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Aviation History
1974
1974 - 0009.PDF
FLIGHT International, 3 January 1974 Private Flight Fly by night' T HE IDEA of making a night flight for the first time often comes over the pilot as a sudden inspiration. Why not? There are fewer planes in the sky at night, less turbulence, usually better weather, fewer guys hogging the frequencies, less traffic in the pattern, and with the kind of light ing used nowadays an aircraft can stand out like a Christmas tree in a coalmine. All true, but there are some problems. Flying at night means operating in a very different environ ment from the one we meet in day time. In fact, night flying is very like instrument flying, in that your reference to the ground is usually negligible. Most of the time (except for bright moonlit nights) you cannot see the ground at all. What you see are lights and lighted objects only, no horizon, little or no detail of the landscape. You might be able to spot another aircraft 50 miles away, but you could miss a hunk of timber 50 feet away. One of the great potential dangers in night flying is disorientation. On the ground we are so accustomed to adapt ing ourselves to the reduced level of illumination at night that we make necessary adjustments more or less unconsciously. Nevertheless if we are caught in an unexpected blackout, we are apt to panic. The VFR pilot who flies at night must adjust to relying on his instruments for controlling his aircraft attitude; what he can see of the darkened earth below will be of little help, and perhaps misleading. Taking off into darkness, the pilot abruptly passes out of the range of visible reference to the ground, and unless he can keep his wings level and his climb angle true by watching his instruments his flight is liable to terminate prematurely. Conversely, pilots who extend a flight beyond sundown because the sky still seems well illuminated with twilight are sometimes rudely sur prised by the lack of visibility at ground level when they attempt a landing. The phenomenon known as "dark adaptation" of the eye does not take place at all at once, and may require more time than the descent of the aircraft. •adapted from an article in FA A Aviation News Flight Planning Preparation for a safe night flight requires more pre-fiight effort on the part of the pilot than a daytime VFR flight in almost all aspects. An extra margin of safety is the watchword here, since errors cannot always be visibly detected. The fuel reserve should be more than adequate, to allow for some wandering off course. Ceiling and visibility minima may be doubled by cautious pilots. Frontal storm areas should be given a wider berth than in daytime, since clouds cannot often be seen at night until they are already at hand; pre cipitation should be avoided like the plague for VFR flying. It is a good idea to choose a route that you have already flown over in daylight, so that in the event of an emergency landing you will have some idea of what the terrain below is like. Airports along the way should be carefully plotted, on paper as well as in your mind. Use a heavy black marking pencil on the chart, for easy identification. Avoid flying over large bodies of water at night; it is almost impossible to ditch an aircraft success fully in the dark. Taking a passenger along, preferably another pilot, is an excellent safety measure. Visual Adaptation Most people require about half an hour of exposure to total darkness before their eyes achieve their maximum dark adaptation. Dashing from a brightly lighted terminal into a dimly lit cockpit will not give you all of your potential seeing ability for a night take-off. Plan to sit in the cockpit \for some time, going over your charts, drinking coffee, or just relaxing. Smoking is not a good idea, since this may reduce your vision slightly. Fatigue will also affect vision, and if you have spent the day in glaring sunlight without the protection of proper sunglasses you are really ill- prepared to fly at night. A pilot can lose from 30 to 50 per cent of his night vision after several hours of exposure to bright sunlight, especially in a highly reflective environment, such as sand, sea or snow. The effect is cumulative, and repeated exposure may leave you with poor night vision for as long as a week. Recovery normally follows simply as a result of resting the eyes or protecting them from bright light. Incidentally if you own glasses for near vision, you should have them with you at night, even though you may not normally need them during the day. Reduced light levels make it more difficult for the eye to focus on small objects or print. Some aircraft are equipped with red lights in the cockpit, as an aid to adapting the eyes for seeing in the dark, but remember that such light will make it impossible to read any marking in red. The Flight Familiarise yourself with the run way layout before you start to taxi. It is quite embarrassing to get lost just trying to find the active runway in the dark. Taxi more slowly than normal, in view of the reduced visibility. Before you open the throttle make sure that you can read all of the instrument faces easily and clearly, and that you can locate all of the knobs, levers, switches, which you may need, visually as well as manually. If the engine does not sound just right, or the radio trans mission is faulty, taxi back to the ramp and check everything out. When you do take off realign your gyro compass with the runway before you break ground. Keep the turns fairly shallow and the airspeed up where it belongs. Landing Most landing accidents at night result from an approach that is too low. During a visual night approach the pilot's eye is on the airport and the adjacent town lights; the ground below him may not be lighted at all and be invisible. If his altimeter is not set exactly for local conditions, or if he drops below the desirable angle of glide, he may strike wires or trees on the approach. Many experienced night pilots set up their final approach to touch down well beyond the threshold after dark, knowing that if they err in this direction they can always go around again, whereas a too shallow approach can place them in contact with an immovable object.
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