Flight Training - October 2011 - 32

OPTICAL ILLUSIONS TO AVOID AT NIGHT
AUTOKINESIS: Caused by staring at a stationary point of light for several seconds or longer, which can cause the light to appear to be in motion. Prevention/remedy: Avoid fixing your focus on any one object for more than a few seconds. Maintain a normal visual scanning pattern at night, just as you would during daylight hours. FALSE HORIZON: Caused by an obscured natural horizon being mentally replaced by bright stars or artificial lighting on the ground, especially along a shoreline. Prevention/remedy: Pilots must allow for an increased reliance on their instruments when flying at night. Whenever we are in flight at night, we must base our situational and spatial orientation on the information those instruments provide, not on our personal feelings or assumptions. NIGHT LANDING ILLUSION 1: Mistaking regularly spaced lights on the ground, such as street lights, for the runway. This illusion can cause the pilot to initiate an approach to landing in a place that is not intended for low-flying aircraft. NIGHT LANDING ILLUSION 2: Rain, haze, a darkened runway environment, or featureless terrain can lull a pilot into flying a lower-than-normal approach. NIGHT LANDING ILLUSION 3: Wide runways, steep terrain surrounding the runway, or bright lights all can cause a pilot to fly a higher-than-normal approach. Prevention/remedy: Positively identify the airport and the runway environment using multiple indicators, if possible. Verify the field elevation, and fly a standard approach using altitudes that are appropriate to that elevation. Verify that the pressure set into the altimeter’s Kollsman window is accurate to the local area before beginning your descent. Include a cross-check of the altimeter into your traffic pattern practices and procedures, with a special emphasis on specific, safe altitudes when turning base and final. Use a precision approach path indicator (PAPI), visual approach slope indicator (VASI), or any other lighted approach-path system to your benefit.

sun reaches the horizon, morning civil twilight ends. In the official sense, it’s the time between the ending of one, and the beginning of the next, that we call night. CFIs have historically encouraged students to begin logging their flight time as night time one hour after sunset, right through to one hour before sunrise. This isn’t a particularly scientific rule, but it works, and it’s easy to remember. For certificated pilots, the FAA formalizes that idea in Federal Aviation Regulation 61.57(b), which requires the pilot in command—before carrying passengers during the period beginning one hour after sunset and ending one hour after sunrise—to have logged, within the preceding 90 days, at least three takeoffs and landings to a full stop during that period. (One other time period to remember is sunset to sunrise; that’s when your aircraft’s position lights must be illuminated.) In the old days a student pilot could opt out of the night training requirement. That is not an option any longer. The only exception to the night training requirements these days comes in the form of a temporary limitation, and a short stay. Applicants who train and live in Alaska, where night is considerably less consistent on a daily basis than it is in the lower 48, can be issued a private pilot certificate with a limitation reading, “night flying prohibited.” But even with that limitation on their certificates, Alaskan private pilots are required to receive and log the appropriate night training within 12 months after the certificate is issued. If they fail to comply, their pilot certificate becomes invalid until they complete that training. In addition to those basic night training requirements, there are two additional numbers that are important for pilots to remember when flying at night. The first number is, 10 seconds. The second is, 30 minutes. It takes approximately 10 seconds for the average pilot’s eyes to adjust from the darkness to the light. That can be good and it can be bad, depending on the situation. If you’re walking out of a dark theatre into

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Flight Training - October 2011

Table of Contents for the Digital Edition of Flight Training - October 2011