On our final abseil, after two days of abseiling, an abalakov thread pulled through. We had overlooked clipping in the back-up screw with the result that Simon fell about 100m breaking 5 ribs and crushing 2 vertebrae.

We are both very experienced and tiredness/exhaustion was the underlying cause of the accident. Normal tiredness was much exacerbated by us poisoning ourselves on gone-off freeze-dried food during the climb. At the time of the accident we had been on half rations for 4 days and were on our third day with no food at all.

Our 22cm abalakov screw had broken earlier in the trip and we were using a 16cm screw to make the threads. This meant they were thinner than we would have liked. Also we had used up all our abseil tape and were using thin prussic loop cord which probably increased strain on the thread. We had tested the thread with a strong outward pull but that obviously wasn’t a good enough test. That said the ice was rather wet and that should have alerted us to possible weakness. Not clipping the back-up screw into the thread can only be put down to tiredness/exhaustion brought on by lack of food.