Daytime Black Holes

demonstrating how the black-hole approach effect works in daytime conditions."

Glenn Grubb

Friday, September 22, 2017 at 12:00 AM ET

Verified

Key Takeaways:

Optical illusions, particularly the "black-hole illusion," pose significant hazards in aviation by distorting a pilot's perception of their glideslope and position.
While commonly associated with night landings over unlit terrain, the black-hole illusion can also occur during daytime approaches, especially to upslope runways.
This illusion tricks the brain by misinterpreting changes in the runway's visual angle, leading pilots to mistakenly perceive themselves as too high and subsequently fly a dangerously shallow or "drooping" approach.
Pilots must understand and anticipate these perceptual distortions to maintain stabilized approaches and prevent landing short of the runway.

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Optical illusions are all around us. A classic example might be when looking through a camera and a slow-turning airplane propeller or the wheel spokes on a car appear to slow and then reverse direction. None of that happens, of course; part what we “see” is determined by how well our eyes and brain work and play together. The bad news is there are many other optical illusions, and they can actually be quite dangerous if encountered while flying. The good news is we can understand them, anticipate them, then compensate for them.