GMDSS qualification limited to Sea Area A1 (VHF DSC range only).
Regulatory detail & full definition
GMDSS Restricted Operator's Certificate under STCW Reg. IV/2 — qualified only for service in Sea Area A1, the VHF DSC range out to typically 20–30 nautical miles from a coast station. The ROC course covers VHF voice, VHF DSC, NAVTEX, and 406 MHz EPIRB / SART operation. The ROC is the standard radio qualification for officers on coastal trading vessels and for yacht masters operating commercially. Holders cannot operate MF/HF or satellite GMDSS equipment beyond elementary distress functions.