Minnesota Flyer - Serving Midwest Aviation Since 1960

By James D. Latkin PhD MD
FACP, CFI,CFII, MEI, Airline Transport Pilot 

Flying by Ear

 


Communication is critical when flying, especially IFR. I was reminded of that a few years ago when we were in the clag, out of Atlanta, Minnesota bound. George was doing most of the flying and things were pretty calm until Atlanta Center issued the somewhat mush-mouthed call: “Two Nyna Fav Delta Lima, fla daarek sea two.” At least that’s what I thought I heard. After a couple of back and forth’s with our heavily accented controller, it was finally discovered that we should fly direct to the Chattanooga, Tennessee VOR known as Choo Choo (GQO). For those of you under the age of eighty, “Chattanooga Choo Choo” was a song written in 1941 and popularized by Glenn Miller’s band during World War II.

I pride myself on being a fairly decent IFR pilot. Not having the foggiest idea where ATC wants me to go is pretty terrifying, even if the confusion only lasts for a few minutes. Since we GA pilots rarely have the benefit of Data Link Communications, we are completely dependent on verbal communication with the controllers. Thus hearing acuity is vital. So let’s talk about hearing; how you might lose it and what to do about it.

There are two general categories of hearing loss, Conductive and Sensorineural.

You might recall from your biology course that sound is collected by the outer ear and funneled to the ear drum (tympanic membrane). The ear drum vibrates from the sound. These vibrations are transmitted through the middle ear to the hearing (acoustic) nerve by tiny bones in the middle ear. Anything that screws up the movement of sound from the outer ear to the inner ear is a conductive hearing loss. A lot of things can cause it. Something as simple as ear wax impaction which is easily corrected by your doctor. Short term loss of hearing can be caused by a cold or allergies that block drainage of the middle ear into the back of the nose. That’s why, if you fly with a stuffed up nose, you start to feel pain in your ear when descending from cruise. Sensorineural deafness happens when the acoustic nerve in the inner ear is damaged. The most common sensorineural hearing loss is associated with long term exposure to loud noise. So, if you’ve been around aircraft for years and years, you can bet on being a little deaf by your fifties or sixties. The acoustic nerve can also be damaged by loud noise or sudden pressure changes as well as infections, head trauma, tumors or diseases of the nervous system.

So, what do you do if you think you’re having trouble hearing? A visit to your personal physician or an ear nose and throat (ENT) specialist should determine if you have significant hearing impairment and what might be causing it. They may well send you to an audiologist for more in-depth hearing tests. This can be particularly important when you have trouble discriminating sounds, especially in a noisy environment. After all, you do want to be able to be sure the controller said “Choo Choo” not “Screw You.” Treatment will of course depend on what’s causing the problem.

Finally, what does the FAA require for hearing acuity? For pilots, you just have to pass the Conversational Voice Test: “For all classes of certification, the applicant must demonstrate hearing of an average conversational voice in a quiet room, using both ears, at six feet, with the back turned to the Examiner.” If you’re deaf in one ear but still pass the Conversational Voice Test, that’s OK with the FAA. If need be, you can use hearing aids. If you do however, your medical certificate will have the restriction “VALID ONLY WITH USE OF HEARING AMPLIFICATION.” You can use your headset for the required hearing amplification if you prefer not to use hearing aids in flight. If you’re completely deaf in both ears your application will have to be deferred to the FAA’s Aerospace Medical Certification Division (AMCD). When you are ready for a check ride, you will contact the AMCD or the Regional Flight Surgeon to arrange a Medical Flight Test (MFT). This test will be given by an FAA inspector in conjunction with the check ride. If you successfully complete the test, the FAA will issue a third-class medical certificate and so-called Statement of Demonstrated Ability (SODA). However, your flying will be restricted to air space in which radio communication is not required.

Fly wisely. See you next month.

As always, comments, questions and suggestions are welcome: jdlakin@mnallergyclinic.com

 

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