On 27 March 1977, an otherwise quiet Sunday in Tenerife, Spain 's Canary Islands, was shattered by an unprecedented aviation tragedy. Two Boeing 747 jumbo jets, KLM Flight 4805 and Pan Am Flight 1736, collided on a fog-covered runway at Los Rodeos Airport (now known as Tenerife North Airport), leading to the deadliest accident in aviation history. The incident left a profound mark on aviation safety protocols and procedures worldwide. The Chain of Events Begins: Gran Canaria