The Tenerife Disaster of 1977: “We’re Going”

Tenerife, the power gradient, and the calculus of voice

On 27 March 1977, two Boeing 747s collided on a runway in the Canary Islands, and 583 people died. It is still the worst disaster in the history of civil aviation, and it happened on the ground, in fog, between two aircraft that weren’t actually supposed to be there.

Neither flight was scheduled to land at Los Rodeos. They were bound for Gran Canaria, until a separatist group detonated a bomb in the terminal there and a warning of a second one closed the airport. All flights headed to Gran Canaria were diverted, and many of them were sent to Los Rodeos on Tenerife: a small airport on a saddle between two mountains, with a single runway, a handful of taxiways, one apron, and a local reputation for being foggy. By the afternoon the apron was full of diverted widebodies, and the taxiways were blocked by the aircraft parked on them. When the all-clear finally came, the planes that wanted to leave could not taxi around to the runway in the ordinary way, because there was no room. They had to taxi down the active runway itself, turn around at the far end, and take off back the way they had come.

Speaking up on the flight deck

The KLM 747 was piloted by Captain Jacob van Zanten, with First Officer Klaas Meurs beside him and Flight Engineer Willem Schreuder behind. Van Zanten taxied the length of the runway, turned the aircraft 180 degrees, and got ready to depart. Behind them, the Pan Am 747 was still taxiing down the same runway, under instruction to turn off at the third exit. 

Van Zanten advanced the throttles. Meurs, somewhat surprised, told him they did not yet have ATC (air traffic control) clearance. Van Zanten brought the power back and, by the report’s account, told him to go ahead and ask for it. Meurs did speak up, and van Zanten did respond. 

The ATC tower then passed KLM a route clearance, the instructions for after departure, and it contained the word “takeoff” without actually being a clearance to take off. Meurs read it back and tailed off with the words “we are now at takeoff.” Van Zanten, already releasing the brakes, said two words over the top of him: “We’re going.” The controller, who could not see the runway, answered “OK,” and then, after a pause, “stand by for takeoff, I will call you.” At that exact moment the Pan Am crew keyed their microphone to say they were still on the runway. The two radio transmissions collided, producing a squeal that meant neither were audible. The only word that reached the KLM cockpit cleanly was “OK.”

The tower then told the Pan Am to report when it was clear of the runway, and Pan Am acknowledged. This much was audible in the KLM cockpit, and Schreuder heard it. He then asked the question that should have prevented disaster: “Is he not clear, that Pan American?” Van Zanten answered, emphatically, “Oh, yes.” Schreuder asked again. He was answered again, with the same certainty, and Van Zanten increased the throttle, accelerating the 747 along the runway.

And then both Schreuder and Meurs were quiet. For the ten or fifteen seconds that remained they said nothing, until the fog ahead cleared, at about 160 miles an hour, showing the Pan Am 747 directly in their path, pointing straight at them. Both crews tried to take evasive action. The Pan Am hauled left toward the grass verge beside the runway; whilst van Zanten pulled back hard enough to drag the tail along the tarmac, trying to take off straight up and over the Pan Am. However, Van Zanten had decided to refuel during the long wait, sensibly enough, and combined with the full complement of passengers and luggage, it meant the KLM was heavy, and they didn’t quite make it. The wheels and one engine of the KLM ripped into the Pan Am, and the KLM aircraft hit the ground at speed. The collision killed everyone aboard the KLM and most of those aboard the Pan Am. 583 people died as a result.

“But if it really matters, won’t people speak up?”

If we take one thing from this, it is this: people do not speak up with their concerns, and they especially do not speak up again once they have spoken up and been dismissed, even when their own lives and the lives of others are at stake. The interpersonal costs and risks of speaking up loom so large that they outweigh the benefits of doing so.

Willem Schreuder was not junior or inexperienced. He had more flying hours than either of the men in cockpit with him. He had seen the problem and named it, twice. And then, having watched his certainty bounce off the captain’s certainty, he stopped, in an aircraft accelerating along a runway he had good reason to think was occupied by another plane. This is not cowardice or stupidity. It is what the interpersonal cost of voice does to all of us.

Consider the tacit calculus of voice, combined with Prospect Theory: we weigh the almost certain cost of speaking up against a merely possible benefit. The cost of pressing the captain a third time is immediate, social, and certain. You will be the person who second-guessed the chief instructor, out loud, on the basis of a feeling, and if the runway turns out to be clear you will have aborted his takeoff for nothing. The benefit is probabilistic and invisible if it works: a collision that does not happen leaves no trace and earns no credit. We all tend to over-estimate the immediate costs of speaking up, especially against someone senior, so the calculus tips towards the negative and we remain silent. This is all very human.

