With a sudden mass failure of oxygen regulators at over 8,000 meters on Everest, climbers suddenly lost their ability to continue their ascent – and only quick action and a rapid descent saved them from worse.

Climbers are now pre-acclimatizing in hypoxia tents, begin using oxygen at lower levels, and turning up their oxygen flow rates. Then they move quickly up in altitude, hoping to tag the summit and return as fast as possible. All well and good, as long as everything goes perfectly – a rare occurrence with the many variables on Everest.

When you leave your high camp on Everest, you will have a very carefully calculated amount of oxygen, delivered at a carefully monitored flow rate. More oxygen means carrying more weight, so at some point it becomes self-defeating. And more oxygen means more Sherpa’s. And so it relies on additional factors all working together: that the Sherpa’s will be close by, that your tanks have what they say in them and the flow rate is constant and calculated to last the distance, plus a bit more.

As less experienced climbers look for ever faster and easier ways to summit Everest, and guiding companies look for ever more technology to assist, the chance of getting in more trouble up high has rapidly escalated.

For many years it was a point of pride to reach the South Col without using oz, then turn it on to go for the summit. That soon slipped down to climbing up and sleeping at Camp 3 at 7,000 meters without oxygen. Now, it is not uncommon to see people walking out of Camp 2, fully laden with masks and bottles all dialed in.

All would be fine as long as all works perfectly – but as we have seen, even with the best available systems, run by the most experienced teams, all can quickly go badly wrong.

And for a climber who has followed a minimal acclimatisation program, has less climbing experience and suddenly finds their most vital ingredient failing on a windswept ridge at -20c in the dark, they will very quickly realize they are a very long ways from home.