General Aviation

NTSB’s investigation hearings of the Jan 15th, 2009 US Airways’ Airbus Flight 1549 bird-strike incident which led to the ditching of the aircraft in Hudson river have generated some potential recommendations – developing an on-aircraft anti-bird technology for rounding-up and wiping-out thousands of Canada Geese. At the hearings, Airbus test pilots supported Captain Sullenberger’s decision; to ditch the aircraft in the river instead of trying to make LaGuardia or Teterboro airports.

Airbus’ fly by wire system was commended for allowing Capt. Sullenberger to maintain the best airspeed for the ditching simply by holding the joystick in full aft position and letting the computers do the the rest; not letting the aircraft stall while he simply maintained the wings level.The hearings also reviewed and made public a rather compelling NTSB video animation with overlay-ed ATC audio and CVR content (textual). A board member’s call for more research into onboard bird-repellant or bird-deterrent technologies is supported by at least one study, conducted by Qantas and Precise Flight, which concluded that aircraft equipped with pulsed landing light system resulted in fewer bird strikes.

2004 Tests conducted by the U.S. Agriculture Department were less definitive; but further research (specifically, into flash frequency and light wavelengths) may be recommended by the NTSB.

NextGen, ADS-B and General Aviation

The other day I wrote about how the JDPO is working hard to design the future of aviation, and how the NextGen is going to address the issues related to the safety, capacity and efficiency of the national airspace system while providing a flexible, expandable platform to accommodate future air traffic growth. You can read my article on NextGen Air Transportation System by clicking here.

JDPO is a group of government bodies, and the industry partners include Lockheed Martin, UPS, and a few other major aviation giants.

What I did not realize was that even General Aviation, and Flight Training institutes like the Embry Riddle (ERAU) are such an active partners in this program. As a matter of fact, after I saw this video I realized that as a matter of fact, this time around, this newer technology was handed over to the general aviation community even before the commercial airlines were able to get their hands on it.

In fiscal year 2006, the FAA approved funding for the implementation of Automatic Dependent Surveillance – Broadcast (ADS-B) at eight sites. ADS-B is surveillance, like radar, but offers more precision and additional services, such as weather and traffic information. ADS-B provides air traffic controllers and pilots with much more accurate information to help keep aircraft safely separated in the sky and on runways.

Here is a link to my previous article on ADS-B.

ADS-B Applications for Aircraft

• Enhanced Visual Acquisition: provides the flight crew with enhanced traffic situational awareness in controlled and uncontrolled airspace/airports.
• Enhanced Visual Approaches: enhances successive approaches for aircraft cleared to maintain visual separation from another aircraft on the approach.
• Final Approach and Runway Occupancy Awareness: reduces the likelihood of flight crew errors associated with runway occupancy and improves the capability of the flight crew to detect ATC errors.
• Airport Surface Situational Awareness – Conflict Detection: reduces the potential for deviations, errors, and collisions through an increase in flight crew situational awareness while operating an aircraft on the airport movement area.

Avionics Technician Careers

The more I am learning about this, the more I worry about that who is going to fix all these avionics when they break down. There is already an extreme shortage of aviation mechanics, and these guys are not even trained to repair avionics! And to be able to repair avionics, one doesn’t even have to be an aircraft or aviation mechanic.

And, from my 20 some years of aviation experience, I know that the avionics technicians are much harder to find nowadays, and they make a lot more money as well. So I started to look around to see who all offer Avionics Training, and I was surprised to find that there are quite a few options out there.

One excellent option is Redstone College in the Denver area. Redstone and Lockheed Martin even have a joint scholarship program for Avionics Training. If I had the choice to go back in time, I know what I would do.

In one of my previous articles we talked about the NextGen; Next Generation Air Transportation System, and how it is working towards making the future of the air navigation in aviation industry better, safer and automated. We have also talked about how the future of aviation is getting more environment friendly and greener. If you have not read those articles, I suggest you read those as well to get the most accurate and complete information on this topic.

One of NextGen’s most promising initiatives with potential for broad operational applications is Automatic Dependent Surveillance-Broadcast (ADS-B), a technology that could revolutionize air navigation and surveillance, and be the backbone of the future system.  In fact, some companies, such as United Parcel Service (UPS), are already using ADS-B in their operations, and are realizing savings in jet fuel and faster delivery schedules.

