Human Factors: Tenerife Crash 1977 Part 1 of 8
Aviation’s Worst Disaster Part 1 of 8 583 Dead at Tenerife On March 27th 1977, two mechanically sound Boeing 747 aircraft collided on a runway in the Canary Islands.
On March 27th 1977, two mechanically sound Boeing 747 aircraft collided on a runway in the Canary Islands, 100 Kilometres off the coast of Morocco, killing 583 travellers. Like with most airline tragedies there existed a chain of events that seemed like stepping-stones leading to catastrophe. Some authors point out that the tragedy was comprised of all the classic contributing factors for an aircraft disaster: there was an act of terrorism, a technical problem (Communication), a weather issue, and of course human factors. It is important for us to recognize that terrorism, technical problems, and weather were not the cause of the tragedy. It was the decisions that the humans made, in response to the events, that cause the deaths of so many.
Tenerife is a prime example of how human leverage (technology) has outpaced the awareness of our choices and our working grasp of our exposure to consequence. I present the idea that there are eight pairs of choices that humans can make. Each decision is a selection between a limiting (Shadow based) choice or an expansive (value based) choice. I postulate that the runway disaster at Tenerife is a classic example of a series of limiting choices made by the individuals that funneled everyone involved into chaos and destruction.
It is my observation, that if we become aware of these choices and understand their power, we can enter into the next level of understanding human factors as they relate to managing risk in high consequence situations. When we understand that alternate decisions can be made that provide more options, we then can disrupt a trajectory of events to mitigate horrific outcomes in whatever high consequence situation we might be involved with. Sensitivity to and choosing expansive outcomes as opposed to choosing limiting outcomes, is the key.
Chain of choices. Tenerife choices are clearly in shadow and resulted in total chaos.
Tenerife Narrative
Two Boeing 747 aircraft were en route to Gran Canaria Island carrying passengers on vacation to enjoy the warmth and beauty of the Canary Islands. Pan Am flight 1736 originated in Los Angeles, routed through New York City, carried 396 passengers, comprised mostly of retired individuals destined for a cruise ship experience. And KLM flight 4805 originated in Amsterdam, bore 249 passengers destined for the beaches. Both aircraft were scheduled to land at Gando Airport on Grand Canaria Island.
Terrorism
The first challenge presented to the airmen was that their flights were diverted because of terrorist activities at Gando Airport on Gran Canaria. A violent faction of the Canary Island Independence movement phoned airport authorities and told them that they had planted bombs in the airport terminal, after evacuation one exploded in the florist shop. Concerns of additional bombs kept the airport closed for some time, while security personnel searched the airport.
KLM flight 4805 inbound from Amsterdam and Pan American flight 1736 coming from Los Angeles and New York were diverted to Tenerife’s Los Rodeos Airport, which was barely adequate to manage such large aircraft. About 50 planes were diverted to the small airport, so the taxiways were filled with aircraft, rendering the small airport even less effective. It is worth noting that Pan Am flight 1736 had enough fuel on board to establish a holding pattern and requested to stay in the air, rather than land on Tenerife. This request was denied by air traffic control.
One of the primary logistical stressors for the KLM pilot and crew was that they were scheduled to drop off vacationing passengers and pick-up travelers returning to Amsterdam the same day, with no change in flight crew. This itinerary coupled with the delay, put the crew at risk of exceeding the number of hours they were allowed to be on duty. Breaking duty rules came with severe penalties. This challenge presented a choice to Captain Jacob Van Zanten of the Dutch jumbo jet. His choice was to accept the possibility of delay at a cost to the airline for feeding and housing passengers or deny the possibility of delay and do his utmost to mitigate the cost.
Technical Problems
As they waited, KLM pilot Captain van Zanten decided to use his time effectively and refuel, thinking that topping up was a task that would need completion later on, for their return trip to Amsterdam. To refuel, whilst in the grip of a delay made sense. Shortly after his refuel decision was made, Gando airport on Gran Canaria opened. The commitment to refuel was irreversible and KLM was stationary on Tenerife for an additional 30 minutes. The Pan Am aircraft could not depart either, because it was behind the Dutch 747 and there was not enough room to get by. With so many aircraft clogging the airport taxiways, the planes needed to use the runway as a taxiway. This presented a potential deadly hazard that needed to be managed with great care. The airport also did not have ground radar, or runway lights. Everyone was blind and reliant solely on radio communications, if visibility became a challenge. Radios have a key flaw in that only one person can speak at a time.
