What happened
During a nighttime cargo operation traveling from Beirut toward Tehran, a four-engine aircraft was targeted by the pilot of an unidentified fighter jet while cruising at an altitude of approximately 13,000 to 15,000 feet. The attack resulted in damage to the first engine, which ignited a fire that subsequently spread to the wing and the nacelle.
Following this incident, the fourth engine was shut down and the propeller was feathered due to the depletion of fuel in its tank. Facing these critical mechanical failures, the crew initiated a descent to a lower altitude and sought an emergency landing site in the vicinity of Rasht. The aircraft eventually reached a field where it came to a stop; while the airframe was destroyed, all three crew members escaped without injury.
Findings
Investigations into the incident suggest that the flight path may have deviated due to a navigation error, which resulted in the aircraft entering Soviet airspace without proper authorization. The primary cause of the damage was the direct strike from an unknown fighter aircraft.