Monday marks the anniversary of the deadliest aviation accident in history

Fog played a role in the disaster that killed 583 people

March 27, 1977- A KLM Royal Dutch Airlines Boeing 747 crashes into a Pan American World Airways Boeing 747 at the Los Rodeos Airport at Tenerife in the Canary Islands, killing 574 people (326 passengers on the Pan American airplane and all 234 passengers plus 14 crew members on the KLM plane).

The worst aviation crash in history took place 46 years ago on the small Atlantic island of Tenerife. In total, 583 people lost their lives in a crash that was caused by a disastrous chain of events, poor communication, and fog.

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This particular crash is one that would change the course of aviation forever, with major updates to how pilots communicate and how chains of command are handled. But, how could something like this happen? As with most disasters, there were multiple causes. The disastrous chain of events was set forward by a bomb at an airport. Weather also would play a role.


The incident involved two massive planes — both Boeing 747 passenger jets. One was a KLM flight, A Dutch airline flying from Amsterdam, carrying 235 passengers and 14 crew members. The second was an American Pan Am flight, originating in Los Angeles, carrying 380 passengers and 16 crew members.


Both flights were scheduled to land in the Canary Islands at Grand Canaria Airport. Shortly before their arrival, a bomb exploded at the airport, planted by separatists who wanted independence for the islands from Spain. The bomb injured eight people. A second bomb threat was called into the airport, setting in motion a deadly chain of events. The airport was subsequently closed to air traffic, and both flights were re-routed to the island of Tenerife at Los Rodeos airport, a smaller commuter airport.


The airport was small and because so many planes were waiting, the taxiways were full. It required planes to taxi the runway and then turn around on the same runway for takeoff. Once the bomb threat had cleared, planes began to leave the Los Rodeos airport. In the meantime, fog had settled in over the airport, which frequently experienced visibility issues. At this point, visibility was significantly reduced.


Initially, the Pan Am flight was instructed to take off before the KLM flight. However, the KLM plane was refueling and in the way. The Pan Am flight couldn’t get by and had to wait. Once refueled, air traffic control instructed the KLM flight to taxi down the runway and then make a full flip to come back down the runway to take off. While the KLM flight was getting in position, the Pan Am flight was instructed to taxi down the runway, as well. Miscommunication and interference between air traffic control and both planes caused further issues. The KLM pilot mistakenly believed they were clear for takeoff, even though the co-pilot and engineer expressed concern. The Pan Am pilots were also having issues understanding which taxiway to take, so they could exit the runway. With the fog, neither plane could see the other until it was too late. The two planes collided, with the KLM flight moving at takeoff speeds (around 160 mph). The KML plane clipped the Pan Am flight and the collision resulted in a massive explosion.


Sadly, 583 passengers died from the collision. Only 61 crew and passengers aboard the Pan Am flight survived. The crash sparked an intensive investigation, in which several issues were discovered. Fog was determined to be a major factor in the incident. Sweeping changes in commercial aviation took place after the crash, including updates to how communication between pilots and air traffic control takes place. It also called for flight crews to speak up to the captain of a plane should they see something wrong. It remains the deadliest commercial aviation accident of all time.

About the Author

Justin Horne is a meteorologist and reporter for KSAT 12 News. When severe weather rolls through, Justin will hop in the KSAT 12 Storm Chaser to safely bring you the latest weather conditions from across South Texas. On top of delivering an accurate forecast, Justin often reports on one of his favorite topics: Texas history.

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