The Tenerife Airport Disaster occurred on March 27, 1977, profoundly impacting the aviation industry. At Los Rodeos Airport in Tenerife, a KLM Boeing 747 commenced takeoff without proper clearance from air traffic control, leading to a catastrophic collision with a Pan Am 747 that was awaiting clearance on the runway.
This devastating event resulted in the loss of 583 lives. There were no survivors among the occupants of the KLM aircraft, and only 61 individuals managed to escape from the wreckage of the Pan Am plane. Among those who survived were 61 individuals, including several flight attendants. In this account, we delve into their remarkable story.
How Did the Tenerife Airport Disaster Take Place?
The Tenerife airport disaster occurred on March 27, 1977, when two Boeing 747 passenger jets collided on the runway of Los Rodeos Airport, now known as Tenerife North Airport, located on the Spanish island of Tenerife.
The collision occurred when KLM Flight 4805 initiated its takeoff while Pan Am Flight 1736 was still on the runway. This tragic incident resulted in the loss of all occupants on board KLM 4805 and most of those on Pan Am 1736, with only 61 survivors in the front section of the aircraft.
With a total of 583 fatalities, this remains the deadliest accident in aviation history.
The presence of a bomb, set off by the Canary Islands Independence Movement at Gran Canaria Airport, had caused numerous flights to be diverted to Los Rodeos, including the two planes involved in the accident.
This influx of diverted aircraft led to congestion at the airport, with parked planes obstructing the only taxiway and forcing departing aircraft to taxi on the runway instead. Additionally, patches of thick fog were present, reducing visibility for pilots and the control tower.
Following the incident, a thorough investigation conducted by Spanish authorities determined that the main cause of the accident was the KLM captain’s decision to take off, mistakenly believing that they had received clearance from air traffic control (ATC).
Dutch investigators emphasized a miscommunication between the KLM crew and ATC over radio communications. Still, ultimately KLM accepted responsibility for the accident, agreeing to provide financial compensation to the families of all the victims.
This disaster impacted the aviation industry, particularly in underscoring the crucial importance of using standardized phraseology in radio communications. Cockpit procedures were also reviewed, leading to the establishment of crew resource management as an essential part of airline pilot training.
The notion of the captain as infallible was challenged, promoting a culture of collective decision-making among the crew during aircraft operations.
The Prelude to the Tenerife Airport Disaster
Both KLM Flight 4805 and Pan Am Flight 1736 were originally scheduled to land at Gran Canaria Airport, which serves Las Palmas on the neighboring island of Gran Canaria.
However, due to unforeseen circumstances, both flights made an unscheduled stop at Tenerife, which is part of the Canary Islands, an autonomous community of Spain located in the Atlantic Ocean off the southwest coast of Morocco.
KLM Flight 4805 was a charter flight operated by Holland International Travel Group. It originated from Amsterdam Airport Schiphol in the Netherlands. The cockpit crew consisted of Captain Jacob Veldhuyzen van Zanten (50 years old), First Officer Klaas Meurs (42 years old), and Flight Engineer Willem Schreuder (48 years old).
At the time of the accident, Captain van Zanten held the position of KLM’s chief flight instructor and had accumulated 11,700 flight hours, including 1,545 hours on the Boeing 747. First Officer Meurs had 9,200 flight hours, with 95 hours on the 747, while Flight Engineer Schreuder had 17,031 flight hours, including 543 hours on the 747.
The aircraft involved was a Boeing 747-206B with registration PH-BUF and named Rijn (Rhine). It carried a total of 14 crew members and 235 passengers, including 52 children. Most of the passengers were Dutch, and four Germans, two Austrians, and two Americans were on board.
Upon landing at Tenerife, the passengers were taken to the airport terminal. One passenger, Robina van Lanschot, who resided on the island with her boyfriend, chose not to re-board the 747, leaving a total of 234 passengers on board.
Pan Am Flight 1736 originated from Los Angeles International Airport with a layover at John F. Kennedy International Airport in New York (JFK). The aircraft was a Boeing 747-121 with registration N736PA and named Clipper Victor.
It was the first 747 delivered to an airline. Of the 380 passengers, the majority were retirees, and two children were among them. Fourteen passengers had boarded the aircraft in New York, where the crew was also changed. With the exception of five passengers, all were Americans, while the non-American passengers were Canadian nationals.
The new crew consisted of Captain Victor Grubbs (56 years old), First Officer Robert Bragg (39 years old), Flight Engineer George Warns (46 years old), and 13 flight attendants. Captain Grubbs had accumulated 21,043 flight hours, including 564 hours on the 747.
First Officer Bragg had 10,800 flight hours, with 2,796 hours on the 747, while Flight Engineer Warns had 15,210 flight hours, including 559 hours on the 747.
The Day of the Horrible Tenerife Airport Disaster
Following a routine flight, both KLM Flight 4805 and Pan Am Flight 1736 encountered unforeseen circumstances as they approached the Canary Islands. At 13:15, a bomb placed by the Canary Islands Independence Movement detonated at Gran Canaria Airport’s terminal, causing injuries to eight individuals.
