Survivors Of The Tenerife Airport Disaster: A Fateful Day

On March 27, 1977, two Boeing 747 passenger jets, KLM Flight 4805 and Pan Am Flight 1736, collided on the runway at Los Rodeos Airport (now Tenerife North Airport) on the Spanish island of Tenerife, killing 583 people in the deadliest accident in aviation history. All 248 people on board the KLM plane perished, while 335 of the 396 people on the Pan Am plane died, leaving only 61 survivors, mostly from the front section of the aircraft.

The KLM captain's decision to take off without clearance

The Tenerife airport disaster, which occurred on March 27, 1977, was a result of multiple factors, but a key cause was the KLM captain's decision to initiate the takeoff without clearance from the control tower.

Captain Jacob Van Zanten, who was KLM's top pilot, head of safety, and chief flight instructor, faced a challenging situation at Tenerife's Los Rodeos Airport. The airport was congested due to diverted flights, including his own, following a terrorist bombing at the intended destination, Gran Canaria Airport. The small size of the Tenerife airport and the dense fog that had settled in further complicated the situation.

As the fog temporarily lifted, Captain Van Zanten, feeling pressured by the strict duty time limits imposed by the Dutch government and concerned about the worsening weather conditions, decided to take off. However, he had not received final takeoff clearance from the control tower. The first officer, Klaas Meurs, noted that they didn't have clearance, and Van Zanten asked him to get it. Miscommunication and confusion ensued, with Van Zanten believing that they had been cleared for takeoff.

As the KLM plane started its takeoff roll, the flight engineer, Willem Schreuder, expressed concern, asking, "Is he not clear then?" referring to the Pan Am plane still on the runway. Van Zanten replied, "Oh, yes," even though the Pan Am flight was still taxiing down the runway. Due to the fog, neither crew was able to see the other plane, and the lack of ground radar at the airport meant that the control tower couldn't see them either.

The KLM plane picked up speed and emerged from the fog just as the Pan Am plane was turning onto the exit ramp. Realizing his mistake, Van Zanten tried to take off early but was too low. The KLM plane collided with the Pan Am plane, resulting in a catastrophic disaster that claimed the lives of all 248 people on board the KLM aircraft and 335 out of 396 on the Pan Am flight.

Investigations concluded that the primary cause of the accident was Captain Van Zanten's decision to take off without clearance, influenced by the desire to depart as soon as possible to comply with duty-time regulations and beat the worsening weather. The disaster had a lasting impact on the aviation industry, emphasizing the critical importance of standard phraseology in radio communications and the need for crew resource management and mutual decision-making during aircraft operations.

Radio interference and non-standard phrasing

The Tenerife Airport Disaster, which occurred on March 27, 1977, is considered the deadliest accident in aviation history. Two Boeing 747 passenger jets, KLM Flight 4805 and Pan Am Flight 1736, collided on the runway at Los Rodeos Airport, resulting in 583 fatalities. The primary cause of the accident was the decision of the KLM captain, Jacob Veldhuyzen van Zanten, to initiate the takeoff without receiving formal clearance from air traffic control (ATC). This decision was influenced by a desire to depart promptly and a misunderstanding of radio communications with the ATC.

Mutual Interference:

A simultaneous radio transmission from the Pan Am crew caused mutual interference with the ATC's response to the KLM crew. This interference resulted in a three-second-long whistling sound in the KLM cockpit, blocking the crucial latter portion of the ATC's message. The Pan Am crew's transmission, "We're still taxiing down the runway, the Clipper 1736!", was also inaudible to the KLM crew due to the interference. Either message, if heard, would have alerted the KLM crew to the Pan Am aircraft's presence on the runway, allowing them to abort the takeoff attempt.

Non-Standard Phrasing:

The ATC's use of the word "OK" in response to the KLM crew's statement, "We are now at takeoff," was non-standard phrasing. This response reinforced the KLM captain's misinterpretation that they had received takeoff clearance. The ATC's full message, "OK, Standby for takeoff, I will call you," indicated that takeoff clearance had not been granted, but the KLM crew only heard "OK" due to the interference.

Ambiguous Communication:

The ATC's instruction to the Pan Am crew to "report the runway clear" was ambiguous and contributed to the confusion. The KLM flight engineer asked the KLM pilots, "Is he not clear, that Pan American?" referring to the Pan Am aircraft. The KLM captain emphatically replied, "Oh, yes," indicating his belief that the runway was clear, despite the Pan Am aircraft still taxiing on it.

Lack of Standard Phraseology:

The investigation highlighted the vital importance of using standard phraseology in radio communications. The absence of standardized phrases and clear, precise communication contributed to the misunderstanding between the KLM crew and the ATC.

Breakdown in Crew Resource Management:

The disaster also brought attention to the need for improved cockpit procedures and crew resource management (CRM). The hierarchical relations among crew members were scrutinized, and it was recommended that less experienced flight crew members should feel empowered to challenge their captains when they believe something to be incorrect.

