The following are the requirements for the medical certification of aircrew, including guidance material issued by the UK CAA Medical Department in relation to the metabolic and endocrine systems.
MED.B.025 Metabolic and Endocrine Systems
Implementing Rules
- Applicants with metabolic, nutritional or endocrine dysfunction may be assessed as fit subject to demonstrated stability of the medical condition and satisfactory aero-medical evaluation.
- Diabetes mellitus
- Applicants with diabetes mellitus requiring insulin shall be assessed as unfit.
- Applicants with diabetes mellitus not requiring insulin shall be assessed as unfit unless it can be demonstrated that blood sugar control has been achieved and is stable.
- Aero-medical assessment
- Applicants for a class 1 medical certificate requiring medication other than insulin for blood sugar control shall be referred to the medical assessor of the licensing authority.
- The fitness of applicants for a class 2 medical certificate requiring medication other than insulin for blood sugar control shall be assessed in consultation with the medical assessor of the licensing authority.
Acceptable Means of Compliance
CLASS 1 - AMC1 MED.B.025
(a) Metabolic, nutritional or endocrine dysfunction
Applicants with metabolic, nutritional or endocrine dysfunction may be assessed as fit if the condition is asymptomatic, clinically compensated and stable with or without replacement therapy, and regularly reviewed by an appropriate specialist.
CLASS 2 - AMC2 MED.B.025
(a) Metabolic, nutritional or endocrine dysfunction
Applicants with metabolic, nutritional or endocrine dysfunction should be assessed as unfit. A fit assessment may be considered if the condition is asymptomatic, clinically compensated and stable.
CLASS 1 - AMC1 MED.B.025
(b) Obesity
Applicants with a Body Mass Index greater than or equal to 35 may be assessed as fit only if the excess weight is not likely to interfere with the safe exercise of the applicable licence(s) and the results of a risk assessment, including evaluation of the cardiovascular system and evaluation of the possibility of sleep apnoea, are satisfactory.
CLASS 2 - AMC2 MED.B.025
(b) Obesity
Applicants with a Body Mass Index greater than or equal to 35 may be assessed as fit only if the excess weight is not likely to interfere with the safe exercise of the applicable licence(s) and the results of a risk assessment, including evaluation of the cardiovascular system and evaluation of the possibility of sleep apnoea, are satisfactory.
CLASS 1 - AMC1 MED.B.025
(c) Addison’s disease
Applicants with Addison’s disease should be assessed as unfit. A fit assessment with an OML may be considered, provided that cortisone is carried and available for use whilst exercising the privileges of the applicable licence(s).
CLASS 2 - AMC2 MED.B.025
(c) Addison’s disease
Applicants with Addison’s disease may be assessed as fit provided that cortisone is carried and available for use whilst exercising the privileges of the applicable licence(s).
CLASS 1 - AMC1 MED.B.025
(d) Gout
Applicants with acute gout should be assessed as unfit. A fit assessment may be considered once asymptomatic, after cessation of treatment or the condition is stabilised on anti-hyperuricaemic therapy.
CLASS 2 - AMC2 MED.B.025
(d) Gout
Applicants with acute gout should be assessed as unfit until asymptomatic.
CLASS 1 - AMC1 MED.B.025
(e) Thyroid dysfunction
Applicants with hyperthyroidism or hypothyroidism should be assessed as unfit. A fit assessment may be considered when a stable euthyroid state is attained.
CLASS 2 - AMC2 MED.B.025
(e) Thyroid dysfunction
Applicants with thyroid disease may be assessed as fit once a stable euthyroid state is attained
CLASS 1 - AMC1 MED.B.025
(f) Abnormal glucose metabolism
Glycosuria and abnormal blood glucose levels require investigation. A fit assessment may be considered if normal glucose tolerance is demonstrated (low renal threshold) or impaired glucose tolerance without diabetic pathology is fully controlled by diet and regularly reviewed.
CLASS 2 - AMC2 MED.B.025
(f) Abnormal glucose metabolism
Glycosuria and abnormal blood glucose levels require investigation. A fit assessment may be considered if normal glucose tolerance is demonstrated (low renal threshold) or impaired glucose tolerance is fully controlled by diet and regularly reviewed.
CLASS 1 - AMC1 MED.B.025
(g) Diabetes mellitus
Subject to good control of blood sugar with no hypoglycaemic episodes:
(1) applicants with diabetes mellitus not requiring medication may be assessed as fit;
(2) the use of antidiabetic medications that are not likely to cause hypoglycaemia may be acceptable for a fit assessment with an OML
CLASS 2 - AMC2 MED.B.025
(g) Diabetes mellitus
Applicants with diabetes mellitus may be assessed as fit. The use of antidiabetic medications that are not likely to cause hypoglycaemia may be acceptable.
