Plain English Meaning

A reference book of star, Sun, Moon, and planet positions for every day and time of the year. A navigator uses these tables, along with sightings of those bodies, to figure out where the aircraft is.

Full Definition

A publication, issued jointly by the U.S. Naval Observatory and Her Majesty's Nautical Almanac Office, that provides tabulated astronomical data — including the Greenwich Hour Angle and declination of the Sun, Moon, planets, and selected stars — at regular time intervals throughout the year. It is used in celestial navigation to determine an aircraft's position from observations of celestial bodies.

Context Anchor

Seen in night operations and regulations when determining whether a flight is being made during day, night, or civil twilight.

Derivation

‘Almanac’ comes from Medieval Latin ‘almanachus,’ meaning a calendar or table of astronomical events. ‘’ distinguishes this version from the older Nautical Almanac used at sea — the Air Almanac is formatted for the faster pace of flight, with data tabulated at shorter time intervals so an navigator can find values quickly.