From the Logbook: The 1977 Tenerife Airport Disaster Revisited

A Research Project About Aviation Safety

© Jim Trusty 2010

The Tenerife Airport disaster that took place on March 27, 1977, involved the collision of two 747 passenger aircraft on the runway at Los Rodeos Airport (now known as Tenerife North Airport) on the Spanish island of Tenerife, one of the Canary Islands. With 583 total fatalities and 61 total survivors it remains the deadliest accident in the history of aviation.

Whenever I hear of an accident or incident that can be accredited to pilot error, runway incursion, ATC error, technical limitations, or a security breach, I am reminded of the Tenerife disaster that included everything mentioned above and more. I always wonder how all these mistakes came together in a flight and ground plan without someone recognizing before it was too late that they were about to be in serious trouble. Sadly, it was and is possible.

Everything that took place as a part of this disaster did so within a four hour window of events, and everything that you could put at the scene of an accident was present far in advance. If you were casting a horror film, you could not have found a better script.

Los Rodeos became an unscheduled stop for both planes that day in 1977, a Pan Am flight from Los Angeles and a KLM flight from Amsterdam. Both aircraft were bound for Gran Canaria International Airport, which was also known as Las Palmas Airport, and both aircraft had top-notch, well-trained crews on board. Pan Am carried 380 passengers and 15 crew members; KLM carried 235 passengers and a crew of 14.

A terrorist bomb exploded in the terminal at Gran Canaria. The civil aviation authority immediately closed the airport and diverted all flights (including at least 5 large aircraft including the two 747s) to the smaller Los Rodeos Airport. Los Rodeos was a regional airport consisting of one runway, one major taxiway and several small taxiways. While waiting for the main airport at Gran Canaria to reopen, the planes took up so much space on the main taxiway that it could no longer be used for taxiing. The only way left for an aircraft to depart was by back taxiing.

As soon as the terrorist threat was contained at Gran Canaria the runway was reopened. The Pan Am flight was ready for departure but the KLM flight decided to take on a full load of fuel at Los Rodeos, supposedly to save time, and in doing so blocked the way to the active runway. Pan Am became stuck behind the KLM flight and this added to the terrible list of “anything that can go wrong, probably will.”
During the 35 minutes it took the KLM plane to refuel the weather deteriorated. The tower was operating in the blind due to heavy fog and lost visibility with both aircraft. A breakdown in communications between the tower and both airplanes ensued and neither crew was able to see the other plane on the runway because of limited cockpit visibility. Communication misunderstandings became even worse. KLM was given instructions by the tower to back taxi. Soon after Pan Am was also instructed to back taxi, follow the KLM flight down the same runway and exit the runway by the “third exit” on their left. The Pan Am crew became unsure of their position on the runway. During taxiing the weather further deteriorated and low flying clouds now limited the visual range to about 1,000 feet. The legal or stipulated threshold for takeoff was 2,000 feet visibility as noted in one of the documentaries and relayed by a surviving Pan Am pilot in a later interview.

The KLM Captain misunderstood the controller and thought he was cleared for takeoff. KLM thought the Pan Am flight had cleared the runway and mistakenly took off without further clearance from the Tower. At the very last minute, the Pan Am 747 spotted the KLM 747’s landing lights just as it approached the C-4 exit. The Pan Am went to full power and made a slight left turn in hopes of avoiding a collision. As the KLM tried to climb over the oncoming flight he scraped the tail for about 70 feet and then made contact with the top of the Pan Am craft at about 140 knots. The KLM was briefly airborne but the contact had damaged everything it needed for flight causing it to stall and crash about 500 feet from where the collision took place. As the jet was fully fueled, it immediately became a deadly inferno. Because of the heavy fog, rescue crews were not aware that the Pan Am aircraft was involved in the crash for over 20 minutes.

Over 70 crash investigators were involved from Spain, the US, the Netherlands, and the two airline companies, and 50 reports were written along with magazine articles, TV programs and movies that were made exploring this crash from start to finish. It is probably the most complete investigation ever made of an airplane mishap.

The conclusions reached were that the fundamental causes of the accident were many. They included the KLM Captain’s failure to confirm tower instructions and taking off without a proper clearance and the flight engineer’s failure to challenge the captain. Blame was shared by the captain, flight engineer and the first officer for not getting clearer instructions from the tower. The extra fuel they took on added 35 minutes to their takeoff along with forty tons of weight and increased the size of the fire that killed everyone on board. The sudden fog gave them limited visibility. The control tower and the crews of both planes were unable to see one another. Overlapping radio transmissions occurred with the end result that neither message could be understood. The non-standard phrases used by the KLM co-pilot and the Tower as well as Pan Am continuing to exit C-4 instead of exiting at C-3 as directed and the airport being forced to accommodate a greater number of large aircraft than could safely be handled also contributed to the accident. Although the Dutch authorities were initially reluctant to blame the KLM captain and crew, they paid the victims and their families compensation ranging between $58,000 and $600,000.

As a consequence of the accident, many changes were made to airline regulations and to the aircraft involved. Aviation authorities introduced requirements for the use of English and standard phrases. A lot of emphasis was placed on using ICAO language like “line up and wait” instead of “position and hold” in hopes that it would be a lot less confusing and that the international pilots would be more comfortable with this method of transmitting information. More emphasis was placed on using Crew Resource Management, a mutual agreement method, due to the KLM co-pilot not challenging the Captain’s decision to takeoff.

This accident is probably the most widely investigated aviation occurrence we have ever had. As you read this story, I hope you will be interested to look up more information to see exactly what transpired. You may discover something else that might have been done differently to avoid this tragic loss of life and equipment. Something surely could have been done before it was too late that would have avoided taking the lives of 583 passengers and crew members and the destruction of two great aircraft that fateful day.

I appreciate your taking an interest in aviation safety. It is the deciding factor in what happens to our jobs and the industry itself. I look forward to hearing your views about this particular accident and how it was handled by the investigators. Your interest may add further insight into all that went wrong that day.

Written permission required to reprint this copyrighted article (2010).

JAMES E. (Jim) TRUSTY, ATP~IGI~CFI~AGI was named the FAA/Aviation Industry National Flight Instructor of the Year for 1997, and the first ever FAA Southern Region Aviation Safety Counselor of the Year in 1995 and then again in 2005. He still works full-time as a Corporate 135 Pilot~ “Gold Seal” Flight & Ground Instructor~ FAA Safety Team Program Lead Representative~ National Aviation Magazine Writer. You have been enjoying his work since 1973 in publications worldwide. If you have comments, questions, complaints, or compliments, please e-mail them directly to him, and he will certainly respond. Take a moment and visit his new website listed below. I think you’ll find it useful. Thanks.

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