In summary, the Tenerife Airport Disaster underscored the critical importance of clear and standardized radio communications in aviation. The combination of radio interference and non-standard phrasing contributed to the tragic outcome, emphasizing the need for enhanced communication protocols and crew coordination to prevent similar incidents in the future.

Poor visibility due to fog

The foggy conditions created a challenging environment for both pilots and air traffic controllers. The pilots of both planes struggled to see the runway clearly and had difficulty in accurately judging their position and the distance to other aircraft. The limited visibility also hindered the ability of air traffic controllers to adequately monitor the movement of planes on the runway. The absence of ground radar systems at the airport further exacerbated the issue, as controllers heavily relied on verbal communication, which was hampered by the poor visibility.

As the fog reduced visibility to less than 100 meters on the runway, both the KLM and Pan Am planes encountered difficulties in navigating and following instructions from the control tower. The KLM plane, attempting to take off, collided with the Pan Am plane, which was still taxiing down the runway. The poor visibility prevented the pilots of both planes from seeing each other until it was too late to avoid the collision.

The investigation following the disaster highlighted the critical role of effective communication and coordination between air traffic controllers and pilots, especially in low-visibility conditions. The disaster led to significant changes in aviation regulations, including improvements in communication systems, enhanced training for pilots and controllers, and the implementation of ground radar systems at the airport.

Runway overcrowding

The Tenerife airport disaster, which occurred on March 27, 1977, was the deadliest accident in aviation history, resulting in 583 fatalities. The incident happened at Los Rodeos Airport (now Tenerife North Airport) on the Spanish island of Tenerife when two Boeing 747 passenger jets collided on the runway. The primary cause of the accident was the decision of the KLM captain to initiate the takeoff without clearance from air traffic control. The investigation also revealed that the airport was congested with parked airplanes, blocking the only taxiway and forcing departing aircraft to taxi on the runway. This runway overcrowding, combined with dense fog, set the stage for the tragic collision.

Los Rodeos Airport was a regional airport that was not adequately equipped to accommodate the sudden influx of large aircraft rerouted from Gran Canaria Airport due to a bomb explosion. The diverted airplanes took up so much space that they had to park on the taxiway, rendering it unusable for taxiing. Consequently, departing flights had to taxi along the runway itself, a procedure known as backtaxi or backtrack. This unusual procedure contributed to the congestion and chaos on the runway.

The KLM plane, carrying 248 passengers and crew, initiated its takeoff run without receiving the necessary clearance. At the same time, the Pan Am Flight 1736, with 396 passengers and crew, was still on the same runway, awaiting takeoff clearance. The dense fog further reduced visibility for both pilots and the control tower, making it challenging to navigate the crowded runway safely.

The KLM plane collided with the right side of the Pan Am plane, resulting in a catastrophic impact and fire. All 248 people on board the KLM plane perished, along with 335 individuals on the Pan Am flight. There were only 61 survivors in the front section of the Pan Am aircraft.

The investigation into the disaster highlighted the critical importance of clear and standardized radio communications between pilots and air traffic control. It also led to a re-evaluation of cockpit procedures, emphasizing crew resource management and encouraging combined crew input during aircraft operations.

Lack of ground radar

The Tenerife Airport Disaster, which occurred on March 27, 1977, was a catastrophic event that resulted in the deaths of 583 people. The collision of two Boeing 747 aircraft, operated by KLM and Pan Am, on the runway of Los Rodeos Airport (now Tenerife North Airport) in Tenerife, highlighted several critical factors, including the lack of ground radar.

The absence of ground radar at Los Rodeos Airport was a significant contributing factor to the disaster. The airport's location, at an altitude of 610 or 633 meters, often resulted in cloudy and foggy conditions, as was the case on the day of the accident. The dense fog severely limited the visibility of both the pilots and the air traffic control tower, making it difficult for them to see each other.

The lack of ground radar meant that the air traffic controllers had to rely solely on visual observations and radio communications to track the aircraft. This created a situation where the controllers could not accurately determine the positions of the aircraft on the runway, especially in the low-visibility conditions caused by the fog.

The investigation into the disaster concluded that the primary cause of the accident was the KLM captain's decision to initiate the takeoff without proper clearance from air traffic control. The dense fog and lack of ground radar meant that the air traffic controllers were unable to see that the Pan Am aircraft was still on the runway when they gave the clearance to the KLM plane.

The lack of ground radar also hindered the ability of the controllers to monitor the aircraft's positions and speeds, which could have provided crucial information to prevent the collision. The controllers were relying on radio communications and visual observations, which were insufficient in the prevailing weather conditions.

The absence of ground radar at Los Rodeos Airport was a critical factor that contributed to the tragedy. It hindered the ability of air traffic controllers to track and manage the aircraft effectively, especially in the low-visibility conditions caused by the dense fog. This lack of technology played a significant role in the chain of events that ultimately led to the collision and the devastating loss of life.

Following the disaster, the Spanish government installed a ground radar system at Tenerife North Airport to improve situational awareness and help prevent similar incidents in the future. This addition of ground radar was a crucial step in enhancing the safety of air travel at the airport and ensuring that such a tragedy would not occur again.

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