Tag Archives: aeromedical

The Flight Instructor Who Gave Selflessly

Guest Post: By Stephen Hopson

Today I was going to write about the success of the “Flight to Hartford” project with my church (you can find it listed under my name) and tie it into the universal laws of attraction and giving. But something else came up, taking priority.

I just learned that a man who helped me make my dreams of becoming a pilot seven years ago recently passed away. While I understand most of you didn’t know him, I want to share the story of how we met and the incredible impact he had on my life. I believe and hope you’ll be touched even if you’re not a pilot yourself.

We could all learn how to give selflessly like he did. I don’t know whether or not he was aware of the universal laws of attraction and giving but he was sure a good model for someone who did.

Here’s the story.

Right around the turn of the 21st century, I was still in the process of building my speaking and writing career so I was looking for a part-time job to pay the bills in between professional speaking engagements.

It was also at this time when I was already a month or two into flight training but my original instructor was offered a new job in Colorado so I was forced to find a replacement elsewhere.

One day, I had an inspiration to visit other airports to see if I could get a job at a place where they taught people how to fly. I thought, “Why not? Might as well shoot two birds with one stone.”

After visiting one or two and being told nothing was available, I decided to venture a little further out and try Oakland Troy airport, a 30 minute drive from my home.

It was nestled among a fast growing metropolitan area (Troy, Michigan, USA) complete with a new strip mall, new apartments, a giant Wal-Mart and an assortment of other industrial buildings. The only area with open space was a small golf course nearby. The airport was big enough to accommodate corporate jets yet small enough not to require an air traffic control tower.

Pulling onto the newly repaved airport parking lot, I noticed a small circular white terminal building up ahead.

“That must be where I can find the personnel department,” I thought.

Upon setting foot inside, I was surprised to see only a couple of people milling about, drinking coffee and reading the paper. A jovial looking man with rosy cheeks was pouring himself a steaming hot cup of coffee.

Seeing that I was a new face in the place, he set his coffee down and came barreling toward me at 800 mph with an outstretched hand. It startled the heck out of me.

After regaining my composure, I made the mistake of accepting his bone-crushing handshake, causing me to wince in pain.

Trying to hide my pained expression, I said, “Hi, my name is Stephen Hopson and I’m looking for the personnel department.”

“And I’m Don Solms,” he boomed. He was still pumping my now lifeless hand.

Finally releasing his grip, he said, “Oh, you want a job here?” His face brightened even more, if that were possible.

“Yes, do you know of any openings?” I was massaging my fatally injured hand, opening and closing it repeatedly.

“I think they might be looking for someone. HEY, let me take you over to the other building to Susan’s office. She’s the personnel director. COME ON!”

Just before going in her office, Don thrust his business card in my hand and said cheerfully, “Good luck. Shoot me an email later. You’ll have to come over to my hangar where I keep my plane. Okay?”

Keeping both hands within the safety confines of my pockets, I said, “Thanks Don.” I could tell he wanted another hand shake. Fat chance buddy!

Susan then introduced me to two guys named Carl Barnes and Jason Zimmerman. They were both young men who were in charge running flight services. The interview went well and I ended up being hired. As a line service rep, I would be responsible for fueling and towing airplanes, among other things. It marked the beginning of an incredible 4 years at that airport.

One day, Don was hanging out at his hangar where he kept his prized Skylane. It was sunny and breezy. His hangar door was wide open, allowing cool air to swirl around inside. It was an open invitation to anyone who happened to come by. Spotting me in the fuel truck (I was motoring my way back to the terminal after fueling a customer’s plane), he waved me in and offered me a cold soda.

Ten minutes into the conversation, my dreams of becoming a pilot somehow surfaced. I told him that I was actually looking for a new instructor and was trying to save up some money to resume flight training.

Before he could respond, my vibrating pager distracted me with a new text message. There was another fuel order and I had to get going.

“Don, I’ve gotta go – they are telling me to fuel another airplane. See ya later!”

As I got up to leave, he grabbed my arm and gave it a powerful squeeze. My mind did a quick flashback to that day in the terminal. This time his eyes were sparkling like stars. And he was grinning stupidly.

I was in no way prepared for what he was about to say next.

“I would be honored to be your flight instructor and I won’t charge you for my time. All you’d be responsible for is the cost of renting an airplane.”

My God, an angel was in my midst and I knew it.

Absentmindedly rubbing my arms to stem the tide of goose bumps that was spreading like wildfire all over my body, I said, “Wow, really? Thanks man!”

Then he turned serious for a moment and said, “When are you free for your first lesson?”

Thrown off balance since I didn’t expect it to happen so soon, I said, “Well, how about tomorrow?”

“Okay, you got it! ” he thundered. Then he winked as if he were saying, “our secret.”

The rest was history. He was true to his word. Months of flight training with this man proved to be quite an adventure.

He was best known as a jokester, even in the cockpit. Now you have to picture this in your mind. There we were, me, a deaf student pilot and him, a 250 pound flight instructor with a large football frame who liked to poke his elbow at me every time he made a joke. And get this…he thought everything he said was funny!

Ouch!

Aside from his wry sense humor, he was one of the most patient flight instructors I would ever have. Every time we got ready for a lesson, he’d explain in the classroom what we were going to do and then we’d go up and fly.

If he wanted to explain something while we were flying, he’d take control of the airplane while I read his lips and then we’d resume the lesson. Don was one of those rare flight instructors who did not care about building flight time for a future career with the airlines. He was in it for the long haul. In fact, it wasn’t until after 50 plus years of flying and instructing that he finally hung up his wings last year.

He truly enjoyed the fine art of teaching and it showed. He never yelled at his students like some flight instructors who think they are drill sergeants with big egos. His students were his prized possessions and he treated all of them with the respect they deserved.

On December 3, 2000 Don had one big surprise up his sleeve. It was a calm, sunny day. We were scheduled to do some practice takeoffs and landings. After doing three of them, he instructed me to taxi over to the ramp by the white terminal building where I first met him months earlier.

Trying to hide his delight, he said, “Let me see your logbook for a sec.”

Arching my right arm as far back as I could behind the front seats, I snatched the logbook out of my bulging black flight bag and gave it to him.

Suddenly it dawned on me that today was “the day.” He was going to sign me off for my first solo flight!

I felt an involuntary shudder.

After scribbling his signature, he turned and looked at me. His brown eyes were sparkling again. The smile was even bigger than before. He was absolutely giddy, like a child on Christmas morning.

“So Mr. Hopson, are you ready?” he thundered.

“Yes, Don, get the hell out!” I thundered back, half joking.

Roaring like a lion, Don heaved his 250 pound football frame out of the airplane, closed and locked the door with a loud click. Then he did something that forever burned in my mind.

Like a five-star general sending his young fighter pilots off to war, he gave me a smart salute!

I almost burst to tears. It was deeply touching. No one ever did that to me before. Despite being more than ready to solo, I still felt a touch of trepidation so I returned the favor with a slightly shaky hand. Thank God he was too far away to see that.

Taxiing into position on the runway, I took a deep breath and firewalled the throttle causing the airplane to literally leap into the air. I remember thinking, “so this is what everyone means when they say the plane will bounce into the air without your instructor!”

Within seconds after takeoff, all the training kicked in and it was just another exercise around the airport pattern. The only difference was…well, I was alone.