Weather
As time ticked by with the refuel, the clouds rolled in, and the possibility of being trapped on Tenerife by weather was bearing down on the pilots. By the time KLM was finished refueling and began their taxi for take-off, visibility at the airport was closing in on the minimum sight distances needed to take off (without runway lights). As the KLM jet arrived at its’ take off position, they could no longer be seen by the tower, nor could the aircraft see each other. With pilots taxiing and taking off on the same strip of pavement, limited visibility, the pressure to depart, the stage was set.
Technical Problems (Continued)
In the fog, the pilots and ATC (Air Traffic Control) personnel were completely reliant on verbal communications. Radio communications, as we have said, have one critical flaw, heterodynes. If two people communicate at the same time on the same frequency, the result is an auditory squeal and the verbal information communicated is rendered inaudible. At a critical moment, when the KLM plane began rolling down the runway for take-off, Pan am communicated that they were still on the runway at the same time that the tower communicated. This was audible in the KLM cockpit only as a squeal. There were more communications with Pan Am and the Tower, but the KLM jet was already on their take of roll.
Human Factors
Denial / Acceptance
When one chooses to deny a situation, others or oneself, energy goes into the denial and we are no longer open the realities of the situation. In this mindset we no longer capture live information, so therefore we have a diminished ability to respond appropriately to the demands of the situation. In a denial mindset, we put energy into a construct we hope to make happen or wish would happen, rather than what is actually happening within ourselves, with others and in the environment or situation. When we want something different than what is happening, we make inappropriate choices for what is actually happening.
There are a number of recorded events that indicate that this was a likely mindset of Captain van Zanten.
Denial of the Situation
Captain van Zanten seemed deny even the possibility of delay. He seemed to be doing everything in his power to avoid being delayed. He calculated his duty time, refueled, and tried to make up time wherever possible, including breaking take off protocol, which I will address further along. Some of these actions are fine because we need to help the situations along. However, the important question is: did he ever accept the possibility of delay? This is a critical question because, if the possibility of delay was not option to him, then his perceptions would narrow. In denying the possibility of delay outright, it means that all of his decisions were generated from a “this must happen” mindset. This mindset is known as tunnel vision. In high consequence situations, narrowing perceptions means that critical inputs of information can be overlooked. This feature of denial seems apparent in van Zanten’s actions.
Victor Grubbs, however, seemed like he did accept the possibility of delay. He was willing to wait at the very end of the runway, so that he could mitigate the risk of being exposed to a collision with the KLM plane, but the tower requested that they taxi behind KLM.
Denial of Protocol
From the Cockpit voice recorder and the flight data recorder it is clear that the KLM pilot, van Zanten, started his take off roll without air traffic control (ATC) clearance, or runway clearance.
After completing the 180 turn at the end of the runway, Captain van Zanten begins “advancing his thrust levels”. He is stopped by his first officer Meurs, who says,
“Wait a minute, we do not have ATC clearance.”
Van Zanten throttles back to idle and says,
“I know that, go ahead ask.”
Meurs radios in a request for ATC clearance;
“Eh. . .the KLM four eight zero five is now ready for takeoff and eh. . we are waiting for takeoff clearance”
The tower responds;
“KLM eight seven * zero five uh you are cleared to the Papa Beacon climb to and maintain flight
level nine zero right turn after take-off proceed with heading zero four zero until intercepting the
three two five radial from Las Palmas VOR. (1706:08.2)” (*wrong call sign)
Meurs responds;
“Ah roger, sir, we're cleared to the Papa Beacon flight level nine zero, right turn out zero four zero
until intercepting the three two five and we're now (at take-off). (1706:17.9)”
Part way through Meur’s response to the tower, Captain van Zanten says, “Yaa” begins advancing his thrust levels for takeoff again and says,
“Let’s go. Check thrust.”
Van Zanten accelerates without runway clearance.
