Pontifications: A fresh look at the world’s worst aviation accident

By Scott Hamilton

Nov. 19, 2018, © Leeham News: Collision on Tenerife is a new book that dissects the worst accident in aviation history, the collision between two Boeing 747s operated by Pan American World Airways and KLM Royal Dutch Airlines.

The accident on Tenerife Island on March 27, 1977, killed 583 passengers and crew on the two airplanes. Only 61 survived, all on the Pan Am flight.

It was the worst death toll of any aviation accident.

Well-known accident

The particulars are well known to any airline aficionado. These flights, and many others, were diverted to the single-runway airport on Tenerife when a bomb went off in the airport terminal at their nearby destination. This event was the subject of several documentaries, including this one which may be seen on YouTube.

The world’s deadliest aviation accident: a collision between Pan Am and KLM Boeing 747s. Rendering via Google images.

By the time these two flights were cleared for takeoff to the original destination, after the airport reopened, fog rolled in over Tenerife. The number of airplanes diverted blocked part of the taxiway and the airport parking ramp, forcing KLM and Pan Am to taxi down the single runway.

KLM moved first. After it turned 180 degrees into position for takeoff, Pan Am was still on the runway, having missed its turnoff in the fog. The KLM pilot jumped the gun and started his take-off roll, due in part to imprecise language from the control tower, in part due to his own errors, and in part due to cross-talk of KLM, Pan Am and the controllers all using the same radio channel.

The pilots spotted each other’s airplanes through the fog too late for Pan Am to clear the runway into the grass and too late for KLM to abort the takeoff. The KLM pilot “horsed” his airplane off the runway before it was ready to fly; it collided with Pan Am and the rest is well-known history.


Author Jon Ziomek recounts these mistakes leading up to the crash. What he then does is take the reader through second-by-second, first- and second-hand accounts of the surviving passengers on the Pan Am flight: the horror of those on the right side of the airplane who saw the lights of the speeding KLM 747. The bewilderment of those on the left side who saw the Pan Am pilots was turning his airplane onto the grass. The confusion, stunned and in some cases frozen responses of passengers who survived and of some of those who didn’t.

Ziomek takes the reader through how passengers escaped and some of the difficult choices many had to make, leaving loved ones or friends and strangers behind. He explains what was going on in the control tower and how, because of the fog, they weren’t initially aware of the horrific collision.

He details precisely where the KLM 747 struck the Pan Am 747. He takes the reader with some of the passengers and their post-accident trauma.

Some of the detail makes for difficult reading. But it’s also important reading, providing those a clear understanding why listening to pre-takeoff safety announcements remains critical to survival and how psychology can freeze some people in a crisis while others spring into action.

Collision on Tenerife: The How and Why of the World’s Worst Aviation Disaster. By Jon Ziomek with special material from Caroline Hopkins. Post Hill Press, © 2018. $27.



22 Comments on “Pontifications: A fresh look at the world’s worst aviation accident

  1. So many factors came together for this tragic casualty. I’d like to think this could never happen again – two of the largest airplanes flying running into each other. Seems to me just the advances in GPS, would make this avoidable.

    • You would think.

      But then you look at the Norwegian Frigate that impales itself on a Tanker (now sunk) with pelnty of warning and propel telling them they were on a collision core

      1 degree right or left and they would have been complete clear of the tanker (or a drunken tanker captain ala the Exon Valdez)

      Don’t underestimate the power of people to do stupid things.

      An Air Canada tried to land on a taxiway at SFO that had aircraft sitting on it – you can’t tell white from blue lights?

      • 20 feet lower and they would have beaten the record with a lot fewer slices of cheese.

        • As the NTSB said :
          “lined up on parallel taxiway C, where four air carrier airplanes were awaiting takeoff clearance, including United Airlines flight 1 (UAL1), a Boeing 787; Philippine Airlines flight 115, an Airbus A340; United Airlines flight 863, another Boeing 787; and United Airlines flight 1118, a Boeing 737.. ACA759 descended below 100 ft above the ground, and the flight crew advanced the thrust levers to initiate a go-around about the time it overflew the first airplane on the taxiway. ”
          I had thought they werent as close as ‘below 100ft’

          • Hello Dukeofurl,

            Regarding:” I had thought they werent as close as ‘below 100ft’”

            It was even scarier than that. According the NTSB report, ACA 759 was at an altitude of 60 feet when it passed over PAL 115 (an Airbus 340) and missed colliding with PAL 115 by 10 to 20 feet. The quote below is from page 44 of the NTSB report. See the link after the quote for the full report.”

            “The airplane performance study for this incident showed that ACA759 continued the approach and flew over the first airplane on taxiway C (UAL1) at an altitude of 100 ft and that the flight crew initiated a go-around when ACA759 was at an altitude of 89 ft. The airplane performance study also showed that ACA759 flew over the second airplane on taxiway C (PAL115) at an altitude of 60 ft before the airplane began climbing, which resulted in only 10 to 20 ft of vertical separation between the ACA759 and PAL115 airplanes. The NTSB concludes that the flight crew-initiated, low-altitude go-around over the taxiway prevented a collision between the Air Canada airplane and one or more airplanes on the taxiway.”


