Night Operations
Familiarization
Night Vision Techniques
Once your eyes are effectively adapted for night vision, take care to maintain that adaption until you have
completed the flight. Avoid looking directly at brightly lighted areas because even momentary exposure
will adversely affect your night vision. During the flight, keep the cockpit and instrument lights at a low
intensity that permits you to see the instrument indications clearly but avoids canopy glare. Also, be sure
to use the red lens with your flashlight.
Even when your eyes are completely adapted for night conditions, you will see objects as indistinct shapes
in varying shades of grey. You won’t be able to see an unlighted object if you look directly at it; however, if
you shift your eyes to slightly above or below an object, you may then be able to detect it. To perceive
depth and relative motion accurately is extremely difficult at night, so exercise care to avoid setting up
excessively high rates of closure and descent.
OXYGEN
Essential to good vision, especially at night, proper oxygen flow cannot improve your night vision beyond
your normal limits, but it does help to sustain night vision by supplying the blood stream with required
amounts of oxygen that may have been depleted by smoking or fatigue.
Additionally, as altitude increases, the reduced oxygen in the ambient air has a noticeable effect on night
vision, so be sure to use oxygen from takeoff to landing. Along with oxygen, vitamin A, physical fitness,
clean windshields, and clean visors all improve your night vision abilities.
VERTIGO
Aviators can experience vertigo while flying during the day with good visibility. Some pilots have even
experienced vertigo while taxiing. However, night flying combines all of the elements likely to cause
vertigo: poor visibility is a frequent cause of vertigo, as are fatigue, anxiety, and hypoxia.
In a common vertigo experience, you feel as though you are in a turn, but upon checking your instruments,
you see that you are flying straight and level. Another sensation of vertigo fits the pattern known medically
as the Coriolis phenomenon: for example, as you look down and adjust some controls that are slightly
behind and to one side of you, the aircraft rolls slightly to one side, and when you straighten up and look
ahead you experience vertigo. These impressions are increased during letdown or when you are
performing penetration turns, so whenever possible, set up the cockpit before beginning such maneuvers.
You can also experience vertigo when you suddenly go from an area of good light reference to an area
with few or no external light references, say, as you suddenly lose sight of airfield lights after takeoff or in
the break. Many cases of vertigo involve confusion of ground lights and stars, an illusory sense of lights in
motion, errors in locating lights, and misjudging the position of clouds. Haze and adverse lighting condi-
tions obscuring the horizon can also cause vertigo.
The experience of vertigo can vary greatly in duration and intensity, lasting only a few seconds in minor
instances or over an hour in extreme situations. Although vertigo may continue after straight and level
flight has been established, eventually it will disappear, and it can always be countered.
Your most important and reliable method of safely countering vertigo is to discipline yourself to have full
confidence in your flight instruments. Trusting your instruments is always the answer if you experience
vertigo while in flight. Believe what you see on your instruments, not what you feel.
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