The tower communicates,
“Okay. . .standby for takeoff I will call you”. (Heterodyne)
Pan Am first officer Robert Bragg at the same time says,
“We are still taxiing on the runway clipper 1736” (Heterodyne)
There is only an audible squeal in the KLM cockpit
Denial of Others
KLM Captain van Zanten (KLM) does not effectively use the perceptions of his crew to guide his decisions. He denies their perceptions, convinced that his perceptions are correct. The following exchange between the tower, Pan Am and within the KLM jet illustrate the Captain’s denial of others.
The tower communicates to the Pan Am,
“Papa Alpha one seven three six, report runway clear.”
Pan Am first officer Bragg confirms,
“Okay, we’ll report when we are clear.”
KLM Flight engineer, Willem Schreuder says,
“Is he not clear then?”
KLM Captain van Zanten says,
“What did you say?”
Schreuder says,
“is he not clear, that Pan American?”
Captain van Zanten says,
“Oh Yes!”
Eleven seconds later van Zanten sees the Pan Am plane and pulls back on the yoke of the aircraft hard leaving 20m of tail strike on the runway and says,
“Goddamn it”
The KLM aircraft lifts off the runway and nearly clears the Pan Am jet, but hits the landing gear and engines, taking off the top tier of the aircraft. The KLM plane continues to fly for only 100m then it exploded in a fireball killing everyone on board.
Denial of Self
It seems that the Pan American Captain, Victor Grubbs understood the hazards of what was happening and failed to support his own perceptions. There are three things that happened that indicate that he denied his own better judgement. First, his aircraft had enough fuel on board for a holding pattern, but he followed air traffic controls instructions to land on Tenerife. Second, he did not want to taxi behind KLM, he wanted to wait until the jet took off and he denied his own better judgement here and listened to air traffic control instructions to follow KLM. Third, in the cockpit, just before the collision, the crew commented on how impatient the KLM Captain was, yet they did not come up with a strategy to mitigate the hazard of the situation.
Both KLM first officer Meurs and flight engineer had different perceptions than Captain van Zanten. They queried the captain, but they needed to follow through with their perceptions.
Denial of the Environmental Conditions (Situation).
Weather conditions, lack visual communication, the stress of timing were all mounting to the point where the prudent thing to do would be to accept that a delay would be inevitable. The conditions were speaking to the pilots. Conditions are something to be heard, rather than overcome. Captain van Zanten denied hearing what the environment was saying to him.
Denial of Consequence
One of the things that can be easy to forget is the gravity of the situations we are in when we lead others. To weigh the true consequence of a worst-case scenario. It seems apparent that one of the failures of both flight crews was to actually accept how important their decisions were in real ways, to the passengers on board their flights. The cost of an overnight, when weighed against the cost of making a fatal error is obvious. How often do we forget to factor in the worst case scenario, in our decision making processes?
Acceptance / Denial Conclusions and Lessons.
1) Accept the Situation: Being able to accept the possibility of delay is critical in keeping options and perceptions open.
2) Accept Protocol: Understanding and accepting that flight protocol is based on hard lessons learned is of critical importance. It is apparent that, captain van Zanten’s simulator experience worked against him. He was ATC in the simulator. However, I am sure that he instructed protocol to his pilots.
3) Accept Others: One of the great values of working with a team is that we can reduce our blind spots. Each of us has a field of view. We broaden the collective field by including other’s perceptions.
4) Accept Ourself: Our own better judgements, listen to our higher inner guidance and take action on those better judgements. This seemed apparent not only for Captain Grubs but also for the KLM first officer and the flight engineer. This of course led to changes in cockpit culture.
5) Accept Awareness of Consequence: As a leader of people in high risk situations, it is critical that we accept that people’s lives are in our hands and the worst case scenario can happen based on our choices. This awareness can help us make more dillegent choices.
Watch for Next Friday’s Post
References
HTTP://www.historynet.com/disaster-on-tenerife-historys-worst-airline-accident/
https://aviation-safety.net/database/record.php?id=19770327-1
https://www.faasafety.gov/files/gslac/courses/content/232/1081/finaldutchreport.pdf
https://www.historynet.com/disaster-on-tenerife-historys-worst-airline-accident/?f
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