Why Twilight Can Be a Complicated Time for Pilots

Do you know the difference between civil twilight, nautical twilight and astronomical twilight?

Peter Garrison

Thursday, February 15, 2018 at 08:00 PM ET

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Twilight is partitioned into three zones: civil, nautical and astronomical. Pexels

Key Takeaways:

The article details multiple fatal aviation accidents stemming from poor pilot judgment during night flights or in extremely low visibility conditions like dense fog.
Incidents included pilots attempting to land at unlighted airstrips, flying in pitch darkness, or encountering severe weather, leading to collisions with trees or terrain.
Contributing factors often involved insufficient experience, navigational challenges in darkness, and dangerous visual illusions such as the "black-hole effect" during landing approaches.

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Twilight is a complicated thing. It is partitioned into three zones. There is civil twilight, which lasts from sunset to when the center of the sun is 6 degrees, or about 12 solar diameters, below the horizon and things can no longer be clearly seen.

Then comes nautical twilight, which ends when the center of the sun is 12 degrees below the horizon and a seaman no longer discerns the break between the western sea and the sky. Finally, astronomical twilight ends when the sun is 18 degrees below the horizon, leaving the sky black enough for the inspection of distant galaxies.