SITOR equipment is a full, partial or alternate carriage requirement under GMDSS for vessels operating in which sea area(s)?

Correct Answer: Option C — A3 and A4

SITOR (Simplex Teletype Over Radio), also known as NBDP (Narrow Band Direct Printing), is a mandatory carriage requirement for vessels in Sea Areas A3 and A4. It provides a reliable method for receiving Maritime Safety Information and general communications when satellite or VHF coverage is insufficient or as a redundant system.