Tenerife Airport Disaster: A Fatal Human Error

The Tenerife Airport Disaster, which occurred on March 27, 1977, is considered the worst accident in commercial aviation history, resulting in the tragic loss of 583 lives. The collision between two Boeing 747 jumbo jets from Pan Am and KLM on the runway of Los Rodeos Airport was caused by a combination of factors, including radio interference, poor visibility due to fog, inadequate airport infrastructure, and human error. The investigation that followed led to significant changes in aviation safety practices and regulations, with a renewed focus on standardising radio communications and improving crew training and management.

Radio interference between the two aircraft and air traffic control

On 27 March 1977, two Boeing 747 passenger jets, KLM Flight 4805 and Pan Am Flight 1736, collided on the runway at Los Rodeos Airport on the Spanish island of Tenerife. The incident, which occurred at 5:06 pm in dense fog, resulted in a total of 583 fatalities, making it the deadliest accident in aviation history.

The disaster was caused by a combination of factors, one of which was radio interference between the two aircraft and air traffic control. The air traffic controller, who could not see the runway due to the fog and lacked ground radar, responded with “OK” to the KLM first officer's non-standard statement that they were “now at takeoff”. This response reinforced the KLM captain's misinterpretation that they had received takeoff clearance. However, the controller's use of "OK" was likely due to his misinterpretation of the first officer's statement, assuming they were in the takeoff position and awaiting clearance, rather than initiating the takeoff roll.

Immediately after, the controller added, "Stand by for takeoff; I will call you", indicating that he had not intended to grant takeoff clearance. Unfortunately, a simultaneous radio transmission from the Pan Am crew caused interference on the frequency, resulting in a three-second-long shrill sound in the KLM cockpit. This interference prevented the KLM crew from clearly hearing the controller's instruction not to take off and the Pan Am crew's transmission that they were "still taxiing down the runway".

The disaster highlighted the critical importance of using standard phraseology in radio communications. As a result, changes were made to cockpit procedures, including the establishment of crew resource management as an essential part of airline pilots' training. It is now recognized that the captain is not infallible, and combined crew input is encouraged during aircraft operations.

The investigation into the accident also revealed that the airport was overwhelmed by the number of large aircraft rerouted due to a bomb explosion at Gran Canaria Airport. The increased traffic led to congestion, with planes parked on the taxiway, and visibility was further reduced by the fog. These factors, along with the radio interference, contributed to the tragic outcome of the Tenerife airport disaster.

Foggy conditions at Los Rodeos Airport

On March 27, 1977, two 747 passenger jets crashed on a runway at Los Rodeos Airport on the Spanish island of Tenerife, killing 583 people. This tragic incident, known as the Tenerife Airport Disaster, was the result of a combination of factors, including foggy conditions, communication breakdowns, and human error. Here, we will focus on the role of the foggy conditions at Los Rodeos Airport and how they contributed to the disaster.

Los Rodeos Airport is situated at an altitude of 610 meters, which makes it prone to cloudy and foggy conditions. On the day of the accident, thick fog had enveloped the airport, reducing visibility significantly. This was not an uncommon occurrence due to the airport's altitude and the influence of the nearby volcano, Mount Teide, on local weather conditions. The fog drifted across the airfield, causing variable visibility conditions that affected both the flight crews and the air traffic control tower.

The Pan Am aircraft, which was larger and had been struggling to navigate the airport due to its lack of familiarity with the layout, had less than 100 meters of visibility on the runway. Meanwhile, at the other end of the runway, the KLM aircraft initially had good visibility when it started its takeoff roll. However, clouds were moving towards it down the runway, reducing its visibility as well.

The foggy conditions severely limited the ability of both flight crews to accurately identify their positions on the runway. This misidentification of positions was a critical factor that led to the collision. The KLM crew's decision to initiate takeoff without proper clearance, combined with the limited visibility, resulted in the two aircraft colliding near the runway fourth exit.

The dense fog also impacted the air traffic control tower's ability to monitor the aircraft's movements effectively. The tower's view was obscured by the fog, making it challenging for them to provide accurate instructions and ensure the safe operation of the flights. The combination of foggy conditions, communication breakdowns, and human error ultimately led to the tragic outcome of the Tenerife Airport Disaster.

