The Tenerife Airport Disaster: How Fueling the KLM 747 Impacted the Tragic Collision

The Tenerife Airport Disaster, occurring on March 27, 1977, was a significant air accident involving two Boeing 747 aircraft, a KLM plane and a Pan Am plane, colliding on the runway at Los Rodeos Airport, now known as Tenerife North Airport, in the Canary Islands. The disaster was primarily attributed to miscommunication and misunderstandings between flight crews and air traffic control. However, the fueling of the KLM aircraft is often debated in discussions surrounding the accident.

Did the KLM 747 Require a Full Fuel Load for Takeoff?

The question often arises: would the KLM 747 have taken off without hitting the Pan Am plane if it was not fully refueled? It is essential to examine the impact of a lighter fuel load on the aircraft's takeoff. While a lower fuel load might have reduced the takeoff weight, leading to a shorter takeoff distance and better performance, this is not the primary issue that caused the disaster. The core issue was a combination of human factors, including miscommunication, poor visibility, and pressure to depart.

Human Factors and Miscommunication

The primary cause of the Tenerife Airport Disaster was miscommunication between the flight crews and air traffic control. The KLM flight crew misunderstood air traffic control instructions and believed they had clearance to take off when they did not. This misunderstanding set the stage for the tragic collision. Additionally, poor visibility due to dense fog at the airport made it difficult for the pilots to see the Pan Am aircraft on the runway.

Visibility and Conditions

The fog at the airport significantly reduced visibility, making it challenging for the pilots to identify the Pan Am aircraft on the runway. This poor visibility was a critical factor in the accident, as the KLM crew may not have seen the Pan Am aircraft until it was too late. Even with a lighter fuel load and therefore less takeoff weight, the dense fog would still have prevented the KLM crew from seeing the Pan Am aircraft, thus contributing to the collision.

Pressure to Depart

The KLM crew was under pressure to depart due to a previous lengthy delay. This pressure may have influenced their decision-making, leading them to disregard safety protocols and take off without proper clearance. The situation was exacerbated by the dense fog, which made the runway conditions extremely hazardous. Regardless of the aircraft's fuel load, the takeoff roll would have faced the same challenges due to visibility and safety concerns.

The AOT Technique and Performance Characteristics

The aircraft used a technique called "Assumed Outside Temperature" (AOT) or "derated takeoff," which is standard in large airliners and commonly used in smaller aircraft when possible. This technique involves operating the engines at a lower power output than their maximum rated power. The exact power to use is calculated to ensure the aircraft can safely take off using a maximum portion of the runway, even under adverse conditions. This technique ensures that the aircraft can either take off safely or come to a stop if an engine fails during takeoff.

The AOT technique eliminates the need for precise weight considerations, as the aircraft's performance characteristics are consistent regardless of its weight. By using a derated takeoff, the aircraft will reach a similar percentage of flying speed at a specific point in the takeoff roll, regardless of the fuel load. A lighter aircraft might have more authority for engine response but only over a longer period. In this critical situation, the KLM 747 clearly had limited time to react, highlighting the limitations of relying solely on fuel load to avoid the disaster.

While a lighter fuel load might have yielded different performance characteristics, it is unlikely to have altered the critical circumstances that led to the collision. The Tenerife Airport Disaster was fundamentally caused by miscommunication, poor visibility, and pressure to depart, not by the specific amount of fuel in the KLM 747.

The Tenerife Airport Disaster serves as a sobering reminder of the importance of clear communication, situational awareness, and adherence to safety protocols. While the fueling of the KLM 747 may have influenced its performance slightly, it is the human factors and environmental conditions that played the most crucial role in this tragic event.