Private Pilot Flight Training and Instruction Flight Training Article Library | Back To 4VFR.COM Black Hole Landing When it is very dark you are subject to illusions. Your seat position may make you more or less subject to these. Aircraft seats are situated by a "Design Eye reference Point" (DERP) that is supposed to give a view over the cowl and at the instrument panel. It is not marked on the aircraft but is part of the aircraft design. If your seat is too low during dark conditions, you will only be able to see runway lights if you are in a descent. The pilot tends to set up a constant angle for their field of view on approach. During daylight, you use the "point on the windshield" to maintain this angle. If the aim point drifts upward you are in an excessive descent; if it drifts downward you are too high. It works the same at night but the references are fewer. The black hole illusion begins out a few miles on final. The field and lights will be foreshortened. Getting closer the runway should rise in the field of view. If the aircraft is descending the foreshortened view will remain constant. The eye/brain interpretation of this is that the constant foreshortened runway is an indication of a constant angle approach. This is the "everything is fine" illusion of the black hole. During the final phases the daytime depth perception does not work very well. When flying into a black hole or 'featureless terrain' you must use a correctly set altimeter to counter the illusion. Fly a full pattern using your altimeter and a standardized procedure for a stabilized approach. This is the best way to assure yourself that you will not meet an obstacle on final. This is a combined IFR/VFR approach and requires that you be capable of controlling the aircraft accurately without visual references. The normal order of viewing runway, lights, and dark areas is so changed illusions of being higher occur. If the illusions are believed, touchdown can occur before reaching the runway. The "black hole illusion" has a dramatic effect on straight in approaches to a runway. The stabilized constant angle approach will appear to exist as an illusion while you fly an arc that flies you into the ground. Do not fly a straight in approach to a runway at night. Know the pattern altitude. Fly somewhat farther out on down wind than appears appropriate. Use a standardized configuration approach just as you would in daytime. Fly the VASI or VAPI if available. Failure to follow the above recommendations may cause you to make a premature descent. Over flying featureless terrain without lights on an approach that deprives you of the height clues can fly you into the ground. Aircraft Illusions There are some optical illusions that relate to nearby aircraft. An aircraft below you will appear to be above you. While getting closer it will appear to descend through your horizon. All the time it is straight an level below you. Avoid the temptation to dive. Written by Gene Whitt Flight Training Article Library | Back To 4VFR.COM