Under GMDSS, a compulsory VHF-DSC radiotelephone installation must be tested at what minimum intervals at sea?

The correct interval for testing a VHF-DSC radiotelephone installation under the Global Maritime Distress and Safety System (GMDSS) is weekly. This requirement ensures that the equipment is functioning properly and can effectively transmit distress and safety communications in an emergency situation at sea. Regular testing enhances the reliability of the communication system, which is critical for maritime safety.

Conducting these tests at a minimum of weekly intervals allows vessel operators to identify any potential issues early, ensuring that the system is always ready for use when needed. Regular checks are an essential part of maintaining operational readiness and ensuring compliance with safety regulations set forth by the International Maritime Organization (IMO) and the FCC.