After three takeoffs and landings, the venerable flight instructor waved me over and gave the signal to cut the engine. He stood there like a proud papa and motioned for me to go over to where he was standing. Instead of shaking my hand, he wrapped his huge arms around me and gave me a bone crushing hug. But, hey, I didn’t mind.

Five months later, one day short of my birthday, he finally signed me off to take my pilot certification flight test (i.e. “checkride”) with Mary Carpenter, one of the toughest but fairest FAA examiners from the area. He and Terry Ryan (his airplane co-owner at the time), both accompanied me on the flight to Pontiac airport, a mere 10 minutes away where the examiner’s office was located. He wanted to be there when Mrs. Carpenter and I were done with the checkride.

Two hours later, the examiner walked briskly into the waiting area, smiled and said, “Congratulations, Stephen passed with flying colors!”

Don roared his approval.

We all went out to have our pictures taken by the airplane and that’s when he said to me, “I’ll sit in the back seat on the return flight. Congratulations Mr. Pilot in Command!”

It was the greatest, grandest gesture another human being could ever have bestowed upon me. I’ll never forget it. He was that kind of man. Don believed in me so much that he was literally the only person at that airport who believed I would one day become the world’s first deaf instrument rated pilot.

Six years later, I did it, defying every naysayer in the aviation business. In February 06, I became the world’s first deaf instrument rated pilot. For that I salute Don Solms for believing in me.

Here’s to you Don!

Food for thought: Have you considered the power of the law of giving and helped make someone else’s dream come true this week?

Profoundly deaf since birth, Stephen Hopson is a former award-winning stockbroker turned motivational speaker, author and pilot. He works with organizations that are ready to explore and overcome adversity because no one is immune from it – adversity does not discriminate. His professional speaking services, Obstacle Illusions, include fun and passionate presentations, especially the story of how his fifth grade teacher forever changed his young life with THAT’S RIGHT STEPHEN!

You can view his newly re-designed website at http://www.sjhopson.com.

Stephen also maintains a blog called “Adversity University

How to protect your Hearing in Aviation industry

  • Limiting duration of exposure to noise. OSHA established permissible noise exposure limits for the workplace (including the cockpit of an aircraft).
  • Use Hearing Protection Equipment. If the ambient noise level exceeds OSHA’s permissible noise exposure limits, you should use hearing protection devices—earplugs, earmuffs, communication headsets, or active noise reduction headsets. Even if an individual already has some level of permanent hearing loss, using hearing protection equipment should prevent further hearing damage. These protection devices attenuate noise waves before they reach the eardrum, and most of them are effective at reducing high-frequency noise levels above 1,000 Hz. It is very important to emphasize that the use of these devices does not interfere with speech communications during flight because they reduce high-frequency background noise, making speech signals clearer and more comprehensible.
  • Earplugs. Insertable-type earplugs offer a very popular, inexpensive, effective, and comfortable approach to provide hearing protection. To be effective, earplugs must be inserted properly to create an air-tight seal in the ear canal. The wax impregnated moldable polyurethane earplugs provide an effective universal fit for all users and provide 30 to 35 dB of noise protection across all frequency bands.
  • Communication headsets. In general, headsets provide the same level of noise attenuation as earmuffs, and are also more easily donned and removed that earplugs, but the microphone can interfere with the donning of an oxygen mask.
  • Active noise reduction headsets. This type of headset uses active noise reduction technology that allows the manipulation of sound and signal waves to reduce noise, improve signal-to-noise ratios, and enhance sound quality. Active noise reduction provides effective protection against low frequency noise. The electronic coupling of a low frequency noise wave with its exact mirror image cancels this noise.
  • Combinations of protection devices. The combination of earplugs with earmuffs or communication headsets is recommended when ambient noise levels are above 115dB. Earplugs, combined with active noise reduction headsets, provide the maximum level of individual hearing protection that can be achieved with current technology.

Types and Effects of Noise exposure in Aviation

In one of my previous articles we talked about the Sound, Hearing and Noise in aviation. You can read that article by clicking here. Let’s talk now about the types and effects of noise.

Types of Noise

Steady: Continuous noise of sudden or gradual onset and long duration (more than 1 second). Examples: aircraft power plant noise, propeller noise, and pressurization system noise. According to the Occupational Safety and Health Administration (OSHA), the maximum permissible continuous exposure level to steady noise in a working environment is 90 dB for 8 hours.

Impulse/blast: Noise pulses of sudden onset and brief duration (less than 1 second) that usually exceed an intensity of 140dB. Examples: firing a handgun, detonating a firecracker, backfiring of a piston engine, high-volume squelching of radio equipment, and a sonic boom caused by breaking the sound barrier. The eardrum may be ruptured by intense levels (140dB) of impulse/blast noise.

EFFECTS OF NOISE EXPOSURE

Physiologic

  • Ear discomfort: May occur during exposure to a 120 dB noise.
  • Ear pain: May occur during exposure to a 130 dB noise.
  • Eardrum rupture: May occur during exposure to a 140 dB) noise.
  • Temporary hearing impairment. Unprotected exposure to loud, steady noise over 90 dB for a short time, even several hours, may cause hearing impairment. This effect is usually temporary and hearing returns to normal within several hours following cessation of the noise exposure.
  • Permanent hearing impairment: Unprotected exposure to loud noise (higher than 90dB) for eight or more hours per day for several years, may cause a permanent hearing loss. Permanent hearing impairment occurs initially in the vicinity of 4,000 Hz (outside the conversational range) and can go unnoticed by the individual for some time. It is also important to remember that hearing sensitivity normally decreases as a function of age at frequencies from 1,000 to 6,000 Hz, beginning around age 30.

Psychological

  • Subjective effects: Annoying high-intensity noise can cause distraction, fatigue, irritability, startle responses, sudden awakening and poor sleep quality, loss of appetite, headache, vertigo, nausea, and impair concentration and memory.
  • Speech interference: Loud noise can interfere with or mask normal speech, making it difficult to understand.
  • Performance: Noise is a distraction and can increase the number of errors in any given task. Tasks that require vigilance, concentration, calculations, and making judgments about time can be adversely affected by exposure to loud noise higher than 90 dB.

Selecting Sunglasses for Pilots

Pilot Sunglasses – Aviator

A Summary of how to select best Sunglasses for Pilots

Here is the summary of things to keep in mind while selecting the best sunglasses for pilots, and for that matter, just about anyone who wants to protect his or her vision and have the best quality visual perception. There are other articles (listed at the bottom of this post) on this blog which talk about all this in great detail. Maybe you should read all those articles as well to gain maximum knowledge on the subject. 

SUMMARY.

  1. While adding to the mystique of an aviator, sunglasses protect a pilot’s eyes from glare associated with bright sunlight and the harmful effects from exposure to solar radiation.
  2. Lenses for sunglasses that incorporate 100% ultraviolet protection are available in glass, plastic, and polycarbonate materials. Glass and CR-39® plastic lenses have superior optical qualities, while polycarbonate lenses are lighter and more impact-resistant.
  3. The choice of tints for use in the aviation environment should be limited to those that optimize visual performance while minimizing color distortion, such as a neutral gray tint with 15 to 30% light transmittance.
  4. Polarized sunglasses are not recommended because of their possible interaction with displays or other materials in the cockpit environment.
  5. Since sunglasses are an important asset, whether or not refractive correction is required, careful consideration should be used when selecting an appropriate pair for flying.
  6. The technology associated with ophthalmic lenses is continually evolving, with the introduction of new materials, designs, and manufacturing techniques.
  7. Aviators should consult with their eye care practitioner for the most effective alternatives currently available when choosing a new pair of sunglasses.

