As Wikipedia says:
“Commander (commonly abbreviated as Cmdr.) is a common naval officer rank as well as a job title in many armies. Commander is also used as a rank or title in other formal organizations, including several police forces. In several countries this naval rank is termed frigate captain.
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Commander is a rank used in navies, but is very rarely used as a rank in armies. In most armies, the term “commander” is used only as a job title like “platoon commander”, “brigade commander” and “squadron commander”.
Actually, Naval Commander (Royal Navy, US Navy) is equal to Lieutenant colonel (Army) and Captain 2nd rank (Soviet/Russian Naval Fleet).
Captain 2nd rank is the commander of a ship of the same rank: large amphibious, missile and destroyers. BUT, as you know, Sark’s ship is an entire aircraft carrier. That’s a 1st rank ship so Sark cannot command there as his rank would be too low for that. The ship is commanded by the 1st rank senior officer (captain 1st rank).
An aircraft carrier is a large surface ship of special purpose designed to provide air cover for the connection of ships, the landing of amphibious forces, air strikes on the connection of ships and individual enemy ships, on its coastal coastal defense, as well as for the transportation of goods and people, communication between the ships of the connection. Equipped with means to ensure the basing and functioning of aircraft. The main armament of an aircraft carrier is deck-based aircraft and helicopters (in case of the classic Grid - recognizers).
So Sark’s status of a Commander might be just a job title but not the real rank.
