Wednesday, 4 July 2012

An accident: lots of factors, no blame

At one level, this is a story that has been told many times already, and yet this particular rendering of it is haunting me. I don't know all the details (and never will), so parts of the following are speculation, but the story is my best understanding of what happened, and it highlights some of the challenges in trying to make sense of human error and system design.

The air ambulance made a tricky descent. Although the incident took place near a local hospital, the casualty was badly injured and needed specialist treatment, so was flown to a major trauma centre. Hopefully, he will live.

What happened? The man fell, probably about 10 metres, as he was being lowered from the top of a climbing wall. It seems that he had put his climbing harness on backwards and tied the rope on to a gear loop (which is not designed to hold much weight) rather than tying it in correctly (through the waist loop and leg loop, which were behind him). Apparently, as he let the rope take his weight to be lowered off from the climb, the gear loop gave way.

I can only guess that both the climber and his partner were new to climbing, since apparently neither of them knew how to put the harness on correctly, and also that there was no-one else on the wall at the time (since climbers generally look out for each other and point out unsafe practices). But so many things must have aligned for the accident to happen: both climbers must have signed a declaration that they were experienced and recognised the risks; the harness in question had a gear loop at the centre of the back that they could mistake for a rope attachment point... but that loop wasn't strong enough to take the climber's weight; someone had supplied that harness to the climber without either providing clear instructions on how to put it on or checking that he knew...

So many factors: the climber and his partner apparently believed they were more expert than they actually were; the harness supplier (whether that was a vendor or a friend) didn't check that the climber knew how to use the equipment; there weren't other more expert climbers around to notice the error; the design of the harness had a usability vulnerability (a central loop that actually wasn't rated for a high load and could be mistaken for a rope attachment point); the wall's policy allowed people to self-certify as experienced without checking. Was anyone to blame? Surely not: this wasn't "an accident waiting to happen". But the system clearly wasn't as resilient as it might have been because when all these factors lined up, a young man had to be airlifted to hospital. I wish him well, and hope he makes a full recovery.

The wall has learnt from the incident and changed its admissions policy; hopefully, there will be other learning from it too to further reduce the likelihood of any similar incident occurring in the future. Safety is improved through learning, not through blaming.

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