References

  1. La Comission Interntionale de l’Eclairage (CIE). Figures correspond broadly to the effects of UVR on biological tissue.
  2. World Meteorological Organization. Scientific Assessment of Ozone Depletion: 1994, WMO Global Ozone Research and Monitoring Project – Report No. 37, Geneva, Switzerland: 1995.
  3. Rash CE, Manning SD. For Pilots, Sunglasses are Essential in Vision Protection, Flight Safety Foundation Human Factors & Aviation Medicine, July-August 2002; 49(4): 1-8.
  4. MEDICAL FACTS FOR PILOTS Publication AM-400-05/1 Written by Ronald W. Montgomery, B.S. Van B. Nakagawara, O.D. Prepared by FAA Civil Aerospace Medical Institute Aerospace Medical Education Division AAM-400, P.O. Box 25082 Oklahoma City, OK 73125
Tony Scott – Top Gun – the movie

Aviators’ Sunglasses Lens Material Options

ULTRA-VOILET RAYS

In one of my previous post – Sunglasses for Pilots, we talked about why it is extremely important for a Pilot to be very careful about choosing proper quality and material for the Sunglasses.

The American Optometric Association recommends wearing sunglasses that incorporate 99 – 100% UVA and UVB protection. Fortunately, UVC, the most harmful form of ultraviolet radiation, is absorbed by the atmosphere’s ozone layer before it reaches the Earth’s surface. Some scientists believe, however, that depletion of the ozone layer may allow more ultraviolet to pass through the atmosphere, making 100% ultraviolet protection a wise choice when selecting eyewear.

LENS MATERIAL

Commonly Used Lens Material The three most common lens materials in use today are optical quality “crown” glass, monomer plastic (CR-39®), and polycarbonate plastic (see Table 1). Lenses made from crown glass provide excellent optical properties (as indicated by the high Abbe value). Crown glass is more scratch resistant but heavier and less impact-resistant than plastic. Glass absorbs some ultraviolet light; however, absorption is improved by adding certain chemicals during the manufacturing process or by applying a special coating. Glass retains tints best over time; however, for higher refractive correction, the color may be less uniform, as parts of the lens will be thicker than others (see Figure 2).

Fig 2. Non Uniform Tints CR-39® plastic lenses possess excellent optical qualities, are lighter in weight, and more impact-resistant than glass lenses, but are more easily scratched, even when scratch resistant coatings are applied. CR-39® lenses tint easily and uniformly, even for those requiring a great deal of refractive correction, but do not hold tints as well as glass. CR-39® plastic can be bleached and re-tinted if fading becomes excessive at some point.

High-index materials (i.e., index of refraction —1.60) are available in both glass and plastic for those who require a large degree of refractive correction and/or desire lighter, thinner lenses. High-index materials are not as widely available, require AR coats to improve optical clarity, and a scratch-resistant coating for durability. In addition, most high-index materials do not accept tints as easily and are less shatter resistant than polycarbonate.

In my next article (click here) you can read about other qualities that you should look for in a Pilot’s or an Aviator’s Sunglasses; like coatings, tints, polarization, frames etc.

Hypoxia – Oxygen deprivation

Breathing is one of the most automatic things we do — over 20,000 times a day. Each breath does two things for our body. It expels carbon dioxide when we exhale, and takes in oxygen when we inhale. It’s a delicate balance.

Exercise or stress increases the production of carbon dioxide, so we breathe faster to eliminate it and take in more oxygen at a greater rate. Because of the effects of gravity, the amount of air containing oxygen is greater at sea level.

For example, the pressure at sea level is twice that found at 18,000 feet MSL. Although the percentage of oxygen contained in air at 18,000 feet is identical to that at sea level (a little over 20%), the amount of air our lungs take in with each breath contains half the oxygen found at sea level. Breathing faster or more deeply doesn’t help. In fact, because you’re consciously over-riding a system that is normally automatic, you’ll be compounding the problem by exhaling too much carbon dioxide.

Supplemental Oxygen

The solution is simple, familiar to most pilots, and required by FAR 91.211: supplemental oxygen. This regulation specifies a 30-minute limit before oxygen is required on flights between 12,500 and 14,000 feet MSL, and immediately upon exposure to cabin pressures above 14,000 feet MSL. For best protection, you are encouraged to use supplemental oxygen above 10,000 feet MSL.

At night, because vision is particularly sensitive to diminished oxygen, a prudent rule is to use supplemental oxygen when flying above 6,000 feet MSL. So, when you fly at high altitudes, supplemental oxygen is the only solution. That’s because supplemental oxygen satisfies the twin demands of having enough oxygen to meet your body’s demands and a breathing rate that excretes the right amount of carbon dioxide.

Hypoxia

Unfortunately, our body doesn’t give us reliable signals at the onset of hypoxia — oxygen starvation — unless we have received special training to recognize the symptoms. In fact, it’s quite the contrary. The brain is the first part of the body to reflect a diminished oxygen supply, and the evidence of that is usually a loss of judgment.

Hypoxia tests

Altitude chamber tests, in which high altitude flight conditions are duplicated, have shown that some people in an oxygen deficient environment actually experience a sense of euphoria — a feeling of increased well-being. These subjects can’t write their name intelligibly, or even sort a deck of cards by suits…yet, they think they’re doing just fine! Such is the insidious nature of oxygen deprivation. It sneaks up on the unwary and steals the first line of sensory protection — the sense that something is wrong — dreadfully wrong.

The higher you go

Bear in mind, the progressive reduction of oxygen per breath will continue the higher you go. Flying above a layer of clouds that doesn’t look too high, or flying in the mountains on a clear day — are the very environments that have caused many good “flat-land” pilots to get into trouble.

Symptoms

Everyone’s response to hypoxia varies. Unless, as we’ve stated, you’ve had special training to recognize its symptoms, hypoxia doesn’t give you much warning. It steals up on you, giving your body subtle clues. The order of symptoms varies among individuals: increased breathing rate, headache, lightheadedness, dizziness, tingling or warm sensations, sweating, poor coordination, impaired judgment, tunnel vision, and euphoria. Unless detected early and dealt with, hypoxia can be a real killer.

Caution and safety

So, don’t decide you’ll try to fly over that range of mountains, thinking you’ll turn back if you start to feel badly. You may feel great…until it’s too late! Use supplemental oxygen.

Smoking and altitude

A Western state pilot lived to tell about this one. Cruising at 13,500 feet MSL over mountainous terrain in his light single, he took a deep drag on his cigarette and next remembered being in a screaming dive with just enough altitude left in which to pull out! That deep drag replaced precious oxygen in his brain with carbon monoxide…and he passed out.

Briefly…

  • When you breathe, you inhale oxygen and exhale carbon dioxide.
  • With each normal breath, you inhale about one-half liter of air, 20% of which is oxygen.
  • At 18,000’ MSL, you have half the sea level air pressure; hence, only half the oxygen.
  • Oxygen starvation first affects the brain; judgment is impaired, so you may not know you are in trouble.
  • We all react differently to the effects of hypoxia. Only physiological training can safely “break the code” for you.

Physiological training for pilots

The effects of hypoxia can be safely experienced under professional supervision at the Civil Aeromedical Institute’s altitude chamber in Oklahoma City and at 14 cooperating military installations throughout the U.S. If you would like to attend a one-day physiological training course, ask your FAA Accident Prevention Specialist for AC Form 3150-7. You’ll learn to recognize your symptoms of hypoxia. It could mean the difference between life and death.

