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

Under the Global Maritime Distress and Safety System (GMDSS), a compulsory VHF-DSC (Digital Selective Calling) radiotelephone installation is required to be tested daily while at sea. This daily testing is crucial to ensure that the equipment is functioning properly and is ready for use in case of an emergency. This requirement stems from the need for reliable communication in distress situations, where delays caused by malfunctioning equipment could have dire consequences.

Daily testing typically involves checking the functionality of the equipment, including verifying that it can transmit and receive distress alerts and communications. Keeping the equipment in good working order is vital for all vessels operating under GMDSS regulations.

Other frequencies of testing, such as monthly or annual, may be relevant for different checks or inspections, but the daily requirement emphasizes the urgency and importance of readiness in maritime operations.