Did You See What
You Thought You Saw?
Accident investigations sometimes determine the cause of the accident to be “failure to maintain terrain clearance” or “loss of control for undetermined reasons”. The pilot’s apparent mistake could very easily have resulted from not seeing the altitude limit noted on the procedure or misidentifying the bearing to be flown from a fix. One local approach plate I use frequently has the VOR and ILS facilities almost co-located, with frequencies of 110.2 and 110.7, respectively. In dim light, or when working hurriedly at a single-pilot’s pace, you can understand why it’s easy to choose and dial-in the wrong number. If one doesn’t verify the ID code, the lack of a glideslope while tracking inbound can be confusing.
Mistakes made when keying in routings on an FMS, hurriedly typing numbers with the “fat finger syndrome” that plagues many of us, can just as easily be blamed on not clearly seeing the readout. If available, having two sets of eyes to verify that the flight plan is entered correctly is critical; hopefully, one of the pairs will be younger, or better corrected.
And so, it is important to treat vision as the critical component of successful piloting that it is. Very likely, you will need corrective vision aids as your career progresses; it is, to put it in my father’s terms, “part of growing up.” Whether or not your medical certificate calls for “must possess corrective lenses for near vision”, keep some reading glasses handy, to make your job easier. As these aids become more important, carry a spare set to replace a broken or mislaid one.
The problem with reading glasses is that your ability to accommodate differing distances can become more limited over the years. Instrument panels and overhead switch panels are at vastly different focal lengths. I’ve found progressive-correction eyeglass lenses to be a workable solution, allowing various distances to be brought into focus by rocking my head to the exact angle needed to look through the required section of the glasses. It takes time to adjust to progressives, but they do work.
A tri-focal lens, with corrections set for 12-inch, 30-inch and infinity, may work almost as well as progressive lenses. The places requiring the most neck-craning are (1) attempting to read labels on an overhead panel, when the close-up correction at the bottom of the glasses is needed, and (2) trying to look down at a ground feature through the side cockpit window, when the near-vision correction is in the way.
Making regular visits to your ophthalmologist is one way to stay ahead of the game. Regular pressure checks to spot glaucoma early-on is very important. Dry eye irritation is easily treated with eye-drops. If you use contact lenses, be careful to observe length-of-wear limitations and watch for signs of infection. Carry regular glasses with a current prescription to allow changing out of the contacts.
Never rub your tired eyes with your knuckles, particularly in a dry-eye scenario. Instead, massage the facial area around the eyes. When possible, close one eye at a time to briefly lubricate the eye with a drooped eyelid.
Most pilots know the importance of good sunglasses, particularly at high-altitude and above a sun-drenched cloud deck. Those of us who have had to deal with cataracts would advise fellow pilots to employ eye protection anytime you’re out of the clouds. When about to descend into a low cloud layer on an approach, it’s helpful to don the sunglasses to partially dilate the pupils, because the dark gloom below is going to require the most vision you can obtain.
Flash-blindness, or sudden exposure to a bright light when one’s eyes are dark-adapted, can be a real night-flying hazard, particularly in single-pilot operation. Fully recovering from loss of night vision can take 30 minutes or more. In the days when dealing with thunderstorms in unpressurized aircraft meant getting up close and personal with lightning, young copilots were advised to drop their seat to the lowest position behind the glareshield, pull the bill of their cap down, and be ready to close one eye to save at least some of their vision.
The hazard of laser-pointing terrorism, a progression from the childhood prank of shining a flashlight up toward an airplane on its approach to landing, has required serious countermeasure actions lately. Looking directly into a laser beam can do serious eye damage; the natural reaction to an unexpected illumination in the cockpit is to look toward the light. Instead, it’s important to focus away from it until it departs.
Ground operation at night on a busy airport presents many hazards, even with normal vision. Having a landing light or strobe flash turned directly into one’s eyes can result in loss of acuity or depth perception. While taxiing at night, be as respectful as you can with your lights when around other airplanes. Most SOPs require the use of strobe lights while occupying a runway, to avoid any possibility of ATC or another pilot assuming the runway is clear, but give as much space as possible before hitting the switches. Douse the big landing lights as soon as they are not needed after rolling off onto the exit, especially if you see a taxiing aircraft ahead.
When can you do to enhance safety if low visibility is an issue? Keep the cockpit maplight or hand-held flashlight ready to verify a chart or diagram. If flashed by an external light, look toward the taxiway centerline, where your taxi light may be most effective, and maintain your orientation. Stop if you’re not sure your wingtip is going to remain clear.
The opposite of low-light operation is flying sunward, when the bright glare pouring through the windshield obscures vital details. It helps to have a clean windshield, and freshly-cleaned sunglasses, as well as correctly-positioned sunvisors. Fog and mist with sunlight breaking through are difficult glare-producing situations, and, if forced to use a runway oriented into the sun, be particularly alert for looming hazards seen at the last second.
Fading visual acuity can be partially offset by experience, fortunately, but one has to understand the limitations that exist in later years. Take care of your eyes; they are key to success and survival in aviation.