Well, here's a Kiwi take on the subject of anticoagulants.
The UK CAA seem relatively laid back on the matter. The SA CAA, as might be expected since they seem to prohibit more than they understand, are fairly rabid about the stuff.
Perhaps it's more appropriate say that it's complicatedly variable. Perhaps too, since it is sometimes difficult for flight crew to walk around during flight, a two month short haul and three month long no fly zone following hip replacement or resurface would at least be sensible? What a curiosity!
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DRAFT - CAA MEDICAL INFORMATION SHEET - DRAFT
CAA MIS 023
Rev 1: 05/2014
DO1215573-0
An anticoagulant is something that prevents the blood from clotting, or coagulating.
Anticoagulants can be found in nature1 but are also widely used in medicine. Sometimes
anticoagulants are referred to as blood thinners. People are prescribed anticoagulant
medication in a variety of situations where the clotting of their blood is likely to cause
problems in the heart, the brain, or elsewhere in their body.
While there are many reasons for the medical use of anticoagulant medication the
situations most often seen by the CAA are: Prevention of Deep Vein Thrombosis (DVT)
and / or Pulmonary Embolism in susceptible individuals; Prevention of complications after
heart surgery; and the prevention of embolism and stroke in people with Atrial Fibrillation.
This Medical Information Sheet outlines the CAA’s approach to those medications, mainly
warfarin and dabigatran, in the context of aviation safety.
What do anticoagulants do?
Our blood has a number of mechanisms that cause it to clot in certain circumstances. When
the blood’s clotting systems are working well the formation of a blood clot is something
that is beneficial, such as when you get a cut and the clot helps prevent excessive bleeding.
Some people, however, have abnormalities of their clotting systems and are much more
likely to form clots, resulting in DVTs or clots in the blood stream (emboli) causing
damage to other parts of the body (e.g. the brain). Other people have medical problems that
interfere with their, otherwise normal, clotting systems. Problems with the heart, such as
heart surgery, abnormal (or prosthetic) heart valves, and abnormal heart rhythms are a
relatively common cause of small clots forming while bed rest and cancers can cause larger
DVTs.
Anticoagulant medications are used to interfere with the clotting of the blood and so reduce
the likelihood of large or small blood clot formation. Like so many other medications
anticoagulants can be associated with other risks, most notably an increased likelihood of
bleeding problems. This means that it is often important that anticoagulant treatment be
kept in a fairly tight range. Too much anticoagulant effect and there is the risk of bleeding
problems, and too little effect results in the risk of dangerous blood clot formation.
Oral Anticoagulants: Warfarin
and Dabigatran CAA MIS 023
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CAUTION
This Medical Information Sheet contains general advice concerning the CAA’s regulatory handling
of medical conditions. This sheet is not intended as clinical medical advice and should not
ever be used as the basis of decisions concerning your medical care. You should consult your
medical advisers and discuss your options thoroughly with them before making any decisions
about your medical care.
1. Mosquitoes and leeches, for example, inject anticoagulants to make it easier to consume their prey’s blood.
DRAFT - CAA MEDICAL INFORMATION SHEET - DRAFT
CAA MIS 023
Rev 1: 05/2014
DO1215573-0
Is it ok to fly while taking anticoagulant medication?
Sometimes! All anticoagulants have risks associated with their use, and the underlying medical condition that requires them is generally also of aeromedical significance. Despite those risks there are many situations where anticoagulant use is considered to be adequately safe, for private and professional aviation activities.
In some cases, such as after stenting surgery to the heart, the risks of the underlying condition are the main consideration and a stand-down period is utilised (See MIS 0082). In other cases, such as the treatment of recurrent DVT, a fine balance must be maintained with the anticoagulant effect stable and within the therapeutic range. In still other cases some newer oral anticoagulant drugs help make medical management easier and may not result in an unacceptable overall medical risk.
The difficulty — for aviation personnel, their health care professionals, and regulatory authorities — is that no two cases are identical and so the individual medical circumstances of each applicant / certificate holder must be considered.
Which anticoagulants are ok and not ok?
The aeromedical risks associated with anticoagulant medication can never be considered in isolation. The underlying medical condition, and its risks, must also be considered.
All the same, there are some situations where anticoagulant usage is acceptable for aviation purposes. These include:
Aspirin3 use is usually acceptable. However sometimes aspirin is inadequate for reducing the risk of the underlying medical condition, and sometimes the risk of the condition itself is unacceptably high.
Warfarin use may be acceptable, providing it is stably and reliably within the therapeutic range. Often, however, the risks associated with the underlying medical condition are unacceptable.
Dabigatran use may be acceptable. This is a new oral anticoagulant medication which appears to have a risk profile at least equivalent to warfarin, without the need for such careful monitoring of the therapeutic range.
Other new oral anticoagulant agents. Generally not acceptable, although future trial results may modify that stance.
