A landing signal officer and his backup each hold up a pickle switch, ready to signal a waveoff to the pilot of an aircraft approaching the nuclear-powered aircraft carrier USS DWIGHT D. EISENHOWER (CVN 69)

Aircraft carriers are warships that act as airbases for carrier-based aircraft. In the United States Navy, these consist of ships commissioned with hull classification symbols CV (aircraft carrier), CVA (attack aircraft carrier), CVB (large aircraft carrier), CVL (light aircraft carrier), CVN (aircraft carrier (nuclear propulsion) and CVAN (attack aircraft carrier (nuclear propulsion). The first aircraft carrier commissioned into the United States Navy was USS Langley (CV-1) on 20 March 1922.