Definition
The period after sunset that ends when the center of the sun is 6 degrees below the horizon. During this time, the sun is below the horizon but the sky still provides enough natural light to see the horizon clearly and identify prominent terrestrial objects without artificial light.
Plain English
The window of fading light between sunset and full darkness. The sun has gone down, but it is not yet truly dark — you can still see the horizon and major features on the ground.
Context Anchor
Seen in night flying discussions, pilot logbook rules, and flight planning when deciding whether a flight occurs during daytime, twilight, or regulatory night.
Derivation
Civil' here means 'for ordinary daily use' — the same root as 'civilian.' Civil twilight is the version of twilight defined for everyday purposes (like aviation and driving), as opposed to nautical or astronomical twilight, which use larger sun angles and are used by sailors and astronomers.
Why Pilots Care
Determines when aircraft lights must be on and when night flight experience can be logged for currency.
Grounding Statement
Picture standing on a ramp ten or fifteen minutes after sunset: the sun is gone, the sky is dimming, but you can still clearly see the runway, the trees at the field boundary, and the horizon line. When that horizon finally fades into the sky — that's the end of evening civil twilight.
Intuition Check
Do not assume evening civil twilight means “whenever it seems dark outside.” In aviation, it is based on the Sun’s calculated position below the horizon and is published as a specific time.
Example Sentence 1
He planned the cross-country to land well before the end of evening civil twilight so the flight would still count as day flying.
Example Sentence 2
Night currency requires three takeoffs and landings after evening civil twilight ends if the pilot wants to carry passengers at night.