On March 27, 1977, the worst disaster in aviation history occurred in what was known as the Tenerife Airport Disaster. As a result of an over-crowded airport, poor weather conditions, and a failure to communicate between air traffic control and the crew of one of the flights, two Boeing 747 planes would collide on the tiny airport’s only runway, killing 583 people.
A perfect storm of panic, congestion, confusion and poor visibility, looking back, the disaster seems nearly almost inevitable.
To date, the Tenerife Airport Disaster remains the deadliest disaster in aviation history.
“Most people have never heard of Tenerife, a pan-shaped speck in the Atlantic. It’s one of the Canary Islands, a volcanic chain governed by the Spanish, clustered a few hundred miles off the coast of Morocco. The big town on Tenerife is Santa Cruz, and its airport, beneath a set of cascading hillsides, is called Los Rodeos. There, on March 27, 1977, two Boeing 747s — one belonging to KLM, the other to Pan Am — collided on a foggy runway. Five hundred and eighty-three people were killed in what remains the biggest air disaster in history. The magnitude of the accident speaks for itself, but what makes it particularly unforgettable is the startling set of ironies and coincidences that preceded it. Indeed most airplane crashes result not from a single error or failure, but from a chain of improbable errors and failures, together with a stroke or two of really bad luck. Never was this illustrated more calamitously, and almost to the point of absurdity, than on that Sunday afternoon over 30 years ago,” explains NYC Aviation.
Here’s what you need to know.
1. Terrorists Struck a Nearby Airport
The morning of March 27, 1977, a bomb was detonated in a gift shop at the Las Palmas de Gran Canaria Airport located in the Canary Islands, injuring eight people. The bomb, believed to be the work of terrorists, caused all planes to be diverted to nearby airports. The majority of flights went to the nearby Los Rodeos Airport (now known as the Tenerife North Airport), a small space not equipped to handle the large amount of planes it would soon be inundated with.
After a subsequent investigation, blame was placed on the Canary Islands Independence Movement (CIIM). The CIIM is allegedly responsible for several other violent attacks in and around the Canary Islands. The CIIM was reportedly resorting to violent measures to force the government of Spain to grant independence to the Canary Islands.
The CIIM was allegedly active from 1975-1980. 31 separate attacks have been attributed to the CIIM. The CIIM is also known as the Movement For The Independence And Autonomy Of The Canaries Archipelago. More information can be found at the Global Terrorism Database.
2. Los Rodeos Soon Became Extremely Crowded & Well Over Its Capacity
“While the aircraft were en route to Las Palmas, a bomb exploded in the passenger terminal building at the airport. Due to the threat of a second explosion, the terminal building was evacuated and the airport closed. Much of the traffic arriving at Las Palmas Airport was diverted to Los Rodeos (Tenerife) Airport on Tenerife Island. For this reason, the parking area at the latter airport was crowded with airplanes,” explains the FAA
As a result of the explosion at the Las Palmas de Gran Canaria, pilots scrambled to divert their planes as the airport went into shutdown mode. One of the closest was Los Rodeos Airport, also located in the Canary Islands. Unfortunately, Los Rodeos was much too small to handle such a large number of planes, and it soon became more of a parking lot than a runway.
Planes sat, unmoving, for several hours. Passengers were agitated, uncomfortable and thirty. Flight crews were not allowed to let the passengers out of the cabins. It was too dangerous due to the poor visibility outside to allow alone to deplane. As such, they stayed, unmoving, for hours.
“Once the Las Palmas Airport had been reopened, the Pan Am crew prepared to proceed to Las Palmas. However, when they attempted to taxi to the runway, their path was blocked by the KLM airplane which, unlike the Pan Am airplane, had allowed its passengers to leave the aircraft during the delay time on the ground. All aircraft were also unable to use the parallel taxiway on account of the aircraft congestion on the main apron. The three other airplanes parked in front of the KLM airplane had already departed,” the FAA notes.
3. As a Result of Dense Fog, Visibility Was Near Zero
The airfield was covered with an unusually thick, dense fog on March 27, 1977. As a result, visibility was near zero. Between the fog and the congestion of aircraft, confusion was high.
Visibility was so poor, in fact, that when the KLM pilot thought he was cleared for takeoff, he could not see the Pan Am plane that was still taxiing down the runway.
The official accident report, detailing the weather conditions that contributed to the accident is available here. Reportedly, it is not unusual for blankets of fog to cover the Tenerife Airport; but it usually dissipates quickly.
4. A Miscommunication Caused The Pilot of KLM Flight 4805 to Believe He Was Clear For Takeoff
A failure to understand commands from the air control tower contributed to the confusion of the pilot of KLM Flight 4805. Believing he was cleared for takeoff, he proceeded down the incorrect path, heading toward the Pan Am plane, which was still taxiing.
“Eventually Pan Am’s 747 was cleared to leave, but before doing so – and because of congestion blocking the normal taxi route – it was told to move down the runway and wait in one of the exits. Once the preceding departure – operated by KLM – had left, it could continue its journey to the end of the runway. Unable to find the correct exit in the fog, the Pan Am pilots missed their waiting zone. Meanwhile, the KLM jet, failing to understand commands from the control tower, began barrelling down the runway in the opposite direction. By the time the two pilots spotted each other, it was too late. The Pan Am captain, Victor Grubbs, made a futile attempt to veer off the runway; Jacob Van Zanten tried to take off, but the undercarriage and engines of KLM’s 747 sliced into the top of the other jet. The KLM plane hit the ground 150 metres beyond the point of collision, and slid down the runway for a further 300 metres. Fire engulfed it before any of its 268 passengers could escape. The Pan Am jet, meanwhile, was completely torn apart,” explains The Telegraph.
When the collision occurred, both 747s burst into flames. There would only be 61 survivors. The rest would die trapped inside a raging inferno. The KLM plane had shorn the top of the Pan Am plane off, like opening a can. Jet fuel spread everywhere, causing the fire to spread quickly and furiously.
“The KLM plane had peeled off the top of the Pan Am plane, just like peeling off the top of a sardine can, the top had rolled right off. Everyone in the top section had gone. There was nothing around that looked like anything had looked before – just jagged metal and small pieces of debris,” reported The Telegraph.
A transcript of all communications between the pilots and the air control center is available here, courtesy of the FAA.
5. A Massive Review of Aviation Procedures Would Follow, Resulting in Drastic Changes to The Industry
A major investigation into the events that transpired on March 27, 1977 would take place. While it was largely agreed that many contributing factors could not have been foreseen or prevented, such as the terrorist attack at the Gran Canaria and the unusual amount of fog, KLM ultimately accepted responsibility for the disaster.
It was determined that a series of miscommunications between the KLM pilots and the air traffic control tower ultimately led to the KLM pilots believing that they were cleared for takeoff. According to investigators, there were numerous “mutual misunderstandings” between KLM and air traffic control.
KLM paid financial compensation to the families of the victims of the disaster. The industry would undergo several changes as a result of the investigation, including using standardized phraseology in radio communications. All cockpit procedures would be reviewed, and crew resource management would be established.
Today, a memorial stands at the site of the disaster to honor the 583 lives that were lost in 1977.
CORRECTION: An earlier version of this post incorrectly listed the date of a bomb that was detonated Las Palmas de Gran Canaria Airport in the Canary Islands. The incident happened on March 27, 1977, not March 27, 2017.