And notice the form the doubt took. Schreuder did not say “there is an aircraft on that runway, stop.” He asked whether the Pan Am was clear. This isn’t incidental: crews, and especially the less senior, tend to raise concerns in mitigated forms, as hints and questions rather than statements and commands, and the softer the form, the easier it is to wave away (Fischer and Orasanu, 1999). The same calculus that pushes us toward silence also shapes how we say something.

Here’s the really uncomfortable bit though – if the calculus still tips toward silence when the downside is death, in an aircraft, with your own life in the balance, then we should not be remotely surprised that it tips toward silence in a marketing meeting, an ideation session, or a finance catch-up. In most of the meetings and conversations we have, nobody is about to die. The high stakes that might justify the risk of speaking are not even close to this example, which means the silence makes even more sense. Tenerife is not a rare case at the edge of human behaviour. It’s an ordinary case, but with a tragic outcome.

The Power Gradient

The second thing this disaster surfaced, along with the others that the human-factors investigators were studying around the same time, was the gap in power between the most powerful person in the space, and the least. The aviation safety literature of the period called it various things, the authority gradient, the cockpit gradient, the trans-cockpit authority gradient, the power gradient. They are all pointing at the same structural feature: the steeper the difference in power between the person at the top and the person who has something to say, the harder it is to say it. This isn’t only intuitive: it shows up in the data on how status differences shape cockpit communication and coordination (Milanovich et al., 1998). The steeper the gradient, the more that voice is suppressed – it’s much harder to speak up against someone with greater power – power over your future, your reputation, your job, or your status. This is in fact, one of the most important things, perhaps the most important thing, governing whether people speak up.

“Power” is a large and ambiguous word though, so it helps to break it down. Drawing on French and Raven, but trying to make it usable rather than academic, we can talk about four kinds of power.

Formal power (positional power) is the obvious kind, the kind that is described and written down. Role, rank, title, seniority; where we sit in the org chart, how many people report to us, who we report to, which rules and structures are ours to invoke. It is the most legible form of power, and being legible, it is also the easiest to see and to navigate around.

Informal power is much harder to see, because it is almost never written down. It lives in social standing, reputation, popularity, the size and shape of our networks, our reputation, how many people we know and how well. It does its work invisibly, which makes it harder to name and harder to navigate.

Demographic power is mostly the power we did nothing to earn and cannot hand back: height, race, age, gender, sexuality, class, accent. It endows, or otherwise, different degrees of power in different contexts.

Expert power is what we know: our qualifications, our experience, our demonstrated competence in this domain. It is sharply contextual. A brain surgeon in a cockpit has very little of it (probably, maybe they’re also a qualified pilot). An experienced surgeon in an operating theatre has a lot of it. 

The point of separating these out is that they do not behave as one thing. They can pull against each other, they can compensate for each other’s absence, and, dangerously, they can stack up.

In van Zanten they all stacked up. His informal power was enormous: he was the face of KLM’s advertising, the man in the in-flight magazine, photographed under the line about the people who made punctuality possible. He was, at least in the world of the airline, a minor celebrity. His demographic power was high as a tall, tanned, silver-haired Dutchman in a captain’s uniform. His expert power was as high as it goes: he was KLM’s chief instructor on the 747, the man who taught other pilots how to fly the aircraft, the airline’s recognised authority on the type. And his formal power matched it, the seniority and standing of the chief of flight training, the man KLM would later try to reach to help investigate the crash, before they realised that he had been at the controls. He had also, only weeks earlier, conducted Meurs’s qualification check on the 747. The first officer beside him owed his certification on the aircraft to the man he was trying to challenge.

Set that out and the gradient in that cockpit is incredibly steep, along every axis.

It is worth being careful here, because the easy version of this story makes van Zanten a powerful tyrant, and the evidence doesn’t support it; in fact rather the opposite. Colleagues who knew him, including Jan Bartelski, a fellow KLM captain and later president of the international pilots’ federation, dispute that portrait flatly. By their account he was studious and introverted but warm, a believer in partnership who insisted his first officers call him “Jaap” rather than “Captain.” This doesn’t weaken the argument; in fact it reinforces it. The power gradient did its silencing work in the cockpit of a man who, by temperament and by stated belief, was trying to flatten it. The gradient is not mainly a matter of personality. It forms between people, out of their positions relative to one another: rank, reputation, expertise, and how readily the room defers. None of that dissolves because the person at the top is, personally, a good sort. We might work to mitigate the gradient, and we should; but the gradient remains.

