SAFA Skysailor Magazine

49 SPRING 2025 | September-October-November SKY SAILOR in a lowered oxygen partial pressure compared to sea level, and not having a supplemental oxygen supply can lead to hypoxia. While hypoxia is generally regarded to be occur at altitudes above 10,000ft AMSL, there are factors at the individual level that will lead to onset at lower altitudes. Pilots vary physiologically and so it is difficult to quantify onset at the individual level. Physical activity at altitude means an increased requirement for oxygen and will lead to more severe symptoms. A pilot’s level of fitness has an effect – fitter people are more tolerant of hypoxia. Diseases af- fecting the heart, lungs or blood will affect the ability to oxygenate and transport blood. Also, a person’s emotional state, whether anxious or apprehensive, can make them more susceptible. The rate of ascent and duration at altitude will contrib- ute to the speed of onset and severity of the symptoms. It is important to note that the effects of hypoxia are cumulative – the longer you are there, the more severe the symptoms that will develop. Acclimatising yourself to higher altitudes will contribute to tolerance. Probably the biggest contributing factor though is smoking. Smokers incur a 5000ft penalty straight away. If you’re flying at 8000ft AMSL, the effect is equivalent to being at 13,000ft AMSL. Recognising the symptoms and measuring SPO2 The onset of hypoxia is insidious; people suffering do not realise they are affected. So how do we recognise it? The symptoms in increasing significance include breath- lessness, excessive yawning, tiredness and fatigue, euphoria, impairment of performing learned and mental tasks, change in sense perception and eventually unconsciousness. To get an idea of the types of behaviours hypoxia induces, have a look at these: youtube.com/watch?v=n_MI9UiYwJA youtube.com/watch?v=kUfF2MTnqAw youtube.com/watch?v=XnOAnVTyC-E How can we measure oxygen saturation in the blood? In hospitals you will see staff slipping a device attached via a cable to a monitoring and readout device, onto the fingers of patients. This device emits infrared and glow from two light sources