This is for night landing plane on unlighted field ( or when you want visual proof of height or distance from object).
View is overhead of airplane wing, the outside square, underneath wing are angled spotlights are mounted close to wing tips.
Spotlights are aimed toward centerline of plane and also pointed down at ground to light view in front of pilot,(the two connected grounds) .
Plane is in descent and configured for landing. As plane descends two balls of spotlights appear on ground and slowly start moving together. When both lights become together as one the pilot know the height they have been set for 100 feet, 50 feet, ect. and this tells distance above ground terrain. As descent continues the lights cross and move toward light on wing tips.
