Flyin' the ointment.

An aviation medicine 'Dear Doctor'.
Dr. Dougal Watson.



From the September 1995 issue of the AOPA (Australia) magazine.


This is the first Flyin' the ointment column where AOPA member's aviation medical questions are answered. This months column considers a disorder that causes slow paralysis of the lower body, the testing of pilot's hearing, kidney disease and the frequency of aviation medical examinations, and high blood pressure in a prospective student pilot.

The opinions expressed are those of the author and are based on limited medical information. These opinions are no substitute for the considered advice of your Designated Aviation Medical Examiner (DAME) who has a much more in-depth understanding of your medical condition and your individual circumstances.

The opinions expressed should not be construed as reflecting the policy of AOPA, the Civil Aviation Safety Authority (CASA) of Australia, the Royal Australian Air Force, Bureau of Air Safety Investigation, or any other organization or department.

Members are invited to address their aviation medical questions to Flyin' the ointment, c/o The Editor: AOPA Magazine, PO Box 1065, Fyshwick, ACT, 2609. The Editor will forward your letters to Dr. Watson. Some form of contact details, including a phone number, would be desirable in your letter so Dr. Watson can contact you for any further details. No member identification details will be published in the AOPA magazine.


PROGRESSIVE PARALYSIS OF LOWER BODY.

A member writes:

Recently I was diagnosed with having a progressive nerve degenerating disease which so far is only having an effect on the muscles in my legs and lower back. I find I have some difficulty climbing into a Cessna 172 but once in there have no problems operating the controls.

My problem is that the disease is expected to slowly get worse (however there appears to be no time scale to this) and my medical certificate is due to expire. Do you think there is any way I would be able to pass a new medical and if so what type of limitations could I expect to see?

My present age is 48 and other than the above problem I am in very good health and enjoy my flying when I get the opportunity to do so.

Any advice that you could give me on this matter would be greatly appreciated.


A variety of diseases cause this type of slowly progressive, sometimes unpredictable paralysis. Sometimes it is only the muscles and strength that are affected and sometimes the sensory nerves are also damaged.

Such a disorder needn't necessarily stop you from being a fully functioning member of the aviation community. If there are no complicating factors of your disease the final test will be whether, or not, you can safely and competently fly an aeroplane. You can probably expect CASA to insist on a flight test with one of their examiners. If you are able to pass this test you can, quite reasonably, expect that your licence will not be withdrawn.

CASA may want to keep a closer-than-usual eye on the progression of your disorder, they may ask for annual medical examinations. If there are limitations in your flying performance they may restrict the aircraft types you can fly, the types of operations you can undertake, or insist on a copilot or aircraft control modifications.

There are currently several paraplegics (paralysis of the legs and lower body) and quadriplegics (paralysis of arms and legs) licensed to fly in Australia. One of the paraplegics holds a CPL with a twin engine endorsement (I believe there is a modification required of the aircraft controls to allow safe flight during asymmetric flight).

One day your disorder may preclude you from flying but, from your description, this doesn't seem likely at the moment.

In conclusion: Advice:

SUITABILITY OF HEARING TESTS.

A member writes:

I question the suitability of the second stage of audio examination consisting of 100 plus decibels garble with nonsensical words and phrases hardly applicable these days with modern radios and efficient headsets e.g. "Clark" etc., surely standard radio-telephony phrases should be used in the tape.

In the current aircraft types available today where does any pilot have to suffer such noise as produced in that tape?

I must admit when I started flying in service type aircraft in WWII such conditions existed. But not today.

Your letter raises several interesting, and relevant, matters.

The ability to hear voice communication is an integral aspect of aviation today. To hold a pilots licence a certain minimum hearing capacity is required, enough to safely and competently pilot an aircraft. CASA gives pilots three opportunities to demonstrate that their hearing is adequate to the task.

The first opportunity is the standard hearing test which is conducted in a very quiet booth using simple sounds ('beeps' or 'pips') of different volume and tone. If a pilot fails this test a 'speech test' is conducted. The speech test involves words or phrases against a background noise - this is probably the test you're referring to. The speech test is, generally, much easier to pass than the standard hearing test. If a pilot fails the speech test a flight test will probably be required. This is the final arbiter of whether the pilot is able to safely and competently fly the aircraft.

