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In addition to the principles previously discussed, the following actions aid in increasing night vision effectiveness: 

• Adapt the eyes to darkness prior to flight, and keep them adapted. About 30 minutes is needed to adjust the eyes to maximum efficiency after exposure to a bright light. 

• Use oxygen during night flying, if available. Keep in mind that a significant deterioration in night vision can occur at altitudes as low as 5,000 feet. 

• Close one eye when exposed to bright light to help avoid the blinding effect. 

• Avoid wearing sunglasses after sunset. 

• Move the eyes more slowly than in daylight. 

• Blink the eyes if vision becomes blurred. 

• Concentrate on seeing objects. 

• Force the eyes to view off center. 

• Maintain good physical condition. 

• Avoid smoking, drinking, and using drugs that may be harmful. 

##  Unique WSC Flight Characteristics 

If the WSC aircraft is trimmed properly and the pilot is proficient in the basic flight maneuvers of climbs, cruise, and descent procedures, the WSC aircraft speed is easily determined with control bar pressure and position for normal flight conditions. A pilot can also determine basic climbs and descents through the feel of the aircraft with the airspeed and throttle positions. Therefore, basic pitch control can be done by a proficient pilot with his or her eyes closed. 

As discussed in Chapter 2, Aerodynamics, WSC aircraft are generally not designed to be roll stable, and any engine turning effect or movement of the air can put the WSC aircraft into a roll, which it maintains unless corrected by the pilot. In other words, releasing the control bar in a WSC aircraft will not level a bank back to straight flight. The pilot must continually provide input to fly a constant heading even if this control is small corrections. In other words, the pilot cannot level the wings or fly a straight heading for very long with his or her eyes closed. 

To maintain a constant heading or ground track, one of three instruments can be used: magnetic compass, global positioning system (GPS), and aircraft heading indicator. Without a visual reference, these can be used to fl y straight. An attitude indicator can be used on WSC aircraft providing additional instrument reference. These instruments and others are discussed later in this chapter. 

##  Night Illusions 

In addition to night vision limitations, pilots should be aware that night illusions could cause confusion and concerns during night flying. The following discussion covers some of the common situations that cause illusions associated with night fl ying. 

A false horizon can occur when the natural horizon is obscured or not readily apparent. It can be generated by confusing bright stars and city lights. It can also occur while fl ying toward the shore of an ocean or a large lake. Because of the relative darkness of the water, the lights along the shoreline can be mistaken for stars in the sky. [Figure 12-7] 

<img src='content_image/548714.jpg'>

On a clear night, distant stationary lights can be mistaken for stars or other aircraft. Even the northern lights can confuse a pilot and indicate a false horizon. Certain geometrical patterns of ground lights, such as a freeway, runway, approach, or even lights on a moving train can cause confusion. Dark nights tend to eliminate reference to a visual horizon. As a result, pilots need to rely less on outside references at night and more on flight and navigation instruments. 

Visual autokinesis can occur when a pilot stares at a single light source for several seconds on a dark night. The result is that the light appears to be moving. The autokinesis effect does not occur if the pilot expands the visual field. It is a good procedure to vary visual focus and not become fi xed on one source of light. 