None of which is to say it was his fault, or that having power is something to feel guilty about. We may possess a great deal of power and that is fine; most of us will, in some room at some time, be the most powerful person in it. What we are obliged to do is recognise and acknowledge it, because the gradient forms whether or not we want it to, and it has effects whether or not we intend them. And the gradient acts on the powerful, too. A reputation built entirely on being on time every time is a reputation with a downside, and a man already badly delayed, watching the duty clock run down, was under a pressure of his own making to go. The punctuality that sold his reputation was pressing on the throttle in his hand on the runway.

What we learned from the wreckage

The lasting answer to Tenerife, and to the accidents around it, was Crew Resource Management. It came out of a NASA workshop on human factors in 1979, which itself was catalysed by the Tenerife disaster, along with others, and was first adopted comprehensively by United Airlines in the early 1980s, and was taken up by nearly every airline in the world within a remarkably short time. It is, with some justification, often called the most successful safety programme humanity has ever created. It is a large part of the reason that getting into an aeroplane is now one of the safest things you can do.

CRM emerged in aviation specifically to reduce catastrophic errors by changing cockpit culture: communication norms, authority gradients, briefing practices, and coordination under pressure. It was quickly adopted in medicine, especially in emergency response and (surprise) surgical teams. It trains people to speak up when something looks wrong, to challenge respectfully, to cross-check decisions, and to share situational awareness. In doing so, it creates a structured environment in which speaking up becomes expected and legitimate (Weller, Boyd and Cumin, 2014). The sense that it is safe to raise a concern is not a mysterious precondition that must somehow appear in advance. It is the result of concrete practices, training, and norms that make voice a normal part of the work.

It began life as Cockpit Resource Management and became Crew Resource Management, as a result of further disaster and our learning from them. Accidents like Kegworth, where cabin crew outside the cockpit could see things the pilots could not and the information never made the journey forward – due to a steep power gradient between cockpit crew and cabin crew, taught the industry that it is not enough to train only the people at the controls. Cabin crew, ground crew, air traffic control, operations staff: everyone in the system needs to be able to speak up to power at the moment it matters, and everyone needs the people above them to listen when they do. The safest crews are the ones where leadership is, in effect, shared: cabin and cockpit prompting and correcting one another rather than information travelling in one direction (Bienefeld and Grote, 2014).

CRM works on the problem from both ends. It scaffolds the act of speaking up against a gradient, giving people recognised, legitimate ways to push information upwards. And it works on the gradients themselves, building in practices that share power and distribute authority so that the slope is shallower before anyone has to climb it. Both are necessary. We cannot only teach the person at the bottom to be braver; we also have to lower the wall. None of this is a switch we flip once. Safety silence persists even in trained crews wherever the local culture quietly licenses it, which is why CRM has to be lived rather than merely delivered (Perkins et al., 2022).

Walking ourselves up the ladder

One of the practices that came out of this world is PACE, a graded assertiveness tool, and it is worth walking through because it is a scaffold built precisely for the moment Schreuder found himself in.

We begin with a Probe: a low-threat question that surfaces the concern without confronting anyone. “Is that red light meant to be on?”, “That Pan Am, is he clear yet?” Schreuder’s question was, in effect, a probe. If the probe does not get traction, if it doesn’t draw attention to the thing we are actually concerned about, we escalate to an Alert, which names the hazard clearly. “Oxygen is at 90% and falling.” or “We don’t have ATC clearance for takeoff.” Meurs’s first objection was an alert. If the alert doesn’t land either, we go to Challenge: stating the problem and proposing a different course of action, which is much harder, because now we‘re not just raising a worry, we’re asking the powerful person to do something other than what they have decided. “I don’t think it’s safe to take off yet. There may be an aircraft on the runway. Let’s hold and check.” And if even that fails, we reach Emergency, an unambiguous command: “Stop. This is unsafe.” This is very interpersonally challenging and risky, but is less so if we’ve walked ourselves up the PACE steps already – and hopefully we don’t need to get to Emergency anyway.

At Tenerife, nobody got past Alert. Two experienced professionals raised the hazard, had it dismissed, and stopped where the ladder becomes more interpersonally expensive.

