Frigate lieutenant

Frigate lieutenant is a rank in some navies, especially those of Spain (Spanish: Alférez de Navío) and Latin America, roughly equivalent to a sub-lieutenant in the Royal Navy or a lieutenant (junior grade) in the US Navy. The French Navy equivalent is a ship-of-the-line ensign (first class) (French: enseigne de vaisseau de première classe).

The NATO rank code is OF-1 (senior)