On October 9, 1976, a catastrophic mid-air collision occurred near Zagreb, Yugoslavia, involving a British Airways Hawker Siddeley Trident and an Inex-Adria DC-9. The Trident, operating on a flight from London to Zagreb, was preparing to land when it struck the DC-9, which was flying from Split to Zagreb. Both aircraft entered a dense fog layer as they approached the airport, leading to reduced visibility. The crew of the Trident was allegedly cleared to descend, while the DC-9 was also navigating a similar descent, although unaware of the Trident's position. The resulting collision resulted in the tragic deaths of all 176 passengers and crew members aboard both planes, marking one of the most severe aviation disasters in the region's history. First responders faced significant challenges due to the wreckage being spread over a broad area, highlighting difficulties in emergency response during such disasters.

The aftermath of the collision led to an extensive investigation by Yugoslav authorities, which revealed systemic communication failures within air traffic control. Air safety protocols were reassessed, and recommendations were made to improve pilot training and communication standards in Eastern European aviation. This incident underscored the importance of stringent safety measures in air travel and prompted changes in international aviation regulations as safety continued to evolve during the late 20th century.