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 dangers in aviation by deceiving pilots about their altitude and glideslope, potentially leading to errors like landing short of the runway.
The black-hole illusion occurs when limited peripheral visual cues (e.g., night flying over unlit terrain) or specific runway conditions cause the brain to misinterpret the runway's visual angle, making the pilot feel too high and prompting a dangerously low, "drooping" approach.
Crucially, this illusion is not exclusive to night flying but can also manifest during the day, especially when approaching upslope runways or those elevated above surrounding terrain, due to similar visual angle misinterpretations that make the runway appear to "grow" in length.

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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.