Medical Facts for Pilots Publication AM-400-90/2 (Revised May 2004) Prepared by Federal Aviation Administration Civil Aerospace Medical Institute Aerospace Medical Education Division

Pilot Vision

Vision is a pilot’s most important sense to obtain reference information during flight. Most pilots are familiar with the optical aspects of the eye. Before we start flying, we know whether we have normal uncorrected vision, whether we are farsighted or nearsighted, or have other visual problems. Most of us who have prescription lenses—contacts or eyeglasses—have learned to carry an extra set of glasses with us when we fly, just as a backup. But, vision in flight is far more than a lesson in optics. Seeing involves the transmission of light energy (images) from the exterior surface of the cornea to the interior surface of the retina (inside the eye) and the transference of these signals to the brain.

Anatomy of an Eye

  • Light from an object enters the eye through the cornea and then continues through the pupil.
  • The opening (dilation) and closing (constriction) of the pupil is controlled by the iris, which is the colored part of the eye. The function of the pupil is similar to that of the diaphragm of a photographic camera: to control the amount of light.
  • The lens is located behind the pupil and its function is to focus light on the surface of the retina.
  • The retina is the inner layer of the eyeball that contains photosensitive cells called rods and cones. The function of the retina is similar to that of the film in a photographic camera: to record an image.
  • The cones are located in higher concentrations than rods in the central area of the retina known as the macula, that measures about 4.5 mm in diameter. The exact center of the macula has a very small depression called the fovea that contains cones only. The cones are used for day or high-intensity light vision. They are involved with central vision to detect detail, perceive color, and identify far-away objects.
  • The rods are located mainly in the periphery of the retina — an area that is about 10,000 times more sensitive to light than the fovea. Rods are used for low-light intensity or night vision and are involved with peripheral vision to detect position references including objects (fixed and moving) in shades of grey, but cannot be used to detect detail or to perceive color.
  • Light energy (an image) enters the eyes and is transformed by the cones and rods
    into electrical signals that are carried by the optic nerve to the posterior area of the brain (occipital lobes). This part of the brain interprets the electrical signals and creates a mental image of the actual object that was seen by the person.

The Anatomical Blind Spot

The area where the optic nerve connects to the retina in the back of each eye is known as the optic disk. There is a total absence of cones and rods in this area, and, consequently, each eye is completely blind in this spot. Under normal binocular vision conditions this is not a problem, because an object cannot be in the blind spot of both eyes at the same time. On the other hand, where the field of vision of one eye is obstructed by an object (windshield post), a visual target (another aircraft) could fall in the blind spot of the other eye and remain undetected.

The “Night Blind Spot” appears under conditions of low ambient illumination due to the absence of rods in the fovea, and involves an area 5 to 10 degrees wide
in the center of the visual field. Therefore, if an object is viewed directly at night, it may go undetected or it may fade away after initial detection due to the night blind spot.

The Fovea

The fovea is the small depression located in the exact center of the macula that contains a high concentration of cones but no rods, and this is where our vision is most sharp. While the normal field of vision for each eye is about 135 degrees vertically and about 160 degrees horizontally, only the fovea has the ability to perceive and send clear, sharply focused visual images to the brain. This foveal field of vision represents a small conical area of only about 1 degree. To fully appreciate how small a one-degree field is, and to demonstrate foveal field, take a quarter from your pocket and tape it to a flat piece of glass, such as a window. Now back off 4 ½ feet from the mounted quarter and close one eye. The area of your field of view covered by the quarter is a one-degree field, similar to your foveal vision.

Now we know that you can see a lot more than just that one-degree cone. But, do you know how little detail you see outside of that foveal cone? For example, outside of a ten-degree cone, concentric to the foveal one-degree cone, you see only about one-tenth of what you can see within the foveal field. In terms of an oncoming aircraft, if you are capable of seeing an aircraft within your foveal field at 5,000 feet away, with peripheral vision you would detect it at 500 feet. Another example: using foveal vision we can clearly identify an aircraft flying at a distance of 7 miles; however, using peripheral vision (outside the foveal field) we would require a closer distance of .7 of a mile to recognize the same aircraft. That is why when you were learning to fly, your instructor always told you to “put your head on a swivel,” to keep your eyes scanning the wide expanse of space in front of your aircraft.

Types of Vision

  • Photopic Vision. During daytime or high intensity artificial illumination conditions, the eyes rely on central vision (foveal cones) to perceive and interpret sharp images and color of objects.Mesopic Vision. Occurs at dawn, dusk, or under full moonlight levels, and is characterized by decreasing visual acuity and color vision. Under these conditions, a combination of central (foveal cones) and peripheral (rods) vision is required to maintain appropriate visual performance.
  • Scotopic Vision. During nighttime, partial moonlight, or low intensity artificial illumination conditions, central vision (foveal cones) becomes ineffective to maintain visual acuity and color perception. Under these conditions, if you look directly at an object for more than a few seconds, the image of the object fades away completely (night blind spot). Peripheral vision (off-center scanning) provides the only means of seeing very dim objects in the dark.

Factors Affecting Vision

  • The greater the object size, ambient illumination, contrast, viewing time, and atmospheric clarity, the better the visibility of such an object. During the day, objects can be identified easier at a great distance with good detail resolution. At night, the identification range of dim objects is limited and the detail resolution is poor.
  • Surface references or the horizon may become obscured by smoke, fog, smog, haze, dust, ice particles, or other phenomena, although visibility may be above Visual Flight Rule (VFR) minimums. This is especially true at airports located adjacent to large bodies of water or sparsely populated areas where few, if any, surface references are available. Lack of horizon or surface reference is common on over-water flights, at night, and in low-visibility conditions.
  • Excessive ambient illumination, especially from light reflected off the canopy, surfaces inside the aircraft, clouds, water, snow, and desert terrain can produce glare that may cause uncomfortable squinting, eye tearing, and even temporary blindness.
  • Presence of uncorrected refractive eye disorders such as myopia (nearsightedness — impaired focusing of distant objects), hyperopia (farsightedness — impaired focusing of near objects), astigmatism (impaired focusing of objects in different meridians), or presbyopia (age-related impaired focusing of near objects).
  • Self-imposed stresses such as self-medication, alcohol consumption (including hangover effects), tobacco use (including withdrawal), hypoglycemia, and sleep deprivation/fatigue can seriously impair your vision.
  • Inflight exposure to low barometric pressure without the use of supplemental oxygen (above 10,000 ft during the day and above 5,000 ft at night) can result in hypoxia, which impairs visual performance.
  • Other factors that may have an adverse effect on visual performance include: windscreen haze, improper illumination of the cockpit and/or instruments, scratched and/or dirty instrumentation, use of cockpit red lighting, inadequate cockpit environmental control (temperature and humidity), inappropriate sunglasses and/or prescription glasses/contact lenses, and sustained visual workload during flight.

Focusing

The natural ability to focus your eyes is critical to flight safety. It is important to know that normal eyes may require several seconds to refocus when switching views between near (reading charts), intermediate (monitoring instruments), and distant objects (looking for traffic or external visual references).

Fatigue can lead to impaired visual focusing, which causes the eyes to overshoot or undershoot the target, and can also affect a pilot’s ability to quickly change focus between near, intermediate, and distant vision. The most common symptoms of visual fatigue include blurred vision, excessive tearing, “heavy” eyelid sensation, frontal or orbital headaches, and burning, scratchy, or dry eye sensations.

