Question E1A11:
[97.5] What licensing is required when operating an amateur station aboard a US-registered vessel in international waters?  

Choices:  
A: Any amateur license with an FCC Marine or Aircraft endorsement  
B: Any FCC-issued amateur license  
C: Only General class or higher amateur licenses  
D: An unrestricted Radiotelephone Operator Permit    

Correct Answer is  B: Any FCC-issued amateur license  

Correct answer: B — Any FCC-issued amateur license

Why B is correct:
- In international waters, the law of the vessel’s flag state applies. A US-registered vessel is under FCC Part 97 rules, so any valid FCC amateur license (Technician, General, or Amateur Extra) authorizes operation within that license’s band/mode privileges.
- No additional endorsements or commercial permits are required for Amateur Radio operation.

Why the others are incorrect:
- A: “FCC Marine or Aircraft endorsement” does not exist for Amateur Radio. No special endorsement is needed.
- C: It is not limited to General or higher. Technicians may also operate, subject to their privileges.
- D: An unrestricted Radiotelephone Operator Permit is a commercial credential for ship/aircraft stations in the commercial services, not for the Amateur Service.

Useful rules of thumb:
- Law of the flag: In international waters, the vessel follows its flag state’s radio regulations (here, FCC Part 97).
- Territorial sea limit: International waters begin beyond about $12$ nautical miles ($\approx 22.2$ km) from a coastal baseline.
- Identification: Append “/MM” (maritime mobile) when operating at sea, and operate only within your FCC license privileges.