ADS-B uses GPS satellites and ground-based equipment to allow aircraft to broadcast their transmissions with greater frequency and accuracy than the current land-based legacy radar systems.  With ADS-B, pilots will see exactly what the air traffic controller sees.

The Capstone program is a long-term, highly successful application of ADS-B in a non-radar environment.  ADS-B, one of NextGen’s essential foundational technologies, will continue its development with the goal of deployment throughout Alaska.  Since initial deployment, general aviation accidents have decreased by 40%.  The practical information provided by this FAA program has also proven invaluable in guiding the development of NextGen.

The United Parcel Service (UPS) is using ADS-B in trials at its hub in Louisville, Kentucky. The company is realizing savings while simultaneously reducing the adverse environmental impact of its flight operations.  The traditional “step-down” landing approach requires planes to use high thrust to level off at different stages, resulting in more fuel burn and additional noise and pollution.  ADS-B allows for an improved landing procedure called Optimized Profile Descents.

Taking advantage of improved situational awareness, Optimized Profile Descents permit planes to constantly descend from cruise altitude all the way to touch-down.  Using Optimized Profile Descents, UPS reduced flight time, allowing more planes to land, while cutting back on emissions and noise.  Once ADS-B is fully implemented, UPS anticipates an annual fuel reduction of 800,000 gallons.  Furthermore, the company forecasts a 30% decrease in noise and an emissions reduction of 34% in the vicinity of airports (3,000 feet or below).

The FAA signed a Memorandum of Agreement with helicopter operators, and oil and gas platform owners in the Gulf of Mexico to improve air traffic control in the region.

Currently, most helicopters operating offshore in the Gulf cannot communicate or be seen by air traffic controllers, requiring pilots to rely mostly on visual flight rules.  As a result, helicopter service to offshore platforms is severely curtailed in poor visibility conditions.

With ADS-B equipment installed on aircraft and platforms, helicopters are able to transmit critical position information to the Houston Air Route Traffic Control Center, resulting in improved communications.  This allows for continued helicopter activity on platforms in poor visibility in contrast to periodic weather-related stoppages.

Network-Enabled Operations (NEO) refers to the ability to link together information from a wide range of sources.  It is a high priority for JPDO and NextGen partner agencies.  NEO provides a platform for interested parties to have consistent, up-to-date, secure, and simultaneous access to the same information.

The Future of Aviation

NextGen, shorthand for the Next Generation Air Transportation System, refers to a wide-ranging initiative to transform the air traffic control system. It focuses on leveraging new technologies, such as satellite-based navigation, surveillance, and networking. The initiative involves meaningful collaboration among government departments and agencies as well as companies in the aerospace and related industries.

Currently, the U.S. air transportation system handles roughly 50,000 flights over a 24-hour period. By 2025, air traffic is projected to increase two-to-three fold, equating to 100,000-150,000 flights every 24 hours. It is acknowledged that the current U.S. air transportation system will not be able to meet these air traffic demands.

In transforming the national airspace system, JPDO is working with the FAA , NASA , the Departments of Transportation , Defense , Homeland Security , Commerce , and the White House Office of Science and Technology Policy .

The Senior Policy Committee of JPDO directs the NextGen initiative. The committee is chaired by the Secretary of Transportation, and includes the Undersecretary for Policy of the Department of Transportation; Administrator of the Federal Aviation Administration; Administrator of the National Aeronautics and Space Administration; Secretary of the United States Air Force, representing the Department of Defense; Deputy Secretary of the Department of Commerce; Deputy Secretary of the Department of Homeland Security; and the Director of the White House Office of Science and Technology Policy.

There are nine capabilities that will enable the transformation of the national air transportation system. The NextGen capabilities are as follows:

1. Integrated NextGen Information
2. Separation Management
3. Capacity Management
4. Trajectory Management
5. Security
6. Flow Contingency Management
7. Environment
8. Safety
9. Flexible Airport and Surface Operations

Providing a high level of security in air transportation is a major goal for NextGen, which envisions a layered, adaptive security system.  This means a system that depends on multiple technologies, policies, and procedures that adapt to individual situations, and can change according to the threat level.  Other security measures will be in place as additional roadblocks to neutralize the threat, whether it is in the airport, on the plane, or in the air.

Intercontinental travel is, of course, a key element of the world’s air transportation system.  “Global Harmonization” is the technical term for coordinating NextGen activities with our counterparts throughout the world.

