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Feature Article: Night Illusions

Runway and approach light illusions will always be a problem if you are in an unfamiliar area. For this reason it is always desirable to make a daylight familiarization flight to an airport before a first time night arrival. Night has its own illusions that are covered in the night flight lessons. The distance of lights is greatly affected by the relative clearness and haze existing. A region of no lights such as might exist off the end of a runway toward the ocean can cause disorientation because of IFR illusions. The best solution is to go on instruments until established inland at altitude.
Variable Visibility
If, while on approach, you should suddenly face reduced visibility you will get an illusion of a sudden pitch up in aircraft attitude. Failing to recognize this illusion will lead to an instinctive and abrupt descent in the approach flight path.

Your ability to determine distance is greatly affected by haze. It is not unusual to call a distance at over twice the actual distance. The sudden appearance of bright lights during an a night approach through haze will create the illusion that the airport is much closer than previously realized. This results in a high approach.
If there is no VASI or VAPI for vertical guidance if you get too low the runway lights will begin to disappear. A steep approach is always better at night. An arrival at an airport with and approach lighting system (ALS) tends to be lower and at a shallower angle than otherwise. Low approach results when runway is approached over dark area. Don't use landing light until close to ground. The visual cues used for a normal night landing seem much the same as you get with a rapid increase in sink rate.
If there is a strong crosswind and you are crabbing to the runway instead of slipping you will get the illusion of being inverted. If the airport is well lighted in a surrounding dark area you will have an illusion of being higher than you actually are. Again a steep approach has much advantage.
Rain on the windshield will give the illusion of being higher than you are. If you mistake roadways for runways. It will give illusion of being quite close when lights are bright. High approach results.
If you are low and pitch the nose up as a correction or through the use of flaps, the illusion will indicate that you are rising. Any reduction of power will cause you to land short.
At night, banking into or away from a line of lights will give the illusion that a dive or a climb is occurring. The same dive or climb illusion can happen by a change in aircraft pitch occurs while flying toward a light.
A 10 degree bank with only the approach lights visible can cause an illusion that the lights are sloping from above.
Lights that appear dim, as seen through haze, will be reported as more distant than they are. Example: I once reported an airport as in sight from twelve miles when the tower had me on radar at only five miles.

Last Modified April 14, ©2021 TAGE.COM

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