A Dan-Air Boeing 727 carrying British tourists to the Canary Islands crashes and kills all 146 on board on this day in 1980. This terrible crash came just three years after another even deadlier accident at the Canary Islands airport.

In 1977, a KLM jumbo jet had collided with a Pan Am plane on the runway; 570 people were killed. The collision occurred when communication problems between the planes and air-traffic controllers exacerbated already dangerous foggy conditions. The heavily accented English spoken by the Spanish-speaking air traffic controllers was partly to blame.

On April 25, 1980, similar problems at the same airport had tragic results. It was late morning and cloudy when a chartered jet arrived from Manchester, England. The plane was carrying 138 passengers, bound for the beaches of Tenerife, and 8 crew members. Inaccurate navigation by the pilots set the tragedy in motion; they told the air traffic controllers that they were a mile east of their actual position.

The airport did not have radar capabilities at the time and cleared the plane to descend to 6,000 feet and wait to be assigned a landing area. Over the next critical moments, the plane’s crew and the air traffic controllers had difficulty communicating regarding the plane’s location and how they should proceed. Finally, the pilot, confused by an order he had been given by the air-traffic controllers, turned the plane directly toward the mountains on the small island.

Due to the intensely cloudy conditions, the pilots never saw the mountain directly in front of them. All 146 people were killed on impact when the jet crashed directly into the side of a mountain.