On 27 March 1977, two Boeing 747s — KLM Flight 4805 and Pan Am Flight 1736 — collided on the runway at Los Rodeos Airport (Tenerife North) in dense fog, killing 583 people and leaving only 61 survivors. What should have been a routine takeoff turned into the deadliest accident in aviation history — and it hinged not just on poor visibility or radio interference, but on a catastrophic collapse of cockpit communication and decision-making.