Glasgow helicopter crash: A rare risk but it makes sense to prevent a repeat

Psychologists and risk experts are always telling us that we fixate far too much on unusual dangers and not enough on the hazards that we confront every day. The Glasgow helicopter crash will no doubt provide another opportunity to highlight our supposed irrationality as people demand inquiries to avoid a repeat of an accident that killed at least eight people, while five people die every day on the UK’s roads.

But is it really illogical to worry about unusual causes of death and serious injury? I’m not convinced it is, and if I’m right, we need to take seriously many concerns about what on the face of it look like improbable calamities.

I first started thinking about this when I heard the scientist Jared Diamond tell a story of camping out with some Papa New Guineans. He thought they were being over-cautious when they refused to sleep under a dead tree for fear it would fall. But then he realised that even if the chances of being crushed were tiny, if you sleep out every night under dead wood, then in the long run you are inviting disaster.

Diamond draws the conclusion that we ought to worry about many things we do regularly that don’t appear very dangerous, like stepping into slippery showers or climbing ladders. He’s right, but not because we do these things time and again. All things being equal, anything that would be dangerous if done regularly should always be avoided, unless the risk is worth it or the alternative is worse.

It sounds counter-intuitive, but the logic can be made clear by analogy with the well-established gambler’s fallacy. The foolish gambler sees that a coin has been tossed three times in a row and so thinks it is more likely to come up tails next time. But the probability of each coin coming up heads or tails is the same on every toss. Each event is independent.

In a similar way, the risk of sleeping under a dead tree on any given night is identical for everyone, whether they have spent the last thousand nights under the stars or a roof. So if it is too dangerous for the Papua New Guineans, it is too dangerous for Diamond. And by extension, anything that carries the same risk is also too dangerous for anyone.

It’s a surprising conclusion, which is why I ran the argument by several risk experts. None disputed the basic logic, although several rightly wanted to stress that nothing is completely safe, and often the alternatives to running one risk are no safer. Nor is it rational to spend huge sums of money reducing tiny risks when the cash could be better used elsewhere. Also, a life of minimised risk would not be one of maximised potential. Most of us would rather confront the dangers of travel than limit our horizons to home and hearth.

Still, we have good reasons to take steps to avoid apparently rare and improbable catastrophes. Think, for instance, about how perilous it is to have a helicopter hover over an occupied area. As this newspaper reported on Saturday, a recent international helicopter safety symposium in the US put the helicopter accident rate at 7.5 per 100,000 hours of flying, which although much higher than the 0.175 for aeroplanes still sounds pretty low. But that’s the equivalent of one accident per 13,333 flying hours, or one every 555 continuous days of flying. In other words, if there were always a helicopter hovering above your town, then within two years you’d expect at least one to fall out of the sky, with death the likely result.

No one would tolerate such a high risk of dying without very good reason. Of course, if we never used helicopters in cities, people might die for not getting to hospital on time. But if there is not a pressing need to have choppers above homes and businesses, the risk is sufficiently high for a case to be made that they just should not be there. That should be the focus of any inquiry into the Glasgow crash, not the precise mechanical causes.

It is not silly to take seriously many risks that look low in stark numerical terms. If there are affordable, easy steps to avoid or reduce threats to life it would be mad not to take them. Bereavement is no easier for the cause of it being rare. If the losses of banning all but emergency helicopters from flying over densely occupied areas are low, why on earth would we not want to remove one more cause of human misery? This is not getting risk out of perspective: it’s seeing it for what it really is.

Julian Baggini has written several books about philosophy