We see the same pattern far outside aviation. Elaine Bromiley died in 2005 during what should have been a routine operation, when her anaesthetists became fixated on an airway they could not secure and lost track of the time she had spent without oxygen. The nurses in the room could see what was happening. One of them had fetched the kit for an emergency surgical airway and had it ready. They did not speak up and directly challenge the anaesthetists however, because the gradient between nurse and consultant in that theatre was every bit as steep as the one in the KLM cockpit, and the calculus of voice tipped the same way it always does (Harmer, 2005). Her husband Martin, an airline pilot, went on to found the Clinical Human Factors Group, and has spent the years since bringing aviation’s hard-won human-factors lessons into healthcare.

The reason the ladder helps is not that the top rung becomes comfortable. Issuing an unambiguous command to someone who holds your future in their hands is never going to feel safe, and it is not supposed to. The point is that you very rarely have to start there. By beginning with a probe and escalating only as far as you need, you walk yourself up the slope one manageable step at a time, and most of the time the problem is resolved long before you reach the top. The ladder turns one impossible act into a sequence of difficult but possible ones. And it gives the people around you, the ones with the power, a recognised signal that something is wrong before it becomes a fight.

What Tenerife taught us

We have learned an enormous amount from this disaster, as we have from many others. The conditions that produced the silence in that cockpit are not rare or unique to aviation. A steep gradient, a respected expert who has just expressed certainty, a team under time pressure, a concern that gets raised and dismissed once: this isn’t just a description of a 1977 runway. It is a description of an ordinary Tuesday in a finance team, a weekly planning meeting with the boss, or any number of other, comparatively mundane, contexts (with the merciful difference that the stakes are usually lower). The silence itself is not a quirk of individuals but a collective condition, one that organisations produce and reproduce in themselves (Morrison and Milliken, 2000).

That difference is also the danger. Because the stakes are lower, the silence is cheaper, and the scaffolding that aviation was forced to build under the pressure of mass fatalities is scaffolding the rest of us never get round to building at all. If two skilled people would not press a third time with their own lives on the line, we cannot reasonably expect anyone to press in a meeting where the worst case is mild embarrassment, unless we have deliberately made the conditions possible. 

Jan Hagen’s Confronting Mistakes is a great book to read alongside this, because it works through the disasters of these decades and asks, of each one, why it happened, what might have prevented it, and what we learned from it. For the fullest blow-by-blow reconstruction of the accident itself, Admiral Cloudberg’s account is the best there is (Cloudberg, 2022). Underneath nearly all of them sits the same thing the human-factors investigators surfaced at Tenerife, decades before psychological safety became a term anyone outside a few corners of academia would recognise. They weren’t using the term psychological safety (because it wasn’t yet in mainstream use), but they were describing the exact same thing. The gradient suppresses voice; the silence risks disaster; and the work is to build the conditions, structural as well as interpersonal, in which the least powerful person in the room can say the thing that needs saying while there is still time to act on it.

Van Zanten’s last two words on the matter were “We’re going.” Everyone else acquiesced.

References

Bienefeld, N. and Grote, G. (2014) ‘Shared leadership in multiteam systems: How cockpit and cabin crews lead each other to safety’, Human Factors, 56(2), pp. 270–286.

Cloudberg, A. (2022) ‘Apocalypse on the Runway: Revisiting the Tenerife Airport Disaster’, Medium, 1 January. Available at: https://admiralcloudberg.medium.com/apocalypse-on-the-runway-revisiting-the-tenerife-airport-disaster-1c8148cb8c1b (Accessed: 25 June 2026).

Fischer, U. and Orasanu, J. (1999) ‘Cultural diversity and crew communication’. Paper presented at the 50th International Astronautical Congress, Amsterdam, October 1999.

Harmer, M. (2005) The case of Elaine Bromiley. Available at: https://www.chfg.org/wp-content/uploads/2010/11/ElaineBromileyAnonymousReport.pdf (Accessed: 25 June 2026).

Milanovich, D.M., Driskell, J.E., Stout, R.J. and Salas, E. (1998) ‘Status and cockpit dynamics: A review and empirical study’, Group Dynamics: Theory, Research, and Practice, 2(3), pp. 155–167.

Morrison, E.W. and Milliken, F.J. (2000) ‘Organizational silence: A barrier to change and development in a pluralistic world’, Academy of Management Review, 25(4), pp. 706–725.

Perkins, K., Ghosh, S., Vera, J., Aragon, C. and Hyland, A. (2022) ‘The persistence of safety silence: How flight deck microcultures influence the efficacy of crew resource management’, International Journal of Aviation, Aeronautics, and Aerospace, 9(3).

Weller, J., Boyd, M. and Cumin, D. (2014) ‘Teams, tribes and patient safety: Overcoming barriers to effective teamwork in healthcare’, Postgraduate Medical Journal, 90(1061), pp. 149–154.