Fit to Fly Letter in London 2026. Who Actually Needs One, What the Airline Will Accept and When a Hypoxic Challenge Test Comes First
The Wellness in Marylebone provides the best fit to fly assessment in London for people who need a letter an airline will accept, issued the same day by a doctor who has examined them, with the same-day video consultation from £150, the in-person consultation from £220, the medical letter from £150 and a hypoxic challenge test arranged at a specialist lung function unit where breathing is the question, inside a ladder that runs to £49,995. Most passengers do not need a letter and this page says who does. Cabin pressure at cruising altitude is equivalent to around 8,000 feet, which lowers blood oxygen in everyone and matters only in people whose oxygen is already low, and the British Thoracic Society recommendations on air travel set out who needs testing. A resting oxygen saturation below 95% at sea level, a recent pneumothorax, a heart attack within 10 days, a stroke within 10 days, abdominal surgery within 10 days or a pregnancy past 28 weeks are the situations where airlines ask for paperwork, and the Royal College of Obstetricians and Gynaecologists confirms uncomplicated pregnancy is safe to fly until 37 weeks. A letter issued without an examination is a piece of paper the airline can refuse, and we do not issue one. Fees appear further down this page.
Reviewed by the medical team at The Wellness. Last updated 1 September 2026.
Ask whether you need a fit to fly letter or email team@thewellnesslondon.com or call 020 3951 3429.
Who actually needs a fit to fly letter
Fewer people than ask. Airlines require medical clearance, usually through the IATA MEDIF form or their own version, when a condition could deteriorate in flight or need in-flight oxygen, not because a passenger has a diagnosis. The situations where a letter is routinely demanded are pregnancy from 28 weeks, any recent surgery, a plaster cast fitted within 48 hours, a recent heart attack, stroke, pneumothorax or chest infection, a need for oxygen or a nebuliser on board, and a condition that has changed since the ticket was booked.
Stable, well-controlled long-term conditions do not need a letter. A person with controlled asthma, treated blood pressure, well-managed diabetes or a pacemaker fitted more than a few weeks ago can fly without paperwork, and a letter confirming medication is only needed where liquids over 100 ml, needles or a controlled drug are carried through security. What every airline will refuse is a letter that does not state the diagnosis, the date of assessment and the doctor's registration, or one dated after the passenger was seen.
What the airline will accept
A fit to fly letter is a clinical document. It states the condition, the date you were assessed, the examination findings that support the opinion, the flight and dates it covers, any conditions attached such as in-flight oxygen or an aisle seat, the doctor's name and GMC registration, and it is signed on the day of the assessment. Airlines cross-check the registration, and several now ask for the letter to be dated within 7 days of departure.
For pregnancy, most UK airlines want a letter from 28 weeks confirming the due date, a single or multiple pregnancy and the absence of complications, and the RCOG guidance allows flying to 37 weeks in an uncomplicated singleton pregnancy and 32 weeks with twins. For surgery, the timings come from the British Thoracic Society and the Civil Aviation Authority. Around 1 to 2 days after keyhole surgery, 10 days after open abdominal surgery, 7 days after a simple fracture with a split cast, and around 2 weeks after a pneumothorax has fully resolved on a chest X-ray.
Tell us your condition and flight date and we will say what the airline needs or email team@thewellnesslondon.com.
When a hypoxic challenge test comes first
Cabin air at cruising altitude carries around 15% oxygen against 21% at sea level, and a healthy person's saturation falls to around 90 to 93% without noticing. Someone with COPD, pulmonary fibrosis, severe asthma or heart failure whose saturation is already 92% on the ground can fall to a level that causes breathlessness, confusion or worse. The British Thoracic Society recommendations say a resting saturation below 95% at sea level, or a condition that has needed hospital admission in the past year, needs assessment before flying rather than a letter alone.
The hypoxic challenge test answers the question directly. You breathe a gas mixture with 15% oxygen for 20 minutes in a lung function unit while saturation and, where needed, arterial gas are measured, and the result tells the doctor whether you can fly without oxygen, need oxygen at 2 litres a minute or should not fly yet. It is arranged at a specialist unit, reported by the respiratory team there, and the fit to fly letter is written when the result is back, with the oxygen requirement specified so the airline can arrange it.
Which fit to fly services should you not buy
A letter issued from an online form without a consultation is the first, because it does not state examination findings and the airline can refuse it at the gate, when there is no time to get another. A letter for a condition that does not need one is the second, and we say so rather than charge for it. A letter written for a condition the doctor cannot assess by video, such as a chest infection that needs the chest listened to or a surgical wound that needs to be seen, is the third, and those are seen in person.
A fit to fly letter for a passenger who should not fly is the fourth. A pneumothorax that has not been confirmed as resolved on an X-ray, a saturation below 85% on the hypoxic challenge test, unstable angina or a pregnancy with complications are not letter problems, and a doctor who signs them off is putting a name to a risk they have not managed. The consultation in those cases is about what needs to happen before the flight, and the letter follows when it is safe.
