The danger of oxygen deprivation
Above all else in the team’s planning, there is one critical factor: oxygen. The danger of ascending into such rarefied air is having a malfunction with the oxygen systems that the pilots are breathing and depending on so heavily. The pilots will be using state of the art aviation breathing systems, and will have been pre-acclimatised over six weeks back in the UK on special re-breathers called Hypoxicators. This is all to prepare for their ascent from 11,600 feet to 33,000 feet, and to put them in the best possible position should a malfunction occur and the pilots find themselves stranded high on a Himalayan mountainside.

This pre-acclimatisation will enable them to survive without additional oxygen up to 22,000 feet. Above this height, if there is an oxygen problem the danger is going hypoxic – a condition brought on very rapidly, within a minute or two, by a lack of oxygen in the body. This results in unconsciousness and death. The pilots must keep a ‘weather-eye’ on their oxygen regulators at all times to make sure the flow is always running correctly. This air flow is their life-line.

This is also why communication between the pilots throughout the climb is so vital. It enables them to spot the symptoms of hypoxia and to be able to do something about it. In the pilot’s case, there is only one solution: descend, descend, descend. This is why it is so vital that the pilots have enough altitude before they venture towards Everest itself, or even over the Nuptse Wall – without it they would be unable to glide away from the high mountains and spiral quickly down to a ‘safe’ working altitude in the event of an oxygen malfunction.

The team will also be training together back in the UK in a specially designed hypoxic chamber that simulates the rare air of high altitude, so that they can recognise the symptoms of hypoxia in each other and themselves.