What is the fitness-to-fly test?
The fitness-to-fly (hypoxic challenge) test is used to see whether you need extra oxygen on an aeroplane or at high altitude.
If you live with a lung condition, the oxygen levels in your blood may be lower than normal. During a flight, the oxygen level in the cabin air is much lower than the air you breathe on the ground. This means that your blood oxygen levels can fall even further. This could result in heart problems or other complications. Using extra oxygen can help you avoid this.
If you’re planning to travel on a plane, ask your healthcare professional if you need this test well in advance of your trip. This will help you to plan and prepare for your trip.
Can I have the fitness-to-fly test on the NHS?
The fitness-to-fly test is not usually available on the NHS. You can ask your healthcare professional for more information about the costs of this test and how to get a referral.
What happens during a fitness-to-fly test?
Your healthcare professional will start by taking a blood sample. This is to measure the level of oxygen in your blood.
You’ll then put on a face mask and breathe in a low oxygen mixture. Your oxygen levels and heart rate will be monitored. The test usually takes between one to two hours.
If your oxygen levels go down during the test, your healthcare professional will add extra oxygen to see if your oxygen levels go back to normal.
Younger children may sit in a large cabin designed to be similar to an aeroplane cabin. The cabin has a lower oxygen mixture rather than using a face mask.
What do the results mean?
At the end of the test, your doctor will decide if you need oxygen during your flight. If your healthcare professional was able to bring your oxygen to a stable level, they’ll know the amount of extra oxygen you need to be able to fly safely.
If your oxygen goes down during the test, even after adding extra oxygen, it may be unsafe for you to fly.
If you already have oxygen therapy, you will need additional oxygen in flight. Ask your health care professional about this.
Your healthcare professional will tell you how long your result can be used for. Usually, you will not need to be re-tested if your lung condition stays the same.
For more information about flying with oxygen, have a look at our travel page.
Get support
Call or email our helpline for support with any aspect of living with a lung condition – whether you need practical advice, emotional support, or answers to health-related questions. You can also find support through our groups.