The airport authorities received a phone call warning of the bomb and subsequent claims of another bomb at the airport. As a result, the airport was temporarily closed, diverting all incoming flights bound for Gran Canaria, including the two aircraft involved in the tragic accident.
The Pan Am Flight 1736 crew expressed their preference to circle in a holding pattern until they received landing clearance (as they had sufficient fuel to remain in the air for two more hours). However, they were instructed to divert to Tenerife instead.
Los Rodeos Airport, where the planes were diverted, was a regional airport that was ill-prepared to handle the sudden influx of diverted traffic from Gran Canaria. This included five large airliners. The airport only had one runway and one major parallel taxiway, with four short connecting taxiways.
Due to the crowded conditions, the diverted airplanes were forced to park on the lengthy taxiway, rendering them unusable for taxing purposes. As a result, departing aircraft had to taxi along the runway to position themselves for takeoff, a procedure known as back taxi or backtrack.
Once the bomb threat at Gran Canaria Airport was contained, the authorities decided to reopen the airport. The Pan Am aircraft was ready for departure from Tenerife; however, the KLM aircraft and a refueling vehicle obstructed access to the runway.
The KLM captain had chosen to fully refuel at Los Rodeos instead of Las Palmas, presumably to save time. The Pan Am plane could not maneuver around the refueling KLM aircraft to reach the runway for takeoff due to the dangerously close proximity between the two planes, with a clearance of only 3.7 meters (12 ft).
The refueling process took approximately 35 minutes, and the passengers were brought back to the aircraft. The search for a Dutch family of four, who had not returned to the waiting KLM plane, further delayed the flight.
Robina van Lanschot, a tour guide, had decided not to reboard the flight to Las Palmas since she lived in Tenerife and considered it impractical to fly to Gran Canaria only to return the next day.
As a result, she was not on the KLM plane when the accident occurred, making her the sole survivor among those who had flown from Amsterdam to Tenerife on Flight 4805.
How Did the Tenerife Air Disaster Take Place?
The air traffic control tower instructed the KLM aircraft to taxi along the entire runway length and then make a 180° turn to position itself for takeoff. As the KLM plane was taxiing on the runway, the flight crew was asked by the controller to report when they were ready to copy the air traffic control clearance.
However, as they went through the checklist, the crew postponed copying the clearance until the aircraft was in the takeoff position.
Shortly after, the Pan Am aircraft received instructions to follow the KLM plane on the same runway, exit by taking the third left turn, and then use the parallel taxiway. The Pan Am cockpit was initially confused about whether they were instructed to take the first or third exit.
The crew sought clarification, and the controller emphatically responded, stating, “The third one, sir; one, two, three; third, third one.” The crew began taxiing and relied on an airport diagram to identify the unmarked taxiways as they reached them.
The crew successfully identified the first two taxiways (C-1 and C-2), but their conversation in the cockpit indicated that they had not spotted the third taxiway (C-3) as instructed. The lack of markings or signs and poor visibility conditions made it challenging for the Pan Am crew to determine their position on the runway until the collision occurred near the intersection with the fourth taxiway (C-4).
The third taxiway’s angle would have required the Pan Am aircraft to make a 148° turn, leading them back towards the still-congested main apron. At the end of C-3, another 148° turn would be necessary to continue taxiing towards the start of the runway, resembling a mirrored letter “Z.” Taxiway C-4 would have involved two 35° turns.
After the accident, a study conducted by the Air Line Pilots Association (ALPA) concluded that executing the second 148° turn at the end of taxiway C-3 would have been “practically impossible.” The official report from Spanish authorities explained that the controller instructed the Pan Am aircraft to use the third taxiway because it was the earliest available exit that would lead them to the unobstructed section of the parallel taxiway.
Los Rodeos airport’s location at an elevation of 633 meters (2,077 ft) results in different weather conditions than many other airports. Clouds that are 600 m (2,000 ft) above ground level at the nearby coast reach ground level at Los Rodeos.
Drifting clouds of varying density cause unpredictable changes in visibility, ranging from clear to below the legally required minimum in a matter of seconds. The collision occurred within a high-density cloud.
The Pan Am crew encountered poor visibility that rapidly deteriorated as soon as they entered the runway. According to the ALPA report, visibility was approximately 500 m (1,600 ft) when the Pan Am aircraft taxied to the runway. Shortly after turning onto the runway, visibility dropped to less than 100 m (330 ft).
Meanwhile, the KLM aircraft still had good visibility, but clouds were moving toward them along the runway. In relatively clear weather, the KLM plane completed its 180-degree turn and aligned itself on Runway 30.
The next cloud was located 900 m (3,000 ft) down the runway and moving towards the aircraft at a speed of approximately 12 knots (14 mph; 22 km/h).