The airport's limited capacity and infrastructure

The Tenerife Airport disaster was caused in part by the limited capacity and infrastructure of the Los Rodeos Airport. The airport was small and had only one runway and one major taxiway, with four short taxiways connecting the two. This limited infrastructure meant that the airport could not easily accommodate all the traffic that had been diverted from Gran Canaria Airport due to a terrorist bombing. The diverted aircraft were forced to park on the main taxiway, which further reduced the space available for departing aircraft. This congestion led to delays and increased the risk of accidents.

The limited capacity of the airport was further exacerbated by the fact that there were only two air traffic controllers on duty that day. They were forced to handle much more traffic than the airport had ever seen, which likely contributed to the confusion and miscommunication that led to the disaster. The airport's single runway and taxiway also meant that there was a higher risk of aircraft colliding if they were not properly coordinated during takeoff and landing.

The foggy weather conditions on the day of the accident further reduced visibility and made it even more challenging for pilots and air traffic controllers to safely manage the high volume of aircraft. The thick fog may have contributed to the Pan Am crew's struggle to locate the exit taxiway, leading them to miss it and continue down the runway. The acute angle of the exit taxiway may have also made it difficult for the large aircraft to turn off the runway, even if they had managed to locate it in time.

The limited infrastructure and capacity of Los Rodeos Airport, combined with the high volume of diverted traffic, congested conditions, and reduced visibility due to fog, created a perfect storm that contributed to the tragic outcome of the Tenerife Airport disaster. This disaster highlighted the importance of having adequate airport infrastructure and capacity to handle unexpected events and ensure the safe and efficient management of air traffic.

The Pan Am crew's unfamiliarity with the airport

The Tenerife Airport Disaster, which occurred on March 27, 1977, was a result of several unfortunate events, including the Pan Am crew's unfamiliarity with the airport. The crew's lack of knowledge about the airport layout and procedures contributed significantly to the tragedy.

As the Pan Am crew taxied down the runway in dense fog, they struggled to locate the correct exit. The third exit, which they were instructed to take, was challenging to identify due to the limited visibility. The crew's charts indicated that the third exit required a series of sharp turns that their Boeing 747 could not easily navigate. This confusion over the exit likely contributed to the crew missing their turn and continuing down the runway, ultimately leading to the collision with the KLM 747 that was taking off.

The unfamiliarity of the Pan Am crew with Los Rodeos Airport extended beyond just the runway exits. The airport was not designed to accommodate such a large volume of air traffic, especially not five large airliners that had been rerouted due to the terrorist incident at Gran Canaria Airport. This congestion further complicated operations and likely added to the crew's confusion and disorientation.

Human error and the pressure to avoid exceeding duty-time limits

The Tenerife Airport Disaster, which occurred on March 27, 1977, is considered one of the worst aviation disasters in history, claiming the lives of 583 people. The crash occurred when two 747 passenger jets, a Pan Am aircraft and a KLM 747, collided on a runway on the Spanish island of Tenerife. The investigation that followed was the first of its kind to consider human error as a contributing factor.

One of the key factors in the disaster was the pressure on the KLM captain, Jacob Veldhuyzen van Zanten, to avoid exceeding duty-time limits. The KLM flight had been diverted to the smaller Los Rodeos Airport on Tenerife due to a terrorist incident at its original destination, and the diversion caused a delay that put the flight at risk of exceeding its duty-time limit. Van Zanten felt the pressure of wanting to avoid this, and so when he believed he had clearance to take off, he initiated the takeoff roll, even though he had not received proper clearance from air traffic control.

The interference caused by a simultaneous radio message from the Pan Am aircraft also contributed to the tragedy. The Pan Am crew had indicated that they were still taxiing down the runway, but this message was not heard by the KLM crew due to the interference. As a result, the KLM aircraft began its takeoff roll, and the two planes collided.

The investigation and subsequent reviews of cockpit procedures highlighted the importance of standard phraseology in radio communications. It was recommended that specific phrases, such as "takeoff," should only be used in certain contexts, and that non-standard responses, such as "OK," should be avoided. The investigation also led to changes in crew training and management, encouraging a more collaborative approach and empowering all crew members to challenge decisions, regardless of seniority.

The pressure to avoid exceeding duty-time limits, combined with human error and communication issues, were significant factors in the Tenerife Airport Disaster. This tragic event had a lasting impact on the aviation industry, leading to important safety changes and a stronger focus on incident prevention.

Frequently asked questions