Zulu Time
F5. The Reference Layer: Glossary, Units, Signals and Information SourcesDefinition
Coordinated Universal Time (UTC), the navigation reference.
Zulu time is Coordinated Universal Time (UTC), denoted by the phonetic letter Z for the zero time zone. It is the single reference for celestial navigation almanac entries, weather products, NAVTEX and Inmarsat safety messages, AIS time stamps, and the ship’s official log of events. UTC is kept to within 0.9 s of mean solar time by leap seconds and is derived from International Atomic Time (TAI). A position report or distress message always carries the time in UTC to avoid zone ambiguity.