Distance focus, without a specific object to look at, tends to diminish rather quickly. If you fly over water or under hazy conditions with the horizon obscured or
between cloud layers at night, your distance focus relaxes after about 60-80 seconds.

If there is nothing specific on which to focus, your eyes revert to a relaxed intermediate focal distance (10 to 30 ft). This means that you are looking without actually seeing anything, which is dangerous. The answer to this phenomenon is to condition your eyes for distant vision. Focus on the most distant object that you can see, even if it’s just a wing tip. Do this before you begin scanning the sky in front of you. As you scan, make sure you repeat this re-focusing exercise often.

Dark Adaptation or Night Vision Adaptation

Dark adaptation is the process by which the eyes adapt for optimal night visual acuity under conditions of low ambient illumination. The eyes require about 30 to 45 minutes to fully adapt to minimal lighting conditions. The lower the starting level of illumination, the more rapidly complete dark adaptation is achieved. To minimize the time necessary to achieve complete dark adaptation and to maintain it, you should:

  • avoid inhaling carbon monoxide from smoking or exhaust fumes
  • get enough Vitamin A in your diet
  • adjust instrument and cockpit lighting to the lowest level possible
  • avoid prolonged exposure to bright lights use supplemental oxygen when flying at night above 5,000 ft (MSL)

If dark-adapted eyes are exposed to a bright light source (searchlights, landing lights, flares, etc.) for a period in excess of 1 second, night vision is temporarily
impaired. Exposure to aircraft anti-collision lights does not impair night vision adaptation because the intermittent flashes have a very short duration (less than 1 second).

Visual Scanning

Scanning the sky for other aircraft is a very important factor in avoiding midair collisions, and it should cover all areas of the sky visible from the cockpit. Most of us are instinctively alert for potential head-on encounters with another aircraft. Actually, a study of 50 midair collisions revealed that only 8% were head-on. However, 42% were collisions between aircraft heading in the same direction. So, compared with opposite-direction traffic, your chances of having a midair are over 5 times greater with an aircraft you are overtaking or one that is overtaking you. It is necessary for you to develop and practice a technique that allows the efficient scanning of the surrounding airspace and the monitoring of cockpit instrumentation as well. You can accomplish this by performing a series of short, regularly spaced eye movements that bring successive areas of the sky into the central (foveal) visual field. To scan effectively, scan from right to left or left to right. Begin scanning at the top of the visual field in front of you and then move your eyes inward toward the bottom. Use a stop-turn-stop type eye motion. The duration of each stop should be at least 1 second but not longer than 2 to 3 seconds.

To see and identify objects under conditions of low ambient illumination, avoid looking directly at an object for more than 2 to 3 seconds (because it will bleach out). Instead, use the off-center viewing that consists of searching movements of the eyes (10 degrees above, below, or to either side) to locate an object, and small eye movements to keep the object in sight. By switching your eyes from one off-center point to another every 2 to 3 seconds, you will continue to detect the object in the peripheral field of vision. The reason for using off-center viewing has to do with the location of rods in the periphery of the retina for night or low-intensity night vision (peripheral), and their absence in the center of the retina (fovea). Pilots should practice this off-center scanning technique to improve safety during night flights.

A Word about Monocular Vision

A pilot with one eye (monocular), or with effective visual acuity equivalent to monocular (i.e. best corrected distant visual acuity in the poorer eye is no better than 20/200), may be considered for medical certification, any class, through the special issuance procedures of Part 67 (14CFR67.401) if:

  • A 6-month period has elapsed to allow for adaptation to monocularity; during the adaptation period to monovision, an individual may experience hazy vision and occasional loss of balance.
  • A complete evaluation by an eye specialist, as reported on FAA Form 8500-7, Report of Eye Evaluation, reveals no pathology of either eye that could affect the stability of the findings.
  • Uncorrected distant visual acuity in the better eye is 20/200 or better and is corrected to 20/20 or better by lenses of no greater power than ±3.5 diopters spherical equivalent.
  • The applicant passes an FAA medical flight test.

A Word about Contact Lenses

Use of contact lenses has been permitted to satisfy the distant visual acuity requirements for a civil airman medical certificate since 1976. However, monovision
contact lenses, a technique of fitting older patients who require reading glasses with one contact lens for distant vision and the other lens for near vision, ARE NOT ACCEPTABLE for piloting an aircraft.

The use of a contact lens in one eye for distant visual acuity and a lens in the other eye for near visual acuity is not acceptable because this procedure makes the pilot alternate his/her vision; that is, a person uses one eye at a time, suppressing the other, and consequently impairs binocular vision and depth perception. Since this is not a permanent condition for either eye in such persons, there is no adaptation, such as occurs with permanent monocularity. Monovision lenses, therefore, should NOT be used by pilots while flying an aircraft.

The Eyes Have It

As a pilot, you are responsible to make sure your vision is equal to the task of flying—that you have good near, intermediate, and distant visual acuity because:

  • Distant vision is required for VFR operations including take-off, attitude control, navigation, and landing
  • Distant vision is especially important in avoiding midair collisions
  • Near vision is required for checking charts, maps, frequency settings, etc.
  • Near and intermediate vision are required for checking aircraft instruments

Learn about your own visual strengths and weaknesses. Changes in vision may  occur imperceptibly or very rapidly. Periodically self-check your range of visual acuity by trying to see details at near, intermediate, and distant points. If you notice any change in your visual capabilities, bring it to the attention of your Aviation Medical Examiner (AME). And, if you use corrective glasses or contacts, carry an extra pair with you when you fly. Always remember: Vision is a pilot’s most important sense.

KEY POINTS

  • The sharpest distant focus is only within a one-degree cone.
  • Outside of a 10° cone, visual acuity drops 90%.
  • Scan the entire horizon, not just the sky in front of your aircraft.
  • You are 5 times more likely to have a midair collision with an aircraft flying in the same direction than with one flying in the opposite direction.
  • Avoid self-imposed stresses such as self-medication, alcohol consumption, smoking, hypoglycemia, sleep deprivation, and fatigue.
  • Do not use monovision contact lenses while you are flying an aircraft.
  • Use supplemental oxygen during night flights above 5,000 ft MSL.
  • Any pilot can experience visual illusions. Always rely on your instruments to confirm your visual perceptions during flight.

Medical Facts for Pilots Publication: AM-400-98/2 (revised 8/02) Written by: Melchor J. Antuñano, M.D. Prepared by: Federal Aviation Administration Civil Aerospace Medical Institute Aerospace Medical Education Division

Laser Eye Surgery for Pilots

Currently, about 55% of the civilian pilots in the United States must utilize some form of refractive correction to meet the vision requirements for medical certification. While spectacles are the most common choice for aviators, recent studies show a growing number of pilots have opted for refractive surgical procedures, which include laser refractive surgery. The information in this brochure describes the benefits as well as possible pitfalls laser refractive surgery offers to those considering these procedures.

What is Refractive Error?

Refractive error prevents light rays from being brought to a single focus on the retina resulting in reduced visual acuity. To see clearly, refractive errors are most often corrected with ophthalmic lenses (glasses, contact lenses). The three principal types of refractive conditions are myopia, hyperopia, and astigmatism. Another ophthalmic condition that also results in blurred near vision is called presbyopia. Presbyopia is a progressive loss of accommodation (decreased ability to focus at near distance due to physiological changes in the eye’s crystalline lens) that normally occurs around 40 years of age. Bifocals or reading glasses are necessary to correct this condition.

