Lieutenant commander
Lieutenant commander (LCDR or Lt. Cmdr.) is a Junior Officer rank in the United States Navy, the United States Coast Guard, the United States Public Health Service Commissioned Corps, and the National Oceanic and Atmospheric Administration Commissioned Officer Corps (NOAA Corps), with the pay grade of O-4 and NATO rank code OF-3. When introducing a lieutenant commander their full rank should always be used; however, in general conversation they are usually called "commander" even though they are not a "full" commander (which is one rank higher). Never use just "lieutenant" because it is one rank lower. The predecessors of the NOAA Corps, the United States Coast and Geodetic Survey Corps (1917–1965) and the Environmental Science Services Administration Corps (1965–1970), also used the lieutenant commander rank, and the rank is also used in the United States Maritime Service and the United States Naval Sea Cadet Corps. Lieutenant commanders rank above lieutenants and below commanders, and rank is equivalent to a major in the United States Army, United States Air Force, and United States Marine Corps.