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

Loss of Inmarsat-C on a Miami-Panama voyage is most likely due to a shipboard equipment fault. The vessel remains within the Western Atlantic satellite coverage area throughout the voyage, and Inmarsat-C coverage is extensive, making it improbable that the vessel has sailed out of range or that a land station is the cause.