Myopia (nearsightedness, distant objects appear fuzzy) is a condition in which light rays are focused in front of the retina. About 30% of Americans are myopic. Hyperopia (farsightedness, near objects appear fuzzy) is a condition in which light rays are focused behind the retina. An estimated 40% of Americans are hyperopic. However, this number may not be accurate. Young hyperopes (< 40 years), who can compensate for their farsightedness with their ability to accommodate, are often not counted in this number and some studies incorrectly include presbyopes, who also require plus power lenses to see clearly.

Astigmatism is a condition often caused from an irregular curvature of the cornea. As a result, light is not focused to a single image on the retina. Astigmatism can cause blurred vision at any distance and may occur in addition to myopic or hyperopic conditions. Approximately 60% of the population has some astigmatism.

What is Laser Refractive Surgery?

In October 1995, the Food and Drug Administration (FDA) approved the use of the excimer laser to perform a refractive procedure called Photorefractive Keratectomy (PRK). PRK improves visual acuity by altering the curvature of the cornea through a series of laser pulses. The laser photoablates (vaporizes) the corneal tissue to a predetermined depth and diameter. PRK can be used to correct myopia, hyperopia, and astigmatism. Reported PRK problems such as postoperative pain, prolonged healing period, increased risk of infection, and glare (halos) at night, has resulted in Laser in situ Keratomileusis (LASIK) becoming the preferred choice for refractive surgery by patients and eye care practitioners. A survey in the United States found that the percentage of refractive surgeons performing PRK had decreased from 26% in 1997 to less than 1% in 2002.

LASIK is performed using two FDA approved devices: the microkeratome and excimer laser. During the LASIK procedure, the microkeratome slices a thin flap from the top of the cornea, leaving it connected by a small hinge of tissue. The corneal flap is folded aside and the excimer laser is used to reshape the underlying corneal stroma. The flap is then returned to its original position.

Is LASIK an Option for Me?

An eye care specialist should thoroughly evaluate your current ocular health and correction requirements to determine whether you are a suitable candidate for refractive surgery. Clinical trials have established the following selection criteria for LASIK.

Selection Criteria:

  • Age 18 years or older
  • Stable refractive error (less than .50 diopters [D] change within the last year) correctable to 20/40 or better
  • Less than – 15.00 D of myopia and up to 6 to 7 D of astigmatism
  • Less than + 6.00 D of hyperopia and less than 6 D of astigmatism
  • No gender restriction, with the exception of pregnancy
  • Pupil size less than or equal to 6 mm (in normal room lighting)
  • Realistic expectations of fi nal results (with a complete understanding of the benefits, as well as the possible risks)

In addition to conforming to the above criteria, it is important that you possess normal ocular health and be free of pre-existing conditions that may contraindicate LASIK.

Contraindications:

  • Collagen vascular disease (corneal ulceration or melting)
  • Ocular disease (dry eye, keratoconus, glaucoma, incipient cataracts, herpes simplex keratitis, corneal edema)
  • Systemic disorders (diabetes, rheumatoid arthritis, lupus, HIV, AIDS)
  • History of side effects from steroids
  • Signs of keratoconus
  • Use of some acne medication (e.g., Accutane and/or Cordarone)

Is LASIK Safe for Pilots?

Aviators considering LASIK should know that in initial FDA trials reporting high success rates (> 90%) and low complication rates (<1%), the criteria for success varied. In most clinical studies, success was defined as 20/40 or better distant uncorrected visual acuity (UCVA) under normal room lighting with high contrast targets, not 20/20 or better UCVA. While the majority of patients do experience dramatic improvement in vision after laser refractive surgery, there is no guarantee that perfect UCVA will be the final outcome.

Even successful procedures may leave many patients with a small amount of residual refractive error that requires an ophthalmic device (eyeglasses or contact lenses) to obtain 20/20 visual acuity. If overcorrection results, patients may need reading glasses. Compared to its predecessor (PRK), LASIK requires higher technical skill by the surgeon because a corneal flap must be created. Although rare, loss of best corrected visual acuity (BCVA) can occur when there are surgical complications such as those summarized below.

Surgical Complications:

  • Decentered or detached corneal flap
  • Decentered ablation zone
  • Button-hole flap (flap cut too thin resulting in a hole)
  • Perforation of the eye

Operation of an aircraft is a visually demanding activity performed in an environment that is not always user friendly. This becomes particularly evident if the choice of vision correction is ill-suited for the task. While the risk of serious vision-threatening complications after having LASIK is low (< 1%), some complications could have a significant impact on visual performance in a cockpit environment.

Relative Risk of Post-Surgical Complications:

Prolonged healing periods:
  • 3 months or more
  • Night glare (halos, starbursts): 1 in 50
  • Under/over-correction: less than 1 in 100
  • Increased intraocular pressure: non significant
  • Corneal haze: 1 in 1,000
  • Corneal scarring: non significant
  • Loss of BCVA: 1 in 100
  • Infection: 1 in 5,000
  • Corneal flap complications (dislocated flap, epithelialin growth): less than 1 in 100

Following LASIK, patients are cautioned to avoid rubbing their eyes and to stay out of swimming pools, hot tubs, or whirlpools for at least a week. Contact sports should be avoided for a minimum of 2 weeks, and many eye surgeons recommend wearing safety eyewear while playing sports. Even after the patient’s vision has stabilized and healing appears complete, the corneal flap may not be completely readhered. There have been reports of corneal flap displacement due to trauma up to 38 months after the procedure.After surgery, patients are cautioned to not wear eye makeup or use lotions and creams around their eyes for a minimum of 2 weeks and to discard all previously used makeup to reduce the risk of infection.

In some instances, LASIK may be an option for patients with higher refractive error than can be safely corrected with PRK or those with conditions that can delay healing (e.g., lupus, rheumatoid arthritis). Since LASIK minimizes the area of the epithelium surgically altered, it reduces some of the risks associated with delayed healing. Additionally, ablation of the underlying stromal tissue results in less corneal haze and the tendency for the cornea to revert back to the original refractive condition during the healing process (refractive regression), which improves predictability. Most patients do not require long-term, postoperative steroid use, decreasing the possibility of steroid-induced complications (cataract, glaucoma).

As with any invasive procedure, there are surgical risks, and the recovery process often varies with each individual. Post-LASIK patients report experiencing mild irritation, sensitivity to bright light, and tearing for a few days after surgery. For most, vision stabilizes within 3 months to near-predicted results, and residual night glare usually diminishes within 6 months. In rare cases, symptoms have lingered longer than a year. Earlier versions of LASIK used a smaller ablation zone which sometimes resulted in glare problems at night.

Ablation zones have an area of transition between treated and untreated corneal tissue. As the pupil dilates and becomes larger than the ablation zone, light (car headlights, streetlights, and traffic signals lights) entering through these transition areas becomes distorted, resulting in aberrations perceived as glare. These patients often complain of difficulties seeing under low-light conditions. Patients that develop postoperative haze during the healing process have complained of glare (halos and starbursts). Furthermore, it has been reported that exposure to ultraviolet radiation or bright sunlight may result in refractive regression and late-onset corneal haze. It is therefore recommended that all refractive surgery patients wear sunglasses with UV protection and to refrain from using tanning beds
for several months after surgery.