The FAA entered into an agreement with the European Commission (EC), which formalized cooperation between the NextGen initiative and its European counterpart, the Single European Sky Air Traffic Management Research (SESAR) program.  The FAA and EC are following through to identify opportunities and, as appropriate, establish timelines to implement common, interoperable, performance-based air traffic management systems and technologies.

And by the way, the ability to track any flight, whether commercial airline flights, or privately owned Cessna aircraft, from the convenience of your computer is already available, and I have talked about it in my other post – Live Flight Tracking. And it is Free.

ADS-B; Automatic Dependent Surveillance Broadcast is one of the initiatives of the JPDO’s NextGen program. You can read all about it here; and watch the video as well. It is pretty cool!

Whoa! I just bumped into this information accidentally while doing some research on Airparks. Somehow I ended up on Rosamond Airpark’s website, and guess what I found? As just about everything else is migrating online (internet), FAA has already moved the FAA pilot medical certificate application online as well. I had no idea about this. I know the pilot practical test application (form 8710) was made available online a while back, but had no clue that the student pilot certificate and/or pilot medical certificate application can also be completed online at this site: https://medxpress.faa.gov/.

So, you can complete your medical application online, and the FAA Aero-medical examiner (AME) can review the application on his/her computer when you go visit for the medical. Yup. You still have to go see the AME. Maybe in the future there would be ways to save the trip and do the entire thing online. But for now, I think this is great! I am so liking this that I think I am going to go get me another medical anyways, even though I have about 4 more years before I need a renewal.

And yes, we will talk about medical certificate regulations in some other post sometime. I know this would be a good topic for the future.

Aviation has completed over a century of dynamic growth and advancement, resulting in the present air transportation system dominated by the commercial airline industry’s hub and spoke system. The initial 50 years of aviation were a chaotic, rapid evolutionary process involving disruptive technologies that required frequent modifications. The second half century produced a stable evolutionary optimization of services based on achieving an objective function  of economical operations. In the ongoing 50 years of what I call Aviation 3.0, there is a potential for aviation to transform itself into a more robust, scalable, adaptive, secure, safe, affordable, convenient, efficient, and environment friendly system. Read more about environment friendly aviation initiative in my “Green is the future of Aviation as Well” article.

However, such a global optimization requires not only the ability to perform analysis of larger system of system impacts, but also the ability to consider new value propositions that involve different infrastructures and business models that those which are currently the norm of the present aviation industry. While many obstacles exist, including technology, regulations, and perception; the Aviation 3.0 has the potential to mirror other on-demand market revolutions that have taken place over the past half century.

Highly successful innovators like Henry Ford and even Wright brothers believed that aviation would one day be capable of reaching an everyday impact in our daily lives. Yet after many years of rather empty promises, ranging from road-able aircraft to a a helicopter in every garage, the aviation community remains transfixed in a highly centralized world of very expensive, and not cost efficient aircraft.

Pessimists of the personal aircraft vision say that the aviation market evolution has brought us to the logical solution. Optimists of the vision respond that government regulations and the conservatism of the aerospace community have inhibited the industry. Both are correct, and as is typically the case, the answer lies somewhere in the middle. However, with a long-term viewpoint of demand and utility, it seems inevitable that in the very near future small aircraft will have a far more significant daily impact in many of our daily activities.

Sport pilot regulations, training and certification of the pilots, and the sport aircraft are a result of such an initiative from the government and the industry. If you desire to experience the spirit of what I am trying to express here in this article, find some time during your busy lives, visit your local GA airport, and ask someone in one of those FBOs to arrange for a demo flight for you in one of their Sport Aircraft. And then come back here and give this article and second read. And leave me a comment here underneath.

I was reading an article about when do you have to report a DUI or DWI related action (in a motor vehicle) to the Federal Aviation Administration (FAA)? You can read it here. It is true that any arrest, and/or conviction has to be reported to the FAA within 60 days, as required by FAR 61.15 . Some pilots have a misunderstanding that they only need to report the conviction and not the arrest, and, the others think that they have to report only when they go back for their Pilot Medical Certificate renewal. Both these are far from the truth.

Another thing we need to understand is that honesty here is always the best policy. FAA does occasionally check the National Driver Register against pilot, mechanic and other FAA certificate holder names. And if you have failed to report your incident within the applicable time frame, which is 60 days, and FAA comes across your name during it’s driver record search, you will definitely have something much bigger to worry about.

