A vessel with an 18-hour ETA to the Panama Canal on a voyage from Miami loses the ability to communicate via Inmarsat. The most likely cause is?

Correct Answer: Option D — An equipment fault.

Inmarsat coverage is global (excluding polar regions). A vessel traveling from Miami to the Panama Canal remains well within the footprint of the Western Atlantic Ocean Region (AOR-W) satellite. Therefore, a sudden loss of communication in this region is almost certainly due to an internal equipment fault rather than satellite coverage.