For those with larger amounts of refractive correction, the predictability of the resulting refractive correction is less exact. This can lead to under-correction (requiring an additional laser enhancement procedure and/or corrective lenses) or over-correction of the refractive error. In the case of overcorrection, premature presbyopia and the need for reading glasses can result. It has been reported that there can be a slower recovery of BCVA and UCVA with hyperopic LASIK compared with those having myopic LASIK. This is especially true for older patients who may be even less likely to achieve UCVA of 20/20 or better. (Note: Loss of BCVA is reportedly 5 to 15 times more likely with refractive surgery than from the use of extended-wear contact lenses.)

Older patients with presbyopia may opt for monovision LASIK, which corrects the dominant eye for distant vision and the other eye for near vision. The procedure is intended to eliminate the need for a patient to wear corrective lenses for near and distant vision.

Anisometropia (difference in correction between the eyes) induced by monovision may result in decreased binocular vision, contrast sensitivity, and stereo acuity. After an adaptation period, patients are often able to see and function normally. Patients who report blurred vision, difficulty with night driving, and other visual tasks in low-light conditions typically do not adapt to monovision and may require an enhancement on their non-dominant eye so that both eyes are fully
corrected for distant vision. Airmen who seek monovision correction should consult an eye care practitioner to assist them in compliance with standards outlined in the “Guide for Aviation Medical Examiners (see below):

Airmen who opt for monovision LASIK must initially wear correction (i.e., glasses or contact lens) for near vision eye while operating an aircraft. After a 6-month period of adaptation, they may apply for a Statement of Demonstrated Ability (SODA) with a medical flight test. If the airman is successful, the lens requirement is removed from their medical certificate.

Advances in Refractive Surgery

Wavefront LASIK

Eye care specialists have traditionally used standard measurement techniques that identify and correct lower-order aberrations, such as nearsightedness, farsightedness, and astigmatism. However, no two people share the same eye irregularities or have similar refractive needs. Vision is unique and as personal as fingerprints or DNA. Wavefront technology allows eye surgeons to customize the LASIK procedure for each eye, providing the possibility of even better vision.
The FDA approved the first system for general use in October 2002. A laser beam is sent through the eye to the retina and is reflected back through the pupil, measuring the irregularities of the light wave (wavefront) as it emerges from the eye. This process produces a three dimensional map of the eye’s optical system. Measuring the cornea’s imperfections or aberrations in this way allows the refractive surgeon to develop a personalized treatment plan for the patient’s unique vision needs. Correcting the patient’s specific imperfections can result in sharper vision, better contrast sensitivity, and reduces problems associated with higher-order aberrations after surgery
, such as haloes and blurred images. Studies indicate that 90-94% of patients receiving wavefront LASIK achieved visual acuity of 20/20 or better. However, those with thin corneas, high degrees of aberrations, severe dry eyes, or conditions affecting the lens and vitreous fluid inside the eye may not be good candidates for wavefront LASIK.

Other Advances in Refractive Surgery

The eye’s optical system creates a limit as to how wide and deep the laser ablation should be, i.e., the wider the ablation, the deeper the laser must ablate into the cornea, which may result in delayed healing and prolonged visual recovery. The development of new lasers allows the creation of a wider ablation zone while removing the least amount of tissue. Studies have shown that this reduces problems with night vision and other side effects associated with laser refractive surgery.

Laser technology that provides variable optical zone sizes and beam shapes with scanning capabilities allows the eye surgeon greater flexibility in developing a more personalized laser vision procedure. A spot laser may be adjusted so minimal spherical aberrations are produced and a larger optical zone is created. Results from clinical trials indicate that 67% of eyes had UCVA of 20/16 or better and 25% had 20/12.5 or better. Additionally, there was an overall improvement in nighttime visual function and night driving, which is achieved by preserving the optical zone size and better shaping of the ablation profile.

During traditional LASIK, the corneal flap is created with a mechanical microkeratome manipulated by the surgeon’s hand. While this method has worked well over the years, the performance of these devices can be unpredictable and is the source of a majority of surgical complications. These difficulties result in irregularities in thickness between the central and peripheral areas of the flap that can induce postoperative astigmatism.

The IntraLase Femtosecond Laser Keratome, which received FDA approval in December 1999, is the first blade-free technology for creating the corneal flap. The laser keratome beam passes into the cornea at a predetermined depth, producing a precise cut that is reportedly more accurate than the microkeratome. Corneal flaps made with the laser keratome appear to adhere more tightly to the corneal bed at the end of the procedure, which may eliminate problems with
long-term flap displacement. A reported disadvantage to this new technology is that surgical time is increased, leaving the stroma exposed several minutes longer, which has led to reported complaints of photophobia and eye irritation for up to two days after surgery. While it may take longer (4 to 7 days) to recover good vision, the approach appears to be associated with a lower incidence of dry eyes, corneal complications, and enhancement procedures compared with traditional LASIK.

The FAA requires that civil airmen with refractive surgical procedures (e.g., PRK, LASIK) discontinue flying until their eye care specialist has determined that their vision is stable and there are no significant adverse effects or complications. The airman should submit one of two documents to the FAA (a report from their eye care specialist or “Report of Eye Evaluation” [FAA-8500-7]). These reports can be submitted directly to the Aerospace Medical Certification Division
when released from care, or to their Aviation Medical Examiner during their next flight physical. This report should state: “. . . . that the airman meets the visual acuity standards and the report of eye evaluation indicates healing is complete, visual acuity remains stable, and the applicant does not suffer sequela, such as
glare intolerance, halos, rings, impaired night vision, or any other complications. . . .” (Guide for Aviation Medical Examiners, July 2005)

If you are a pilot contemplating refractive surgery, consult an eye care specialist to determine if you are a good candidate for laser refractive surgery. Although the FAA and most major air carriers allow laser refractive surgery, professional aviators should consider how it could affect their occupational and certification status. As with any invasive procedure, there are many variables that can influence the final outcome. You should understand all risks as well as the benefits before electing to have a procedure performed that could compromise your visual performance in the cockpit.

MEDICAL FACTS FOR PILOTS Publication OK-06-148 Written by: Van B. Nakagawara, O.D., F.A.A.O. Kathryn J. Wood, CPOT Ron W. Montgomery, B.S.

Medications and Flying

Does this story sound familiar?

It’s Sunday morning, the last day of a three-day trip. You have four hours of flying ahead of you to get back home, but something about the air conditioner last night has left you with stuffy nose and sinuses this morning. You know from your training and experience that flying with congested upper airways is not a good thing. As it turns out, one of the others on the trip has some new over-the-counter sinus pills that are “guaranteed” to unstop your breathing passages and let you fly without any worries about the congestion. Should you take the medication?

Another scenario

You and your spouse are on the second leg of a five-leg, cross-country flight. While visiting relatives, you stayed up late at the party they threw in your honor, ate too much, and the next morning your stomach feels sort of queasy. Your spouse, a non-pilot, offers you a common motion-sickness pill prescribed by her doctor. Should you take the medication?