Heparin. Generally not acceptable. Risk associated with underlying medical condition is also likely to be unacceptable.
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2.
Medical Information Sheets
3. Aspirin does prevent clotting but is technically referred to as an anti-platelet agent rather than an anti-coagulant.
DRAFT - CAA MEDICAL INFORMATION SHEET - DRAFT
CAA MIS 023
Rev 1: 05/2014
DO1215573-0
My doctor wants to start me on an anticoagulant. What should I do?
The decision concerning anticoagulation is one for you to make, in discussion with your health care providers. It is important that you tell your doctor that you’re a pilot or air traffic controller so they can tailor their medical advice to your condition and your aviation activities.
If your doctor needs more information about the aviation implications of your planned anticoagulation then they will be welcome to discuss the matter with your CAA Medical Examiner or the Medical Staff at CAA.
If you have a medical condition that results in your doctor wanting to start you on anticoagulant medication you will need to report that to the CAA, either directly or via your Medical Examiner. Your doctor also has an obligation to advise the CAA (See MIS 002 and 0032).
What will the CAA do?
The CAA’s response to your anticoagulation will depend on the overall medical circumstances of your case. It is likely that suspension / disqualification action will be taken initially. In taking that action the CAA will request further information as your medical management continues.
The main things that the CAA will be looking for are:
- Confirmation that the underlying problem has resolved or is adequately and reliably under control or in remission;
- Confirmation that the anticoagulant usage is, in itself, adequately safe; and
- Confidence that that particular anticoagulant can be relied upon to remain safe.
Once these things have been determined, and assuming everything else is ok, it is likely that a medical certificate will be returned—often subject to ongoing surveillance and monitoring conditions, and sometimes (especially professional pilots) subject to ‘multicrew’ restrictions.
Will I be grounded if I am treated with an anticoagulant medication?
Initially suspension / disqualification is most likely. In the majority of cases, once everything is sorted out, medical certification resumes. In some rare cases either the nature of the underlying condition or the risks associated with the anticoagulation itself preclude further medical certification.
But my doctor says I’m fine.
Unfortunately it is not unusual for a treating medical practitioner to believe their patient is ‘fine’ and ‘doing well’ while a regulatory medical practitioner may not be willing to issue a medical certificate. This does not mean that those two doctors necessarily disagree, although it is possible that they do, but is usually an indication that they are viewing the same information from a different perspective.
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DRAFT - CAA MEDICAL INFORMATION SHEET - DRAFT
CAA MIS 023
Rev 1: 05/2014
DO1215573-0
The treating medical practitioner has a primary responsibility towards the health of their patient, while the regulatory practitioner has public safety as their main responsibility. So somebody’s medical situation may, quite correctly, be seen as being very good by the treating doctor but not (yet) safe enough for certification by the regulatory doctors.
What if I don’t agree with a CAA decision concerning my anticoagulation?
You are always able to seek review of CAA medical certification decisions. For further in-formation on review / appeal options you may wish to consult MIS 005 ‘What Are My Re-view Options?” or the medical section of the CAA website (
Civil Aviation Authority of New Zealand).
Medical Information Sheets can be downloaded from the CAA website at —
Medical Information Sheets
Looking at the law
Civil Aviation Rule Part 67: Medical Standards
Rules 67.103(b)(3) (Class 1), 67.105(b)(3) (Class 2), and 67.107(b)(3) (Class 3) contain the main medical standard that relates directly to medications such as the various anti-coagulants. An earlier rule (67.103(b)(1), 67.105(b)(1), and 67.107(b)(1) respectively) provides a more general requirement that also applies to the use of medications.
Many of the medical standards include a reference to the term “aeromedical signifi-cance” which is expanded further in Rule 67.3(a): “A medical condition is of aeromedi-cal significance if, having regard to any relevant general direction, it interferes or is likely to interfere with the safe exercise of the privileges or the safe performance of the duties to which the relevant medical certificate relates”.
In the class 1 medical standards rule 67.103(b)(3) requires that an applicant not be −
(i) taking any drug, medication, substance, or preparation nor undergoing any treatment; or
(ii) experiencing any side-effect from any drug, medication, substance, preparation or treatment -
That, having regard to any relevant general direction, interferes or is likely to interfere with the safe exercise of the privileges or the safe performance of the duties to which a class 1 medical certificate relates.
The general class 1 provisions, rule 67.103(b)(1), also requires an applicant to −
(1) have no medical condition that is of aeromedical significance.
There are other medical standards, also contained in Rule Part 67, that relate more directly to the underlying condition that necessitates the use of anticoagulants but it is beyond the scope of this document to list all of them.
CAA Medical Help Desk
Tel: +64–4–560 9466 Fax: +64–4–560 9470 Email:
[email protected] web site:
Civil Aviation Authority of New Zealand
CAA Central Medical Unit, P O Box 3555, Wellington 6140, New Zealand
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