Module 5 - Routine Calls
The Shape of a Complete Routine Call
With a known vessel MMSI, MCA guidance uses an Individual DSC call with routine priority and a proposed inter-ship channel. After acknowledgement, the conversation starts on that accepted channel. With an unknown MMSI, make a brief low-power voice call on Channel 16, then move to an appropriate inter-ship channel after contact.
A coast station using DSC controls its working voice route: send an Individual DSC routine call to the published MMSI, accept the acknowledgement, move to the indicated channel and wait for the coast station's voice call. A marina or harbour call instead follows its current published local service procedure.
Across all three routes, the human factors are the same: prepare, listen, identify, leave reply space, confirm any channel move, exchange only useful information, read back critical instructions and restore the required watch when complete.
| Stage | Operator action | Failure to avoid |
|---|---|---|
| Prepare | Station, identity, purpose and current channel route | Improvising a long message while transmitting |
| Listen | Check the route is clear and note higher-priority traffic | Talking over an existing exchange |
| Call | Identify the called station and own vessel briefly | Giving all detail before acknowledgement |
| Move | Accept or agree the correct working channel and confirm the display | Using Channel 70 for speech or staying on 16 |
| Exchange | Give concise facts and read back critical instructions | Guessing an unreadable group |
| Close | Use the correct proword, release PTT and restore the watch | Leaving the set on an unintended channel |
Optional quick check
Section 5 of 10
A known-MMSI routine DSC call is acknowledged on the proposed inter-ship channel. What follows?
Sources and factual review
Reviewed 20 August 2026 - Compass Revision editorial review.
Continue studying Routine Calls
This public lesson is part of Revision Module 5. Full revision access adds the guided Learn, Practise and Test flow, flashcards and revision progress.