Get the facts

Just like any other decision (equipment, weather, etc.) that you must make when you fly, you should know all the facts before you can answer this question. There are several things that you need to know and take into account before you make the go/no-go decision. Add these to your check list:

  • First, consider the underlying condition that you are treating. What will be the consequences if the medication doesn’t work or if it wears off before the flight is over? A good general rule to follow is not to fly if you must depend on the medication to keep the flight safe. In other words, if the untreated condition is one that would prevent safe flying, then you shouldn’t fly until the condition improves — whether you take the medication or not.
  • Second, you must consider your reaction to the medication. There are two broad categories of medication reactions. One is a unique reaction based on an individual’s biological make-up. Most people don’t have such reactions but anyone can, given the right medication. Because of this, you should NEVER fly after taking any medication that you have not taken before. It is not until after you have taken the medication that you will find out whether you have this uncommon and unexpected reaction to the medication.
  • Third, consider the potential for adverse reactions, or side effects — unwanted reactions to medications. This type of reaction is quite common, and the manufacturer of the medication lists these on the label. You MUST carefully read all labeling. If you don’t have access to the label, then don’t fly while using the medication.

Look for such key words such as light-headedness, dizziness, drowsiness, or visual disturbance. If these side effects are listed or if the label contains a warning about operating motor vehicles or machinery, then you should not fly while using the medication. Side effects can occur at any time, so even if you’ve taken the same medication in the past without experiencing side effects, they could still occur the next time. For this reason, you must never fly after taking a medication with any of the above-noted side effects.

If you must take over-the-counter medications,

  • Read and follow the label directions.
  • If the label warns of significant side effects, do not fly after taking the medication until at least two dosing intervals have passed. For example, if the directions say to take the medication every 6 hours, wait until at least 12 hours after the last dose to fly.
  • Remember that you should not fly if the underlying condition that you are treating would make you unsafe if the medication fails to work.
  • Never fly after taking a new medication for the first time.
  • As with alcohol, medications may impair your ability to fly—even though you feel fine.
  • If you have questions about a medication, ask your aviation medical examiner.
  • When in doubt, don’t fly.

Prescription Medications

When your treating physician prescribes a medication for you, be sure to ask about possible side effects and the safety of using the medication while flying. Since most of their patients are not pilots, many physicians don’t think about the special needs of pilots when they prescribe medication. You must also discuss the medical condition that is being treated. You may want to ask your physician to contact your aviation medical examiner to discuss the implications of flying with the medical condition and the medication.

When your pharmacy fills the prescription, let the pharmacist know that you are a pilot. Pharmacists are experts in medication side effects and can often provide advice that supplements the information that your physician gives you. The pharmacist will provide you with written information about your medication. You should treat this just like the label of an over-the-counter medication mentioned above. Read, understand, and follow the information and instructions that are given with the medication. Never hesitate to discuss possible problems with your physician, pharmacist, or aviation medical examiner.

The Bottom Line

What you must remember about medications

Sometimes…

…you will develop a medical condition that is not safe to fly with. Whether you take a medication for the condition or not, you should wait to fly until the condition is either gone or significantly improved.

…you will have an ongoing (chronic) medical condition that your physician has prescribed a medication to treat. You should discuss the medical condition and treatment with your physician, pharmacist, and aviation medical examiner and make your flying decision based on their advice.

…you will have a medical condition that makes you uncomfortable but does not impair your ability to safely fly. If flying is very important, you may take either over-the-counter medications or prescription medications — within the guidelines suggested above.

Flying is important for many reasons. Not one of these reasons, however, is worth risking your life or the lives of those around you. Treat all medications with caution, and you’ll be around to become one of the “old” pilots.

MEDICAL FACTS FOR PILOTS Publication OK05-0005 Written by: Steve Carpenter, MD Prepared by: Federal Aviation Administration Civil Aerospace Medical Institute Aerospace Medical Education Division

Hearing and Noise in Aviation

HEARING

The term hearing describes the process, function, or power of perceiving sound. Hearing is second only to vision as a physiological sensory mechanism to obtain critical information during the operation of an aircraft. The sense of hearing makes it possible to perceive, process, and identify among the myriad of sounds from the surrounding environment.

Anatomy and Physiology of the Auditory System

The auditory system consists of the external ear, ear canal, eardrum, auditory ossicles, cochlea (which resembles a snail shell and is filled with fluid), and the auditory nerve. Ambient sound waves are collected by the external ear, conducted through the ear canal, and cause the eardrum to vibrate.

Eardrum vibration is mechanically transmitted to the ossicles, which, in turn, produce vibration of a flexible window in the cochlea. This vibration causes a pressure wave in the fluid located inside the cochlea, moving thousands of hair-like sensory receptors lining the inner walls of the cochlea. The movement of these receptors resembles the gentle movement of a crop field caused by the wind. The stimulation of these sensors produces an electrical signal that is transmitted to the brain by the auditory nerve. This signal is then processed by the brain and identified as a particular type of sound.

SOUND

The term sound is used to describe the mechanical radiant energy that is transmitted by longitudinal pressure waves in a medium (solid, liquid, or gas). Sound waves are variations in air pressures above and below the ambient pressure. From a more practical point of view, this term describes the sensation perceived by the sense of hearing. All sounds have three distinctive variables: frequency, intensity, and duration.

Frequency. This is the physical property of sound that gives it a pitch. Since sound energy propagates in a wave-form, it can be measured in terms of wave oscillations or wave cycles per second, known as hertz (Hz). Sounds that are audible to the human ear fall in the frequency range of about 20-20,000 Hz, and the highest sensitivity is between 500 and 4,000 Hz. Sounds below 20 Hz and above 20,000 Hz cannot be perceived by the human ear. Normal conversation takes place in the frequency range from 500 to 3,000 Hz.

Intensity. The correlation between sound intensity and loudness. The decibel (dB) is the unit used to measure sound intensity. The range of normal hearing sensitivity of the human ear is between -10 to +25 dB. Sounds below -10dB are generally imperceptible. A pilot who cannot hear a sound unless its intensity is higher than 25 dB (at any frequency) is already experiencing hearing loss.

Duration. Determines the quality of the perception and discrimination of a sound, as well as the potential risk of hearing impairment when exposed to high intensity sounds. The adverse consequences of a short-duration exposure to a loud sound can be as bad as a long-duration exposure to a less intense sound. Therefore, the potential for causing hearing damage is determined not only by the duration of a sound but also by its intensity.

NOISE

The term noise refers to a sound, especially one which lacks agreeable musical quality, is noticeably unpleasant, or is too loud. In other words, noise is any unwanted or annoying sound. Categorizing a sound as noise can be very subjective. For example, loud rock music can be described as an enjoyable sound by some (usually teenagers), and at the same time described as noise by others (usually adults).

Sources of Noise in Aviation.The aviation environment is characterized by multiple sources of noise, both on the ground and in the air.

Exposure of pilots to noise became an issue following the introduction of the first powered aircraft by the Wright Brothers, and has been a prevalent problem ever since.

Noise is produced by aircraft equipment power plants, transmission systems, jet efflux, propellers, rotors, hydraulic and electrical actuators, cabin conditioning and pressurization systems, cockpit advisory and alert systems, communications equipment, etc. Noise can also be caused by the aerodynamic interaction between ambient air (boundary layer) and the surface of the aircraft fuselage, wings, control surfaces, and landing gear. These auditory inputs allow pilots to assess and monitor the operational status of their aircraft. All pilots know the sounds of a normal-functioning aircraft. On the other hand, unexpected sounds or the lack of them, may alert pilots to possible malfunctions, failures, or hazards. Every pilot has experienced a cockpit or cabin environment that was so loud that it was necessary to shout to be heard. These sounds not only make the work environment more stressful but can, over time, cause permanent hearing impairment. However, it is also important to remember that individual exposure to noise is a common occurrence away from the aviation working environment—at home or work, on the road, and in public areas. The effects of pre-flight exposure to noise can adversely affect pilot in-flight performance.