It is common for the FAA to not take any action against the offending pilot on the first instance of a driving DUI/DWI. Subsequent ones, I don’t know. I have not come across such a  pilot or a mechanic yet! If someone out there knows of such a dare-devil, please drop me a comment there with a contact information so I can enhance my knowledge from his/her experiences.

8 hours bottle to throttle is the minimum, as per FAR 91.17 .  That’s right, no matter how small the sip, you stay away from that ramp until at least 8 hours has elapsed. And that’s not all. 04% alcohol concentration in the blood or breath is enough to get you in trouble with the FAA as well. Perhaps it takes less that that .04% concentration for you to be affected. Or have you considered how badly you’re likely to perform while hung over? Quite a few studies have documented the loss of performance, judgment, and reaction time you can anticipate even after your blood alcohol content has dropped back down to acceptable levels.

So, remember, alcohol and aviation, for that matter just about anything physical, , yes that too, is not a good combination and should be avoided at all times. Alcohol is to be consumed and enjoyed very responsibly.

Oh by the way, the ol’ pilot rule of the thumb to remember this (in case you are a forgetful person) is called Whiskey Compass rule. We’ll talk about it some other day.

From prehistoric times, humans have watched the flight of birds, longed to imitate them, but lacked the power to do so. Logic dictated that if the small muscles of birds can lift them into the air and sustain them, then the larger muscles of humans should be able to duplicate the feat. No one knew about the intricate mesh of muscles, sinew, heart, breathing system, and devices not unlike wing flaps, variable-camber and spoilers of the modern airplane that enabled a bird to fly. Still, thousands of years and countless lives were lost in attempts to fly like birds.

The identity of the first “bird-men” who fitted themselves with wings and leapt off a cliff in an effort to fly are lost in time, but each failure gave those who wished to fly questions that needed answering. Where had the wing flappers gone wrong? Philosophers, scientists, and inventors offered solutions, but no one could add wings to the human body and soar like a bird. During the 1500s, Leonardo da Vinci filled pages of his notebooks with sketches of proposed flying machines, but most of his ideas were flawed because he clung to the idea of birdlike wings. Fig 1 By 1655, mathematician, physicist, and inventor Robert Hooke concluded the human body does not possess the strength to power artificial wings. He believed human flight would require some form of artificial propulsion.

The quest for human flight led some practitioners in another direction. In 1783, the first manned hot air balloon, crafted by Joseph and Etienne Montgolfier, flew for 23 minutes. Ten days later, Professor Jacques Charles flew the first gas balloon. A madness for balloon flight captivated the public’s imagination and for a time flying enthusiasts turned their expertise to the promise of lighter-than-air flight. But for all its majesty in the air, the balloon was little more than a billowing heap of cloth capable of no more than a one-way, downwind journey.

Balloons solved the problem of lift, but that was only one of the problems of human flight. The ability to control speed and direction eluded balloonists. The solution to that problem lay in a child’s toy familiar to the East for 2,000 years, but not introduced to the West until the 13th century. The kite, used by the Chinese manned for aerial observation and to test winds for sailing, and unmanned as a signaling device and as a toy, held many of the answers to lifting a heavier-than-air device into the air.

One of the men who believed the study of kites unlocked the secrets of winged flight was Sir George Cayley. Born in England 10 years before the Mongolfier balloon flight, Cayley spent his 84 years seeking to develop a heavier-than-air vehicle supported by kite-shaped wings. Fig 2 The “Father of Aerial Navigation,” Cayley discovered the basic principles on which the modern science of aeronautics is founded, built what is recognized as the first successful flying model, and tested the first full-size man-carrying airplane.

For the half-century after Cayley’s death, countless scientists, flying enthusiasts, and inventors worked toward building a powered flying machine. Men, such as William Samuel Henson, who designed a huge monoplane that was propelled by a steam engine housed inside the fuselage, and Otto Lilienthal, who proved human flight in aircraft heavier than air was practical, worked toward the dream of powered flight. A dream turned into reality by Wilbur and Orville Wright at Kitty Hawk, North Carolina, on December 17, 1903.

The bicycle-building Wright brothers of Dayton, Ohio, had experimented for 4 years with kites, their own homemade wind tunnel, and different engines to power their biplane. One of their great achievements was proving the value of the scientific, rather than build-it-and-see approach to flight. Their biplane, The Flyer, combined inspired design and engineering with superior craftsmanship. Fig 3 By the afternoon of December 17th, the Wright brothers had flown a total of 98 seconds on four flights. The age of flight had arrived.

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

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.