was an accident that occurred on 16 March 1978, when a Tupolev Tu-134 operated by Balkan Bulgarian Airlines crashed on an international flight from Sofia Airport to Warsaw Airport. All 73 passengers and crew died in the crash (66 passengers and a crew of 7). As of 2026, it remains the deadliest accident in Bulgarian aviation history. The exact cause of the crash remains unknown.

A 2024 investigation by "Biograph" journal found witnesses in former communist Committee for State Security (DS) who testified that the aircraft had two unlisted passengers, who were most likely DS-trained agents from Arab countries. The aircraft was most likely hijacked in-flight and crashed as a result of onboard fighting, neither of which the communist government was ready to admit.

Accident

On departure from Sofia, flight LZ 107 began to climb to 8850 m but at 4900 m, it turned on a heading of 050 degrees. It turned again to 270 degrees before it began an abnormal descent. The aircraft crashed 10 minutes from takeoff near the village of Gabare, close to Byala Slatina, 130 km northeast of Sofia, killing all 73 people on board. At the time of the crash, the aircraft was flying at a speed of 800 km/h with almost full fuel tanks, containing 11 tons of fuel. The nature of the emergency and whether the aircraft was under control at the moment of impact were never established.

After the crash, the Bulgarian Army quickly arrived at the scene, and sealed it off. The investigation performed afterwards was superficial. The official cause given by the Bulgarian authorities was a "malfunction of electrical installation". The accident was quickly forgotten, with no further investigations being conducted. The haste with which the disaster was "forgotten" and the superficial investigation that was carried out raised doubts. This sparked speculation as to the real cause of the crash. One version of the event claimed that the Tu-134 collided with a MiG-21 of the Bulgarian Air Force. Another version assumed that the aircraft was shot down mistakenly by the Bulgarian anti-aircraft defense system. These claims are driven by the fact that there was a Warsaw Pact military base in the area.