What does a fit to fly letter cost in London
At the top of the market, 12-month programmes with a retained doctor run to £49,995 and comprehensive health programmes exceed £32,000, where a fit to fly letter is written by the doctor who already holds your record. Harley Street consultations run £250 to £350 and a respiratory consultant first appointment £250 to £500 before any test or letter, and a hypoxic challenge test at a hospital lung function unit carries its own fee on top.
Beneath that sits a tier defined by its conditions rather than its price, online form services with no consultation, no examination and no doctor accountable when the airline questions the letter. At The Wellness the price includes the assessment, the letter written and signed on the day, and where a hypoxic challenge test is needed, its arrangement at a specialist unit with the letter issued when the result is back. All figures are from prices.
Principal Programme, 12 months, one individual, the fullest level of care, from £31,995
Continuous Care Programme, 12 months of oversight for one person, from £24,995
Executive Health Programme, the most comprehensive single assessment, from £11,995
Home, hotel or office visit, evenings and weekends, from £695
Home, hotel or office visit, daytime, from £495
Extended 45-minute consultation, from £395
In-person consultation, 30 minutes, from £220
Same-day video consultation, 30 minutes, from £150
Medical letter or certificate, following assessment, from £150
Why The Wellness is the best fit to fly assessment in London
Every letter follows an examination and states what was found, and that is countable. The diagnosis, the date of assessment, the findings, the flight covered, any oxygen or seating requirement and the GMC registration are on every letter, which is why our letters are accepted at check-in rather than questioned at the gate. A person who does not need a letter is told so and is not charged for one.
Where breathing is the question, the hypoxic challenge test is arranged at a specialist lung function unit and the letter carries the oxygen requirement the airline needs to book, so a passenger with COPD is cleared with 2 litres a minute arranged rather than turned away at the aircraft door. A pregnant passenger at 30 weeks is seen by video the same day and has the letter within the hour.
We also say no. A pneumothorax not yet confirmed resolved, an unstable heart, a wound that should be seen or a saturation that fails the test is not signed off, and the consultation becomes a plan for getting the passenger safe to fly. Places on the 12-month programmes are limited by the number of people one doctor can hold properly, so they begin with an allocation call.
Book a same-day assessment and the letter is written while you wait or call 020 3951 3429.
Related reading
This page is one spoke of the Private GP in London hub. Visitors who have run out of medication before a flight home are covered in Emergency Prescriptions for Visitors to London, employees who need a certificate for work in Private Fit Note in London, and the wider service for travellers in Private GP for International Patients in London.
Frequently asked questions
Do I need a fit to fly letter
Only for pregnancy from 28 weeks, recent surgery, a plaster cast fitted within 48 hours, a heart attack, stroke, pneumothorax or chest infection in recent weeks, a need for oxygen on board, or a condition that has changed since booking. Stable long-term conditions do not need one. At The Wellness a same-day video consultation from £150 tells you which applies before anything is charged.
How much does a fit to fly letter cost in London
A respiratory consultant first appointment costs £250 to £500 before any letter, a Harley Street GP consultation £250 to £350, and a hospital hypoxic challenge test carries its own fee. At The Wellness the assessment is from £150 by video or £220 in person, the letter is from £150 and is written the same day, and the hypoxic challenge test is arranged at a specialist unit where needed.
Can I get a fit to fly letter by video
For pregnancy, medication confirmation and most stable conditions, yes, and the letter follows within the hour. A chest infection, a surgical wound or breathlessness needs to be examined in person, and a saturation below 95% needs a hypoxic challenge test first. At The Wellness video is from £150 and in person from £220.
How late in pregnancy can I fly
Until 37 weeks in an uncomplicated single pregnancy and 32 weeks with twins under Royal College of Obstetricians and Gynaecologists guidance, though most airlines require a letter from 28 weeks confirming the due date and the absence of complications. At The Wellness the letter is issued after a video or in-person assessment from £150.
What is a hypoxic challenge test
A 20-minute test in a lung function unit breathing 15% oxygen, the level in an aircraft cabin, while saturation is measured, to decide whether a person with lung or heart disease can fly without oxygen, needs oxygen on board or should not fly yet. At The Wellness it is arranged at a specialist unit after an assessment from £220 and the letter is written when the result is back.
Will the airline accept a private fit to fly letter
Yes, if it states the diagnosis, the date of assessment, the findings, the flight covered, any oxygen requirement and the doctor's GMC registration, and is signed on the day you were seen. Letters from online forms without an examination are the ones refused. At The Wellness every letter follows an assessment and carries all of the above, from £150.
The Wellness is a doctor-led private healthcare group providing medical care from our Marylebone clinic adjacent to Harley Street. All doctors are GMC-registered. Lung function testing is arranged at specialist units and blood analysis is performed by accredited laboratories. Chest pain, sudden breathlessness or a swollen painful calf before or after a flight need emergency care, not a letter. In an emergency call 999. This article is general information and not a substitute for medical advice about your own health.
Send us your question about flying with a medical condition or email team@thewellnesslondon.com or call 020 3951 3429.
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