The Air Almanac contains the astronomical data required for air celestial navigation. The book provides the following data tabulated at 10-minute intervals to a precision of 1 arcminute: the Greenwich hour angle and declination of the Sun, Moon, and three navigational planets; the Greenwich hour angle of Aries; rise and set times of the Moon for a range of latitudes; and other data. Each edition also contains sky diagrams for each month; sunrise, sunset, and twilight tables; and positions of the navigational stars. The Air Almanac is available nine months in advance of its edition date.
The 2006 and 2007 editions of The Air Almanac consist of the printed publication plus a CD-ROM version. The CD-ROM contains the same information as found in the printed publication, but in Portable Document Format (PDF). Beginning with the 2008 edition, The Air Almanac is available only in the CD-ROM version. It is expected that those requiring a paper copy of certain pages will have access to a printer.
Increased printing costs of The Air Almanac and a survey of user needs were factors considered in the U.S. Naval Observatory's decision to produce The Air Almanac on CD-ROM.
The history of The Air Almanac is found here.