Night approaches to certain airports can mislead pilots over dark, featureless ground
The FAA has a name for the effect that occurs when runway lights appear against unlit terrain or water on a dark approach, leading pilots to fly below the correct glidepath. It has been linked to controlled flight into terrain accidents.
Landing in daylight, pilots have plenty of visual cues to judge their height and distance out. Buildings give a sense of scale, fields show texture, and terrain drifts through the edge of vision while the runway stands out against its surroundings.
After dark, almost all of that is gone. If the ground or water below is unlit, the runway lights may be the only thing a crew can see, with nothing around them to fix their position.
The FAA calls this the black hole effect. It comes from how the brain reads the shape of that lone set of lights, interpreting the pattern as though the aircraft is higher than it really is. The result tends to pull the aircraft below the correct glidepath.
The phenomenon has been a factor in controlled flight into terrain accidents at airports whose approaches cross empty ground or water on dark nights.
Sources
- simpleflying.com5 Airports Where Night Approaches Can Be Especially Disorienting