Message markers in VTS communication
1The lesson in plain words
A message marker tells the listener what kind of message follows. Using the wrong one can turn a suggestion into an order, or an order into a suggestion.
Why markers
A Vessel Traffic Service (VTS) is a shore service that monitors traffic and talks to ships in its area. When a standard phrase does not fit, or the purpose of a message could be misread, a message marker is spoken before the message or the relevant part. The speaker chooses whether and which marker to use. IMO VTS guidelines ask that every message to a ship makes clear whether it is information, advice, warning or instruction.
Instruction and advice
INSTRUCTION gives an order under a regulation. The sender must have authority to give that order. Follow it unless you have a conflicting safety reason; report that reason to the sender. ADVICE gives a recommendation. You decide whether to follow it, but consider it carefully. Reply to either with ‘I will …’ or ‘I will not …’ and the content in full.
Warning and information
WARNING draws immediate attention to a danger: ‘WARNING. Obstruction in the fairway.’ INFORMATION is limited to observed facts, mostly navigational and traffic information: ‘INFORMATION. MV Noname will overtake to the west of you.’ What you do about either is your decision, so plan and report your action.
Question and answer
QUESTION removes any doubt that you are asking: ‘QUESTION. What is your present maximum draft?’ ANSWER marks the reply: ‘ANSWER. My present maximum draft is one-two decimal five metres.’ An answer must not contain another question. If you need to ask back, send a separate QUESTION.
Request and intention
REQUEST asks for something to be arranged or provided: tugs, stores, permission. Never use REQUEST for navigation. For navigational permission, use QUESTION. No message marker changes your duties under the COLREGs. INTENTION announces navigational action you are about to take with your own vessel: ‘INTENTION. I will reduce my speed.’ It never announces what another vessel will do.
2Key data
- Must follow (unless unsafe)
- INSTRUCTION, from an authorised sender
- Decision stays with you
- ADVICE, WARNING, INFORMATION
- REQUEST
- Arrangements or supplies; never navigation or COLREG changes
- INTENTION
- Your own vessel’s immediate navigational action
- ANSWER
- Must not contain another question
3Key points
- 1
Markers are optional, chosen by the speaker, and spoken before the message they label.
- 2
Follow an INSTRUCTION unless safety forbids it, and then report your reasons.
- 3
ADVICE is a recommendation: you decide, but you consider it very carefully.
- 4
Never use REQUEST for navigation; ask permission with a QUESTION.
4Frequent mistakes
Wrong: ‘REQUEST. I will overtake the vessel ahead.’
Right: Navigation is not a request. Ask ‘QUESTION. Do I have permission to overtake …?’ or announce ‘INTENTION. I will …’ where no permission is needed.
Wrong: Treat a VTS ADVICE as an order you cannot question.
Right: ADVICE leaves the decision with you. Reply ‘I will …’ or ‘I will not …’ with the advice in full, and give your reason if you decline.
Wrong: Ignore an INSTRUCTION you think is unsafe.
Right: Do not just ignore it. Report your contradictory safety reasons to the sender at once.
5Practice case & exam keys
VTS sends ‘ADVICE. Anchor in B3.’ Your assessed draft leaves too little under-keel clearance, the gap between your keel and the seabed, there. What do you reply? Would an INSTRUCTION remove that concern?
Show the answer
‘I will not anchor in B3. Insufficient under-keel clearance.’ Report your safe alternative and coordinate it with VTS. ADVICE leaves the decision with you. An authorised INSTRUCTION must normally be followed, but a conflicting safety reason still requires you to report why you cannot comply.
Exam keys
- Eight markers: INSTRUCTION, ADVICE, WARNING, INFORMATION, QUESTION, ANSWER, REQUEST, INTENTION.
- INSTRUCTION: authorised sender; follow unless contradictory safety reasons, which you report.
- REQUEST never for navigation or to modify COLREGs; ANSWER never contains a question.
- INTENTION: your own vessel’s immediate navigational action.
Finish this unit
When you've read it, answer three questions. Get all three right to finish the unit; opening the page alone doesn't count.
My notes for this unit
No notes