Describe the difference between a Mayday, Pan Pan Medico and Securite call, giving the correct SMCP opening format for each. When would you use each during your watch?

A. THREE LEVELS OF MARITIME RADIO COMMUNICATION PRIORITY: (1) MAYDAY — Distress: Immediate danger to life or vessel requiring immediate assistance. Format: "MAYDAY MAYDAY MAYDAY, this is [vessel name] [vessel name] [vessel name], MAYDAY [vessel name], my position is [lat/long or bearing/distance], [nature of distress], [number of persons on board], [any other relevant information], over." Transmitted on Ch 16 (DSC first on Ch 70 if GMDSS equipped, then voice on Ch 16). (2) PAN PAN — Urgency: Urgent situation but not immediately life-threatening. Medical emergencies afloat: "PAN PAN PAN PAN PAN PAN, all stations all stations all stations, this is [vessel name] [vessel name] [vessel name], my position is [position], I have a medical emergency — [description of patient and condition], I require medical advice / evacuation, over." (3) SECURITE — Safety: Navigation hazard or meteorological warning. "SECURITE SECURITE SECURITE, all stations [or specific vessel if directed], this is [name / coastguard], [safety message], out." WHEN TO USE: Mayday — vessel sinking, fire out of control, man overboard (if recovery not possible), collision with serious flooding. Pan Pan — medical emergency, vessel disabled but not sinking, person in danger but not yet life-threatening. Securite — unlit vessel, navigational obstruction, ice warning, debris report.

B. Pan Pan and Securite are alternative names for Mayday — they all mean the vessel is in distress. All three are transmitted on Ch 16 and have the same format with different opening words.

C. Mayday is for the vessel, Pan Pan is for crew members only. Securite cannot be transmitted by a merchant vessel — it is reserved for coastguard authorities.

D. Use Mayday for any emergency. Pan Pan and Securite are outdated signals from before GMDSS and are no longer used in practice.

A. IMO STANDARD MARINE COMMUNICATION PHRASES (SMCP 2001): The SMCP is an IMO publication (Resolution A.918(22)) providing standardised English phrases for maritime communications. LEGAL BASIS: SOLAS Chapter V, Regulation 14 requires that officers in charge of a navigational watch on ships required to carry a radio installation shall be proficient in the use of English. The SMCP provides the standardised language to fulfil this requirement. WHEN MANDATORY: (1) VHF bridge-to-bridge communications for collision avoidance; (2) Communications with Vessel Traffic Services (VTS) — initial call, position reports, intentions; (3) Distress, urgency and safety communications on Channel 16; (4) Communications with pilots during embarkation and passage; (5) Port authority and harbour control communications; (6) SAR coordination communications; (7) Communications with other vessels for manoeuvring in restricted waters. STRUCTURE OF SMCP: phrases are organised by function — external communications (VHF), internal ship communications, and safety-related phrases. Responses use standard acknowledgements: "I read you", "Stand by", "Say again", "Received". KEY PRINCIPLE: English is the working language of international maritime communications — if neither party is a native English speaker, both must use SMCP rather than their own language.

B. SMCP are voluntary guidelines produced by IMO. They are only recommended practice and SOLAS does not require their use — captains may use any language agreed between the two vessels.

C. SMCP apply only to communications with shore-based VTS. Ship-to-ship communications may use any mutually understood language including the officers' native languages.

D. SMCP are required only for passenger vessels. Cargo ship officers must be proficient in English but are not required to follow the standardised SMCP format.

A. SMCP COLLISION AVOIDANCE CALL — CORRECT APPROACH: Initial call on Ch 16 (then switch to a working channel, typically Ch 13 or 16): "Vessel bearing [bearing] from me, this is [vessel name] on VHF channel [xx], over." After contact: "I am the stand-on vessel. I intend to maintain my course and speed. Please confirm your intentions, over." OR if you are the give-way vessel: "I am the give-way vessel. I intend to alter course to starboard [or slow down] to pass astern of you. Do you agree? Over." KEY SMCP PHRASES: "I intend to alter course to starboard/port", "I am altering course to starboard/port", "I intend to stop my engines", "Please indicate your intentions." RISKS OF VHF COLLISION AVOIDANCE: (1) VHF agreements are NOT a substitute for COLREGs action — the give-way vessel must act in good time regardless of VHF exchange; (2) VHF agreements can create false confidence — the other vessel may not follow through; (3) Use call sign or vessel name to ensure you are speaking to the correct ship — "vessel ahead" is ambiguous; (4) Rule 8 requires action to be positive, taken in ample time — do not delay COLREGs action waiting for VHF response; (5) Document the exchange in the deck log.

B. Call the vessel on Ch 16 and agree to both alter to starboard. Once agreed by VHF, both vessels should proceed according to the agreement and no formal COLREGs action is needed.

C. VHF should never be used for collision avoidance — it creates legal liability by demonstrating awareness of the risk before action was taken. Use radar and take COLREGs action silently.

D. Use any language common to both bridges. SMCP only apply to VTS communications. Ship-to-ship collision avoidance VHF calls have no standardised format requirement.