What is Civil twilight?

Civil twilight is the period when the sun is up to 6° below the horizon; in UK aviation, night begins 30 minutes after sunset, at the end of evening civil twilight.

Civil twilight is the period just after sunset, or before sunrise, when the sun is between the horizon and 6° below it and there is still useful natural light. For UK aviation purposes, "night" is defined as the period from 30 minutes after sunset to 30 minutes before sunrise, effectively the end of evening, and start of morning, civil twilight.

This matters because flying at night requires a night rating or qualification, and many clubs and schools restrict bookings around these times.

flyWilco shows twilight times on every booking →