What is the first digital sea area under GMDSS?

The first digital sea area under the Global Maritime Distress and Safety System (GMDSS) is defined by the ability of a Very High Frequency (VHF) radio to establish communication with at least one shore station up to a distance of 20 nautical miles from the shore. This specification is critical for ensuring that vessels in near-shore areas can effectively communicate in emergencies, as it establishes a basic requirement for distress signaling and safety communications.

VHF radios are typically used in areas closer to shore due to their limited range compared to other radio frequencies. This makes it essential that vessels operating within this range have access to at least one shore station to ensure that they can receive assistance if needed. By setting the distance at 20 nautical miles, it aligns with the operational capabilities of VHF equipment commonly used in maritime contexts.

The alternative options involve different parameters or radio types that do not specifically define the first digital sea area under GMDSS, as they either refer to varying distances or different frequencies without meeting the first specified criteria for VHF communication. This understanding highlights the fundamental requirements for maritime safety obligations within the GMDSS framework.