What happened
Two commercial airliners, a McDonnell Douglas DC-10 operated by VIASA as Flight 800 and an Airbus A310 operated by Pan American World Airways as Flight 221, were involved in a serious near collision while traversing the Atlantic Ocean. Both aircraft were flying on international airways, specifically Amber 300, under instrument flight rules (IFR). The airspace was non-radar, meaning there was no direct radio contact between the pilots and air traffic control facilities; instead, communications were relayed through ARINC, a commercial aeronautical communications company.
The incident began when Flight 221, traveling southbound at flight level 370, submitted a request via ARINC to climb to flight level 390. The oceanic controller at New York Center received this request and coordinated with the San Juan Air Route Traffic Control Center. After scanning his sector board for potential conflicts, the controller found none and approved the altitude change.
Once Flight 221 leveled off at flight level 390, it converged head-on with Flight 800, which was traveling northbound at the same altitude. The crew of Flight 800 detected the conflict and took immediate evasive action, while the crew of Flight 221 elected not to maneuver. The captain of Flight 800 later estimated that the two aircraft passed each other with a horizontal separation of between 500 and 1,000 feet and a vertical separation of approximately 350 feet.
Contributing to the situation was the fact that the controller had just come on duty. Additionally, Flight 800 had previously passed a mandatory reporting point, leading the controller to remove its flight strip from his board because the next intersection was a non-reporting fix. This lack of visual tracking in a high-density oceanic corridor created the conditions for the near miss.