          • Almost a very costly failure to follow procedure. Missed by both co-pilot and pilot is a lot harder to understand than it having been missed by only one of them. From page 41 of the NTSB report.

            “The first officer stated that, when he set up the approach in the FMC, he missed the step in the procedure to manually tune the ILS frequency, and FDR data showed that no ILS frequency
            had been entered for the approach. According to Air Canada personnel, the FMS Bridge visual approach was the only approach in the company’s Airbus A320 database that required manual
            tuning of an ILS frequency, which might have contributed to the first officer’s failure to input the frequency (as discussed below). However, the first officer’s error should have been caught by the
            captain as part of his verification of the approach setup during the approach briefing. If cockpit voice recorder (CVR) information had been available for this incident (as discussed further in
            section 2.4), the NTSB might have been better able to determine whether distraction, workload, and/or other factors contributed to the first officer’s failure to manually tune the ILS frequency
            and the captain’s failure to verify that the ILS frequency was tuned. The NTSB concludes that the first officer did not comply with Air Canada’s procedures to tune the ILS frequency for the visual approach, and the captain did not comply with company procedures to verify the ILS frequency and identifier for the approach, so the crewmembers could not take advantage of the ILS’s lateral guidance capability to help ensure proper surface alignment.”


          • The Delta crew who landed just before ACA 759 didn’t forget to tune in the ILS, and found it useful in resolving their uncertainty about the runway lighting. From page 9 of the NYSB report.

            “The DAL521 flight crewmembers were able to determine that their airplane was lined up for runway 28R after cross-checking the lateral navigation (LNAV) guidance. The DAL521 captain stated that, without lateral guidance, he could understand how the runway 28R and taxiway C surfaces could have been confused because the lights observed on the taxiway were in a straight line and could have been perceived as a centerline. The DAL521 crewmembers confirmed that their airplane was lined up correctly when they visually acquired the painted “28R” marking on the paved surface of the runway; they estimated that their airplane was at an altitude of 300 ft at that time.”


          • What was the reason the CVR wasn’t available?
            Surely they knew there was a major incident.
            The current requirement is to only record the previous 2 hrs, they want it to be 25 hrs but only on new aircraft after 2024! Clearly a major technical challenge ?

          • Hello Dukeofurl,

            Regarding: “What was the reason the CVR wasn’t available?
            Surely they knew there was a major incident.”

            See the excerpt below from pages 58 and 59 of the NTSB report.

            “According to the dispatcher who received the initial notification about the event, the captain reported that the airplane was lined up with the wrong runway and that a go-around was performed. The dispatcher also stated that the captain’s report sounded “innocuous” given the amount of time (16 hours) that had elapsed since the event. However, Air Canada senior personnel first learned about the severity of the event—the proximity of the incident airplane to the airplanes on the taxiway—when the TSB sent an e-mail about 2200 EDT on July 9 that advised company personnel about the incident circumstances. The Air Canada A320 assistant chief pilot stated
            that, during a meeting on July 10, the flight crewmembers were told that ACA759 had overflown airplanes on a taxiway and that the crewmembers’ responses were “shock” and “surprise.” (The
            NTSB could not determine if the flight crew was aware, before this meeting, that ACA759 had flown over airplanes on taxiway C.)

            Air Canada’s director of corporate safety, investigation, and research stated that the incident airplane had flown about 40 hours before Air Canada senior officials became aware of the
            severity of the incident and realized that data from the airplane needed to be retrieved. However, by that point, the CVR information from the incident flight had been overwritten; the CVR installed in the incident airplane was designed to record 2 hours of operational data.”

            I find some of the above hard to square with this excerpt from page 31.

            “In addition, the SFO acting air traffic manager reported that he and other ATCT personnel interviewed the incident captain at 1140 on July 8. During that conversation (which was not
            recorded), the acting air traffic manager notified the captain of the possible pilot deviation. According to FAA Order JO 7210.632, Air Traffic Organization Occurrence Reporting, this notification is provided when an “employee providing air traffic services determines that pilot actions affected the safety of operations.” The order also indicated that this notification was to be
            part of the air traffic mandatory occurrence report and that the flight crew should be notified “as soon as operationally practical.”

          • More on the subject of: ” What was the reason the CVR wasn’t available?
            Surely they knew there was a major incident.”

            From page 30 of the NTSB report.

            “The captain stated that he also spoke with the duty pilot to report that he had aligned the airplane with a taxiway and performed a go-around. The captain indicated that the duty pilot asked him whether the localizer was tuned, and the captain replied that it was not tuned for the first approach but was tuned for the second approach. According to Air Canada’s vice president of safety, after the flight crew notified the duty pilot of the incident, the senior director of line operations determined that the flight crew would be allowed to operate the flight from SFO to YYZ (using a different airplane than the incident airplane) and then “would be held out of service” after arriving at YYZ later that day.”

            From pages 74 and 75 of the report.

