|CHAPTER 12. Night Operations
Unique WSC Flight Characteristics
If the WSC aircraft is trimmed properly and the pilot is profi cient in the basic fl ight maneuvers of climbs, cruise, and descent procedures, the WSC aircraft speed is easily determined with control bar pressure and position for normal fl ight 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 profi cient 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 fl ight. The pilot must continually provide input to fl y a constant heading even if this control is small corrections. In other words, the pilot cannot level the wings or fl y 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.
In addition to night vision limitations, pilots should be aware that night illusions could cause confusion and concerns during night fl ying. 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]
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 fl ight 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 fi eld. It is a good procedure to vary visual focus and not become fi xed on one source of light.
Distractions and problems can result from a flickering light in the fl ight deck, such as anticollision lights, strobe lights, or other aircraft lights which can cause flicker vertigo. If continuous, the possible physical reactions can be nausea, dizziness, grogginess, confusion, headaches, or unconsciousness. The pilot should try to eliminate any light source causing blinking or fl ickering problems in the fl ight deck.
A black-hole approach occurs when the landing is made from over water or unlighted terrain on which runway lights are the only sources of light. Without peripheral visual cues to help, pilots have trouble orienting themselves relative to Earth. The runway can seem out of position (downsloping or upsloping) and, in the worst case, result in landing short of the runway. If an electronic glideslope or visual approach slope indicator (VASI) is available, it should be used. If navigation aids (NAVAIDs) are unavailable, careful attention should be given to using the fl ight instruments to assist in maintaining orientation and a normal approach. If at any time the pilot is unsure of his or her position or attitude, a go-around should be executed.
Bright runway and approach lighting systems, especially where few lights illuminate the surrounding terrain, may create the illusion of less distance to the runway. In this situation, the tendency is to fl y a higher approach. Also, when fl ying over terrain with only a few lights, it makes the runway recede or appear farther away. With this situation, the tendency is common to fl y a lower-than-normal approach. If the runway has a city in the distance on higher terrain, the tendency is to fl y a lower-than-normal approach. A good review of the airfi eld layout and boundaries before initiating any approach helps the pilot maintain a safe approach angle.
Illusions created by runway lights result in a variety of problems. Bright lights or bold colors advance the runway, making it appear closer. Night landings are further complicated by the diffi culty of judging distance and the possibility of confusing approach and runway lights. For example, when a double row of approach lights joins the boundary lights of the runway, there can be confusion where the approach lights terminate and runway lights begin. Under certain conditions, approach lights can make the aircraft seem higher in a turn to fi nal than when its wings are level.
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