Petty officer third class is the fourth enlisted rank in the U.S. Navy, U.S. Coast Guard, and the United States Naval Sea Cadet Corps, just above seaman and below petty officer second class, and is the lowest rank of non-commissioned officer, equivalent to a corporal in the U.S. Army and Marine Corps. Petty officer third class shares the same pay grade as senior airman in the Air Force, which no longer has an NCO rank corresponding with E-4.