Lessons Learned

Technical Related Lesson

Clearances to move about an airport, especially clearances to take off or land, should be clear and unambiguous, and compliance should be exact. (Threat Category: Midair/Ground Incursions)

  • In this accident, traffic at the airport was unusually congested, requiring the use of all available taxiways, and even the runway to expedite movement of traffic for takeoff. Rapidly changing and deteriorating weather further complicated traffic movement on the ground. Both the KLM and Pan Am flights were back taxiing on the runway at the same time in order to accommodate the desired imminent departure of both flights. Deteriorating visibility created some confusion on the part of the Pan Am crew as to the proper taxiway at which to exit the runway, and KLM had accomplished a 180-degree turn at the end of the runway and was waiting in position for takeoff clearance. Upon receiving a departure clearance, the KLM flight misunderstood this as a takeoff clearance and began their takeoff roll with Pan Am still on the runway. Had the KLM crew questioned the clearance, or queried the control tower as to the location of the Pan Am flight, the accident may have been avoided.

Flight crew communications regarding airplane safety readiness should be open and effective. Each crew member must clearly give and receive communication in such a way that the flight safety decisions represent the best product of this open, two-way communication. (Threat Category: Crew Resource Management)

  • In this accident, the flight engineer apparently heard the Pan Am crew state that they would report to the tower when they were clear of the runway, and were therefore still on the runway. The flight engineer then asked the KLM captain, "Is he not clear, then?" The KLM captain replied, "What do you say?" and the flight engineer reiterated, "Is he not clear, that Pan American?" The captain responded with an emphatic "Oh, yes" and continued the takeoff. The impact occurred 13 seconds later. It was believed by the investigators that the other crew members did not further question the captain's actions due to his senior position within the company. When the flight engineer perceived a miscommunication with the clearance, his lack of insistence that the captain listen to him resulted in the captain proceeding with the takeoff, and the resulting accident.

Common Theme Related Lessons

Deviations from operations or procedures that are considered normal, or routine, increase the risks for human errors of all kinds. When it is necessary to deviate from normal operations, extra vigilance and strict adherence to proper procedures should be emphasized. (Common Theme: Human Error)

  • A bombing at the Las Palmas airport, the intended destination of both the KLM and Pan Am flights, as well as many others, caused a diversion to and an unusual situation at the Tenerife airport. Everyone involved, from each flight to the air traffic controllers, were forced to compensate for the unusual circumstances. In a cascading series of deviations from normal, routine events, confusion in the cockpits of both the KLM and Pan Am flights and in the control tower led to a series of errors that resulted in the accident.

Regulatory standards should be sufficiently flexible to allow deviation in special circumstances, without compromising safety. Application of an appropriate alternative can result in the level of safety intended by the regulation. (Common Theme: Unintended Effects)

  • A revised Dutch regulation, imposing new limitations on crew duty time, was discussed in the accident report and was concluded to have had an influence on the decision-making of the KLM captain. Previous duty time regulations allowed a captain some flexibility in extending the crew's duty time. The new law, enacted in December 1976, was inflexible, and compliance was difficult. Furthermore, if duty times were exceeded, a captain could be liable for criminal prosecution. The law had originally been intended to prevent negligence among flight crews in adhering to duty time requirements. It was originally viewed as a means to improved safety by assuring that flight crews were adequately rested and remained alert for the duration of a flight. The unintended effect, in the case of the Tenerife accident, was exactly the opposite. According to the accident report, the captain became preoccupied with duty time limitations and was approaching a time deadline, after which the flight would have to be cancelled. The investigation concluded that his preoccupation with not exceeding the deadline may have influenced his decision making, and led to a series of unsafe actions that resulted in the accident.

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