Aviation & Eye Care For Pilots

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.

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 they start flying, they know whether they have normal uncorrected vision, are farsighted or nearsighted, or have other visual problems.

Most of them who have prescription lenses, contacts, or eyeglasses have learned to carry an extra set of glasses with us as a backup when they fly; however, vision in flight is far more than a lesson in optics.

Visual Scanning

The probability of spotting a potential collision threat increases with the time spent looking outside, but certain techniques may be used to increase the effectiveness of the scan time.

Effective scanning is accomplished with a series of short, regularly-spaced eye movements that bring successive areas of the sky into the central visual field.

Each movement should not exceed 10 degrees, and each area should be observed for at least 1 second to enable detection.

Although horizontal eye movements seem preferred by most pilots, each pilot should develop a scanning pattern that is most comfortable and adhere to it to assure optimum scanning.

The human eyes tend to focus somewhere, even in a featureless sky. If there is nothing specific on which to focus, your eyes revert to a relaxed intermediate focal distance (10 to 30 feet). This means that you are looking without actually seeing anything, which is dangerous.

In order to be most effective, the pilot should shift glances and refocus at intervals. Shifting the area of focus, at regular intervals, between the instrument panel and then refocusing outside of the aircraft helps to alleviate this problem.

Here, we will focus on vision tasks and challenges related to flying, several vision-related accidents, and practice pearls for optimizing eye care for pilots.

Information about medical conditions, eye surgeries, medications, and so on, can be found in the Federal Aviation Administration (FAA) Vision Standards Title 14, Part 67 of the Code of Federal Regulations (CFR) and the FAA Guide for Aviation Medical Examiners.

In 2019, there were an estimated 664,565 certificated (they are not referred to as licensed) pilots, including student pilots. The average age was 44.2 years. A pilot must meet established vision criteria to be legal to fly and may have a class 1, 2, or 3 flight medical certificate given by an Aviation Medical Examiner.

Or they may choose a relatively new option called BasicMed, in which the Class 3 medical exam can be provided by a licensed physician. Finally, if the pilot is exercising the limited sport pilot privileges, it is necessary to have only a valid driver’s license, which sets the vision standard.

Eye standards for the Class 3 medical certificate—the least restrictive of the 3 classes—are summarized as follows. The full description can be found in the CFR.

» Distance and near visual acuities of 20/40 or better in each eye separately. If corrective lenses (eyeglasses or contact lenses) are necessary for 20/40 vision, they must be worn.

» Ability to perceive those colors necessary for the safe performance of airman duties.

» No acute or chronic pathological condition of either eye or adnexa that interferes with the proper function of an eye that may reasonably be expected to progress to that degree, or that may reasonably be expected to be aggravated by flying.

Before a flight - A pilot prepares for flight by studying maps and weather information related to the intended time, route, and destination. Aviation charts may be paper or digital, and the latter may be accessed via a computer, smart phone, iPad, etc.

The charts are densely populated with print and details in various sizes and colors. The importance of the information is highlighted by the fact that aviation sectional charts for visual flight rules are published on a 56-day cycle.

Prior to entering the aircraft, the pilot will do a pre- flight safety inspection. This may require looking at areas from unusual postures; for example, the underside of a wing on a low-wing aircraft.

Inside the cockpit, the pilot can be faced with a complex array of instruments, lights, switches, and placards at a variety of distances, including overhead, across the breadth of the panel (dashboard), and on or near the floor.

The instrumentation displays may be digital or analog of various colors and sizes.

Airport environment - There are many signs, lights, and markings on or near runways and taxiways that indicate position and directions for a pilot.

These vary in size, color, and location, and some are even painted on the runway or taxiway surface. Navigating around a large unfamiliar airport can be visually challenging during the day and especially at night.

Runway incursions in which a plane taxis onto an active runway without clearance are a constant aviation problem. A landing or departing aircraft may be traveling more than 100 mph and be unable to make sudden adjustments to avoid a collision.

A related problem is landing on the wrong surface; for example, landing on a taxiway instead of a runway or landing on the wrong runway.

In the air - During flight, the pilot is constantly monitoring the instruments inside the cockpit, navigation charts, and displays.

However, attention is mainly directed outside to identify navigation landmarks, and especially to avoid obstacles in the flight path, such as terrain, tall antennas, and other aircraft.

An exception occurs during instrument flight in which attention is (almost) exclusively devoted to the instrument panel.

The view outside changes with the season, weather, terrain, and time of day. A pilot may also travel hundreds of miles on a typical flight and encounter a variety of conditions along the way within a relatively short period of time.

Fatalities - A leading cause of aviation fatalities is spatial disorientation, including somatogravic illusions caused by loss of visual references. This usually happens when a flight under visual conditions continues into conditions of limited visibility.

This was determined to be a factor in the helicopter crash that killed basketball player Kobe Bryant and others.

Lighting - Bright light levels and glare are predominant features of flight during daylight hours.

Other aircraft are surprisingly difficult to see when flying during the day, even if you know where they are supposedly located. Flight takes place in 3-dimensional space in which other planes may be above or below and descending or climbing in any direction.

Weather - Weather conditions permitting, it is the pilot’s responsibility to maintain vigilance, so as to see and avoid other aircraft. This applies to more than other aircraft and includes terrain, towers, and other obstacles—even wildlife; for example, birds or deer on or near a runway when landing or taking off.

Visual acuity - The visual acuity needed to avoid midair collisions is dynamic as well as static. Airplanes may travel at high speeds and 2 general aviation planes on a head-on collision course may be traveling at 120 mph each, hence closing at 240 mph.

Two jets might close at a net 1000 mph or more. If 1 aircraft was masked even for a second in the blur zone of a progressive addition lens, the result could be fatal. However, most midair collisions are not head-on and generally involve a faster aircraft overtaking one that is slower.

Night vision - At night, there is a loss of many visual ground references important for safe flight. Airplanes flying at night are required to have position lights on the wingtips and a strobe or rotating red beacon.

This makes them somewhat more visible than they are during the day unless they are against a background of city lights. Wingtip position lights are red (left) and green (right), and recognizing the physical relationship between the colors indicates whether an aircraft is approaching or receding.

Night vision may be hampered by inadequate dark adaptation after prolonged light exposure during the day. Therefore, wearing tinted lenses during the day may prove beneficial for night flight.

Altitude - Altitude can adversely affect vision. The retina has a high metabolic demand, and altitude-induced hypoxia can adversely affect retinal function including by reducing color perception in low light levels.

Landing - Near the end of a flight, vision and visual attention may be adversely affected by fatigue and hypoxia. It is arguably the time when good vision is most needed because air traffic density is generally greater near airports.

This is a busy time for the pilot, who must configure the aircraft for landing, watch for other aircraft in the traffic pattern, and watch the instruments and approaching runway to establish the correct descent.

Descent guidance may be provided by instruments in the cockpit and lighting systems on the ground that use a horizontal array of red and white lights that indicate if the aircraft is above or below the ideal angle of approach.

Impaired color vision has been a factor in aviation accidents. See “Vision Issues in Aviation Accidents” for an example.