NAVTEX Frequencies

International NAVTEX broadcasts on 518 kHz in English, providing maritime safety information to GMDSS Sea Area A1 / A2 within roughly 200–400 nautical miles of a transmitter. Optional national broadcasts use 490 kHz in the local language; tropical broadcasts use 4209.5 kHz where atmospheric propagation favours HF. Each NAVTEX area is assigned a transmitter identification letter (e.g. 'O' for Cullercoats UK), and broadcasts are scheduled in time windows to avoid interference. ITU Radio Regulations Appendix 17 specifies the technical parameters; SOLAS Reg. IV/12 requires GMDSS-compliant ships to carry NAVTEX receivers.