• Aviation
• Hypoxia

In 2019, a record 4.5 billion passengers travelled by air.1 This fell markedly during the COVID-19 pandemic, but in 2023, the industry’s measure of overall airline ‘traffic’, revenue passenger kilometres, was back to 94% of the 2019 figures, with predictions that 2024 will see new record passenger numbers (see figure 1).2 This highlights how common air travel is and reinforces the idea that it is highly likely that all doctors will see patients who travel by air. However, passenger fitness-to-fly considerations are not typically covered in undergraduate medical curricula or postgraduate medical specialty training programmes. This was recognised as an area of deficiency in clinical training and support to the general population by the House of Lords Science and Technology Committee.3 In response, the UK Civil Aviation Authority set up an Aviation Health Unit, which acts as a focal point for aviation health in the UK, providing information for passengers and guidance for health professionals on assessing the fitness of their patients for travel by air.4 These efforts also contributed to the establishment of the specialty of Aviation and Space Medicine, which was approved by the General Medical Ccouncil in 2016.5

A key consideration around passenger fitness to fly is the potential interaction of the air travel environment with normal physiology or pre-existing …