The Main Reason Behind the Tenerife Air Disaster
The communication between the cockpit and the air traffic control (ATC) tower played a significant role in the Tenerife Airport Disaster. The miscommunication and the breakdown of chaos also had a significant contribution. Here’s a breakdown of the key communications:
- KLM Captain’s Advance: The KLM captain advanced the throttles and started moving the aircraft forward without receiving ATC clearance. First Officer Meurs reminded him that they had not yet received clearance, to which the captain responded that he knew and instructed Meurs to ask for clearance.
- Requesting Clearance: First Officer Meurs radioed the tower, stating that they were “ready for takeoff” and “waiting for our ATC clearance.” The tower then provided instructions for the route after takeoff but did not explicitly grant takeoff clearance.
- Readback and Interruption: Meurs returned the flight clearance to the controller, concluding with the statement, “We are now at takeoff.” However, Captain van Zanten interrupted the readback, stating, “We’re going.”
- Tower Response: The controller, unable to see the runway due to fog, initially responded with “OK,” a nonstandard term. This further reinforced the KLM captain’s misinterpretation that they had takeoff clearance. The controller then quickly added, “Stand by for takeoff; I will call you,” indicating that he did not intend for the instruction to be interpreted as takeoff clearance.
- Simultaneous Radio Interference: A radio transmission from the Pan Am crew interfered with the KLM cockpit’s communication, creating a three-second-long shrill sound. This interference blocked the crucial portion of the tower’s response, which could have alerted the KLM crew to the situation and allowed them to abort the takeoff.
- Miscommunication about Runway Clearance: The Pan Am crew, upon hearing the KLM aircraft initiating takeoff, radioed the tower, stating, “OK, will report when we’re clear.” The KLM flight engineer expressed concern about the Pan Am not being clear of the runway, but Captain van Zanten assured him that the Pan Am was clear.
- Collision: The Pan Am crew spotted the KLM aircraft’s landing lights through the fog as they approached exit C-4. Captain Grubbs exclaimed, “There he is!” The KLM aircraft was already moving too fast to stop when its pilots saw the Pan Am.
The KLM crew attempted to lift off prematurely, causing a tail strike and a collision with the Pan Am. The impact severely damaged both aircraft, resulting in a catastrophic accident.
It’s important to note that miscommunications, misunderstandings, and poor visibility conditions contributed to the collision, leading to the tragic outcome.
The Victims of the Tenerife Air Crash
The collision resulted in the complete destruction of both aircraft involved. All 248 passengers and crew onboard tragically lost their lives on the KLM plane. Similarly, 335 passengers and crew members perished on the Pan Am plane, primarily due to the fire and explosions caused by the spilled and ignited fuel upon impact.
However, 61 passengers and crew aboard the Pan Am aircraft survived the incident. Initially, there were 70 survivors, but unfortunately, nine of them succumbed to their injuries later. Remarkably, the captain, first officer, and flight engineer were among the survivors.
Many of the Pan Am survivors safely exited the aircraft by walking out onto the intact left wing through openings in the fuselage structure, away from the site of the collision.
Following the collision, the engines of the Pan Am aircraft continued to run for a few minutes, despite the first officer’s intent to shut them down. The upper section of the cockpit, which housed the engine switches, had been destroyed in the collision, and all control lines were severed, rendering the flight crew unable to control the aircraft’s systems.
The survivors awaited rescue, but it did not arrive promptly. Initially, the firefighters, unaware that two aircraft were involved, focused their efforts on the KLM wreckage located several hundred meters away in the dense fog and smoke.
Eventually, most of the survivors on the wing chose to descend to the ground below.
The Results of the Tenerife Air Crash
The Tenerife disaster had a profound impact on aviation safety protocols and left a lasting legacy in terms of reducing risk in air travel. One significant area of improvement was the enhancement of communication between cockpit staff and air traffic control.
Lessons learned from the accident emphasized the importance of clear and unambiguous instructions and the need for effective readbacks and confirmation of critical information. This led to the implementation of more efficient communication protocols, ensuring that both pilots and air traffic controllers have a shared understanding of instructions and clearances.
Another area that saw improvements was the development of aircraft warning systems. The accident highlighted the need for systems that could effectively alert pilots to potential hazards and errors, including situations where pilot error might play a role.
As a result, advancements were made in warning systems, providing pilots with better information and allowing them to make informed decisions to mitigate risks.
Furthermore, the disaster prompted changes in how airliners manage take-off and landing slots. Restrictions were imposed on double landings, where one aircraft would land while another was still on the runway, to reduce the potential for runway incursions and collisions.
General visibility standards also became stricter over time, ensuring that aircraft operations are conducted under safer visual conditions.
The legacy of the Tenerife disaster is evident in the improved safety measures and practices that have been implemented in the aviation industry. The changes in aircraft warning systems, communication protocols, and operational procedures have collectively contributed to a safer flying environment.
Passengers today benefit from enhanced situational awareness, quicker response times to potential risks, and the integration of advanced technologies to prevent and mitigate accidents. As a result, the overall risk for passengers when traveling by air has been significantly reduced.
Next, read about the Death Row All Stars, the Baseball Team Forced to Play for their Life. Then, about the Terrifying Story of the Titan Submersible Disaster.
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