Fit-to-fly test

What is a fit-to-fly test?

A “fit-to-fly” test is a simple procedure performed to give the doctor accurate information about your blood oxygen levels in an aeroplane.

Why do I need to have this test?

Your doctor has asked that you have this test to determine whether you need additional oxygen when you are in an aircraft. This is because there is less oxygen available in an aircraft and the result of your blood oxygen level may indicate that you will need additional oxygen during flights.

What happens during the test?

Before the test begins the Physiologist will explain the test to you in detail and will answer any questions that you may have.

For the duration of the “fit-to-fly test” test you will be seated. A probe will be put on your finger. This will provide us with information about your blood oxygen levels.

As part of the test it is also necessary to take several pinpricks of blood from your earlobe to provide further information about your blood oxygen levels.

The test will take approximately 90 minutes to complete. The length of the test may vary slightly depending on the initial blood oxygen level, as it may be necessary to give you low level oxygen to simulate the flight environment.

Important information

  • Please continue to take all medications as normal.
  • Please do not wear nail varnish to your appointment.
  • You are advised not to book or pay for any flights until you have had the results of this test.
  • It is very dangerous to go on a flight if you have been advised against this. You could experience serious breathing difficulties.

Thank you for your co-operation. This will assist us in obtaining accurate information and enable us to provide you with the most appropriate treatment.

Frequently asked questions

Will I experience any discomfort or side effects?

The only discomfort you may experience is a slight scratch on your ear when a pinprick of blood is taken. There are no known side effects associated with this test.

Is there a different test I could have?

There is no other test that would give us this information about your blood oxygen levels.

When will I be told the results of my test?

You are usually told your results at your next clinic appointment, or a letter may be sent to your GP or the doctor who referred you for the test.

What should I wear when I attend for my test?

You should wear normal comfortable clothing.


British Thoracic Society Standards of Care Committee (2002) Managing Passengers with Respiratory Disease Planning Air Travel. London: British Thoracic Society.

NHS Constitution. Information on your rights and responsibilities. Available at

If you or the individual you are caring for need support reading this leaflet please ask a member of staff for advice.

How to contact us:

Respiratory Physiology
Gate 12
Level 1
Brunel building
Southmead Hospital
BS10 5NB

0117 414 5400 Monday to Friday, 8am to 6pm

© North Bristol NHS Trust. This edition published April 2021. Review due April 2023. NBT002290

Fit-to-fly test