It's pretty easy to understand why the tests are done in this order. The standard test is quick, easy, and cheap and the vast majority of pilots pass it. The few that can't pass the standard test are given a further chance to demonstrate adequate hearing using the slightly more involved speech test. Those that can't pass the speech test are given a further chance during the flight test - the most expensive option but a very reasonable 'final' test.

There are some potential disadvantages of the use of 'aviation phrases' in a speech test. If only aviation phrases or words are used it is possible that the subjects true hearing won't be tested, the test will only demonstrate their capability to recognise a limited set of words and phrases. This would be fine if we could guarantee that exactly the same words are used, in exactly the same order, at all times in aviation. Unfortunately this is not the case, even the most experienced controllers occasionally depart from the standard patter.

It was my understanding that CASA was having 'aviation words' included in their speech test. I'm not sure how far this plan has gone although it would surprise me if they used only aviation words in the test - it might not be a true test of hearing if they did.

If a pilot is required to undertake a flight test to check hearing they can also expect to be tested with non-standard phrases as well as standard patter.

Modern aircraft, although quieter than their WWII counterparts, are not as quiet as they could be. My hearing is unimpaired and I sometimes have difficulty understanding communications when I fly a C150A with handmike and overhead speaker.

While the noise levels in today's GA aircraft are generally much less than aircraft of the WWII era they are not trivial. Take the ubiquitous Cessna 172 for example. A C172 (in good condition) cruising at 100kias at 4000' has a cockpit noise level of approximately 90.3 dB(A), certainly loud enough to cause hearing damage with prolonged exposure. A poorly maintained C172 with a chipped prop, old, worn engine, and poorly fitting panels might be significantly noisier.

I am very wary of the noise levels in modern aircraft and usually wear soft foam insert earplugs as well as a good quality aviation headset when I fly. Even in the above mentioned C150A I try and wear a headset, although it's sometimes impractical during my clumsy attempts at aerobatics.

In conclusion: Advice:

KIDNEY DISEASE AND ANNUAL MEDICAL EXAMINATIONS.

A member writes:

For the last thirty years I have been suffering from IgA nephritis and have been under the care of a Nephrologist. My kidney function is now approx. 25% and I am on medication which is controlling the symptoms well. My blood pressure on the 9th August was 120/80. I am 55 years old and at my last medical the CAA only allowed me to renew my certificate for one year instead of the usual two year period.

I would like to appeal this ruling as I have complete and detailed checkups every two months. I would be agreeable to supply regular details of these to the Director Aviation medicine if this would save having to spend another $100 on a medical in December 1995 which does not seem to me to be as detailed as the ones already carried on a regular basis.

Do you consider this to be a reasonable proposition to put to CAA? If so would AOPA assist me in this matter?

Your questions are more political than medical but I'll try my best.

You do have a significant kidney disease which has caused a considerable reduction in the performance of your kidneys. The problems associated with this kidney disease appear to be well controlled.

It is not unreasonable for CASA to want to keep a close eye on your medical condition. The easiest way they have to do this is by requiring annual aviation medical examinations. Annual aviation medical examinations will provide CASA with the information they want but you might, quite reasonably, question the cost / benefit aspects of this decision.

As I see it you have several options: These options are listed in the order I see as most appropriate. Your DAME might be very amenable to your approach and provide a discount for your medicals. Failing that, CASA may modify their requirement after appropriate representation from you. If that fails you will need to decide between finding the extra funds and requesting further AOPA support in lobbying CASA.

In conclusion: Advice:

HIGH BLOOD PRESSURE AND STUDENT PILOT MEDICAL.

A member writes (via e-mail):

I hope you can help! I am about to embark on the task of procuring a PPL, from scratch.

Can you tell me if having high blood pressure (adequately controlled by medication) will stop me from passing the medical for flying lessons?

Unless your blood pressure is extremely high, or you have side effects from the medications, your blood pressure is not likely to stop you from passing your pilot medical examinations.

The Office of Aviation Medicine at CASA will want to keep an eye on your blood pressure, and other factors, over time to make themselves happy that you aren't at too high a risk of having a heart attack while flying.

Advice:
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