Answer
FSI (Flag State Inspection): This inspection is conducted by flag state surveyors or appointed Recognized Organizations (RO) representing the country where the vessel is officially registered (e.g., an Indian surveyor checking an Indian-flagged vessel on behalf of DG Shipping). Its purpose is to verify that the vessel strictly adheres to the national laws and international conventions ratified by that specific country. It is a scheduled, comprehensive inspection carried out annually.
PSI / PSC (Port State Inspection / Port State Control): This inspection is carried out by boarding officers representing a foreign coastal state (e.g., MMD surveyors boarding a foreign-flagged ship in Kolkata, or the USCG boarding a vessel in Houston). Its purpose is to verify that foreign ships visiting their domestic ports are fully compliant with international safety, manning, and environmental standards, ensuring they do not pose an active threat to local waters. PSC inspections can occur unannounced and are often driven by targeting matrices or deficiency history.