ALRS

The Admiralty List of Radio Signals (ALRS) is the UKHO’s six-volume reference covering the maritime radio services a bridge team uses for communications, position fixing, and safety information. The volumes run: Vol 1 coast radio stations, Vol 2 radio aids to navigation including satellite navigation and legacy systems, Vol 3 maritime safety information services, Vol 4 meteorological observation stations, Vol 5 the GMDSS, and Vol 6 pilot services, vessel traffic services, and port operations. Each volume carries an annual edition plus weekly corrections through Admiralty Notices to Mariners. The ALRS is the standard companion to the chart for working out which station, frequency, and schedule to use.