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Aviation Glossary :: Twilight  Aviation Glossary :: Twilight FAA Written Test Preparation
Aviation Glossary Welcome to the Dauntless Aviation Glossary!

At Dauntless, our editorial staff maintains the web's largest unified glossary of aviation terms. This glossary is built from a combination of official, quasi-official, and proprietary sources (including original material that we develop oursselves). Uniquely, we often provide multiple definitions of a given term so that you can find that which best applies to you. In order to maximize your learning efficiency, this glossary (and similar ones for our international users) is incresingly fully integrated into our aviation learning apps, including our FAA written test prep and FAA practical test prep software and apps. If you like this glossary, you'll love them with their polished learning environments and world's best and clearest content (please do give them a try.).

Twilight
Twilight
The intervals of incomplete darkness following sunset and preceding sunrise. The time at which evening twilight ends or morning twilight begins is determined by arbitrary convention, and several kinds of twilight have been defined and used; most commonly civil, nautical, and astronomical twilight.
  1. Civil Twilight-The period of time before sunrise and after sunset when the sun is not more than 6° below the horizon.
  2. Nautical Twilight-The period of time before sunrise and after sunset when the sun is not more than 12° below the horizon.
  3. Astronomical Twilight-The period of time before sunrise and after sunset when the sun is not more than 18° below the horizon.
source: FAA Aviation Weather for Pilots (AC 00-6A)
The periods of incomplete darkness following sunset and preceding sunrise. Twilight is designated as civil, nautical, or astronomical, as the darker limit occurs when the center of the sun is below the celestial horizon.
source: FAA Flight Navigator's Handbook (FAA-H-8083-18)
The average time of civil twilight, which is the time between civil dawn and sunrise in the morning, and between sunset and civil dusk in the evening.
source: NOAA National Weather Service Glossary

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