Guidance Material
Benign Pituitary Tumours Class 1 and 2
Applicants with symptoms and/or on first diagnosis should be assessed as unfit.
A fit assessment can be considered subject to a satisfactory endocrinologist’s report and visual fields assessment after 3 months of being stable on treatment.
Annual follow-up with endocrinology report and visual fields is required.
Cabergoline is used for the treatment of microprolactinomas. It is acceptable for any class of certification, providing the pilot has been stabilised on this medication for a period of not less than three months on the ground and has no adverse side-effects from the therapy.
Obesity
Guidance on obesity and treatments is available in the Information sheet for pilots and air traffic controllers and in the section on GLP-1 agonists on this page.
There is also information on the Medical Flight Test - Musculoskeletal.
Aeromedical assessment of applicants prescribed GLP-1 receptor agonists (including combined GIP / GLP-1 receptor agonists) for obesity
GLP-1 receptor agonists given subcutaneously are compatible with all classes of certification (Class 1/2/3/LAPL). Oral formulations are not presently compatible due to the high potential variability in absorption profile.
Available certification: Unrestricted Class 1/2/3/LAPL.
Initiation: Applicants should be made unfit for a period of at least 2 weeks upon starting treatment. A subsequent fit assessment should be made by an aeromedical examiner (AME) which includes confirmation of no side effects that could impair aeromedical fitness (including gastrointestinal upset, dizziness and mental health difficulties).
Dose adjustment: Unfit for at least 72 hours. AME assessment not required for return to flying and/or controlling.
Monitoring: As per obesity follow up requirements in the Information sheet for pilots and air traffic controllers.
Thyroid Dysfunction Class 1 and 2
Download UK CAA Guidance on Thyroid Dysfunction (PDF)
Abnormal Glucose Metabolism Class 1 and 2
Glycosuria should always be investigated with a minimum of random blood sugar. Symptomatic individuals should have an oral glucose tolerance test.
Class 1 applicants with impaired glucose tolerance should be reviewed annually.
Diabetes Guidance Material
The following documents provide information for pilots and air traffic controllers with diabetes:
- Medical certification for pilots and air traffic controllers with diabetes.
- Briefing sheet for certificate holders with diabetes.
- Medical flight test report for pilots treated with potentially hypoglycaemic medication.
- Operational test report for ATCOs treated with potentially hypoglycaemic medication.
- Specification for diabetes reports.
Protocol for insulin treated diabetes
Consistent with the International Civil Aviation Organization’s (ICAO) Standards and Recommended Practices, most countries do not yet permit pilots with insulin treated diabetes to continue flying. The UK Civil Aviation Authority (UK CAA) has been one of the leading aviation authorities in working to enable this.
In 2014, the UK CAA established an assessment protocol for insulin treated diabetes and this enabled us to issue certificates to pilots, with heightened levels of oversight, while gathering data to demonstrate the safety of the system. Ireland and Austria joined the UK in running the protocol and these states continue to work in partnership.
The protocol we are currently following requires that any Class 1 certificate issued is endorsed with an operational multi-pilot limitation (OML), which limits the pilot’s privileges to operating only as or with a qualified co-pilot. In accordance with UK regulation, this endorsement can only be applied where the certificate holder already holds a UK commercial pilot licence as it takes account of skill and experience. We can issue Class 2 medical certificates to those who are or wish to become private pilots, as long as they meet the requirements of the protocol.
Horizon Europe research project
We are also part of a consortium engaged in a Horizon Europe research project that is due to conclude at the end of 2025. As part of this project, insulin pumps and continuous glucose monitoring systems, working individually and as closed loop systems, have been tested both in flight and in pressure chambers that simulate the cabin altitude profiles of flight, including the effects of cabin decompression.
This has been the first research of its kind and the findings are being published in peer reviewed medical journals as they become available. The project is also looking at the risk assessment of applicants and certification processes. We work closely with those aviation authorities around the world who do consider applicants with insulin treated diabetes and we are trying as far as possible to harmonise our requirements. At every stage, passenger safety has been paramount.
Looking forward
As we approach the end of the research project and assuming the results continue to be favourable, it is our intention to update the protocol to include initial Class 1 applicants with well controlled insulin treated diabetes, who do not already hold a commercial pilot’s licence.
We are also looking at how we include Class 3 applicants. We are working with our partners to make these changes in a careful and considered fashion. This is likely to require data accumulated over months to demonstrate exemplary glucose control as well as an assessment of risk factors for associated medical conditions.
In anticipation of an increasing number of applicants with insulin treated diabetes, we will be making changes to our diabetes clinic. As we need to ensure we have sufficient diabetes specialist medical resource, this is unlikely to be possible until mid-2025 at the earliest.
We appreciate that the wait may be difficult for those who are keen to become pilots and ask for your patience and understanding as we complete our evidence gathering and make changes to enable this to happen safely.
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