            “In this event a commercial aircraft filled with passengers came within feet of striking another aircraft and causing a collision with several others on the ground. Over 1000 people were at imminent risk of serious injury or death. The commercial operator had policies in place that required the reporting of serious incidents and that would have removed the flight crew from service immediately and until they could be evaluated for flight readiness. However, the subjective observations of the crew as they flew over the aircraft on the ground and executed a go-around did not prompt them to report anything to their operational control until the next day. Moreover, they reportedly did not perceive the gravity of the situation, stating to NTSB investigator they did not descend below 400ft prior to initiating a go-around. According to the crew, they did not realize just how near they were to striking another aircraft.”

            “There was only one controller in the tower that night and his work load was significant. Yet, while he was expected to continue his solo operation, he also had unique knowledge of the events that had just occurred. It was the controller who called for the go-around, knew the Air Canada flight almost landed on an active taxiway, reported the Air Canada crew was shaken, and stated that he himself was other than calm after the event. When a pilot on the ground contacted the controller to report the Air Canada flight had gone right over him, the controller replied that he had seen it happen. Yet, the controller did not report the event in the system until the end of his shift. When he did so, it was only as a go-around and he chose not to mark the event as significant when prompted by his reporting software.”

            “I am left concerned that post-incident forensic analysis of a cockpit voice recorder, while vital, cannot replace immediate, safety-focused interventions designed to take crews involved in near miss situations out of service until they can be assessed as safe to continue. Whether it is industry, the FAA, or airports that stand up a more effective “if you see something, say something” style system regarding dangerous operational behavior, it is clear to me that the need exists.

            Vice Chairman Landsberg and Member Dinh-Zarr joined this statement.”

            Hindsight is always 20/20?

        • Any light that is used at an airport or navigational purposes, is the right color.

          LED general characteristics do not apply. If they need to, for that purpose, they are “adjusted” to do so.

          This applies to any light type. The regs are specific.

          • I was thinking that the pilots might have become accustomed to white lights with a blue tint in their everyday lives.

  2. A nautical equivalent a couple of decades earlier might be the collision at sea in the fog off NYC harbor of the Italian ocean liner Andrea Doria with the Swedish cargo freighter Stockholm, resulting in the sinking of the passenger ship with many lives lost. One would hope that, for both modes of travel, technology has now rendered such massive disasters obsolete. But, has it really?

    • AIS has made quite a lot of difference at sea, but just created more ways in which a lazy crew doesn’t have to keep a proper lookout. That, plus autopilots, makes for an early shift for George and an early clock-off for the human crew. Which is great until someone else sinks their car transporter in the sealane.

      Still, if one has got an AIS transponder on your day cruiser, it’s going to make bleeping sounds on the deck of that supertanker at just the same volume as if one were at the wheel of an aircraft carrier. An alarm signal sounding on their bridge will be a lot louder than one’s own tin whistle a mile away, no matter how hard one blows it.

    • In this same vein, these huge 3000 to 5000 passenger liners are not as seaworthy as the SS United States or the SS France or the Queen Elizabeth. Those steamers had huge reliable turbines that were almost flawless. Just look at these almost 20 story floating hotels. Anyone can see they are not seaworthy. The rational is that they aren’t used as much to cross an open ocean. But they’ve had plenty of weather in the Gulf, the Med, etc.,… to deal with.

  3. Yes the worst disaster in aviation history. But there is a differnce between making decisions in haste and making careful decisions. The biggest cover up in aviation history is the DC-10. Lets hope we never go back there

      • Thank you Phillip. It truly was a Poster Child of how Aviation should not be handled.

        Of course we have all these other issues going on that are hanging out. So we issue an ETOPs on an iffy engine.

        Trent 10 proceeded this engine, so…………


        As noted Runway excursions continue and sooner or latter someone dies.

        The original 737 Ruder issue was also an ugly one.

        As was the 767 Lauda Air.

        TWA 800 clearly shot down by a missile (had to slip that one in)

        Or perhaps the nice wiring job on the MD-11?

        Clearly it is a case of Aircraft Roulette.

        But then there is leaving the house in the car (granted we have 7 airbags in the Passat. ) Hopefully none made by Takata.

        • I do like your posts on Rolls Royce.

          Major OEMs self regulate. In other words the regulators issue a certificate of self regulation.

          With regard to the Trent 1000, Rolls Royce owned up as soon as they knew the issue. Specfically they owned up there was a harmonic between the fan and the IPC

          With regard to the Trent 7000, they have made it very clear that the harmonic could be present because the interaction between the fan and the IPC hasn’t changed.

          They have developed a fix to remove the harmonic. They will roll out the fix to the Trent 1000 and then the Trent TEN/Trent 7000.

          In other words get rid of the issue once and for all. It was just bad luck that the harmonic existed for it cannot be predicted. Fortunately, Rolls Royce now have the technology to determine the existence of harmonics with shaft speed greater than 10,000 rpm. That will keep them in good stead.

          The thesis of my post is tell the truth. Rolls Royce will recover from what is a setback because the airlines will admire how they are dealing with the setback. The A330neo and the A350 are performing their socks off

Leave a Reply

Your email address will not be published. Required fields are marked *