Weapon Systems Officer

A weapon systems officer ("WSO", pronounced "wizzo") is an air flight officer directly involved in all air operations and weapon systems of an aircraft.

In the United States Navy, they are responsible for manning the weapon systems of a fighter. (In the U.S. Air Force and Marine Corps, "WSO" also refers to the aft crew member in the F-15E Strike Eagle, B-1 Lancer and F/A-18D Hornet.) The WSO integrates with the pilot to collectively achieve and maintain crew efficiency, situational awareness and mission effectiveness. In the U.S. Air Force fighter aircraft such as the F-15E Strike Eagle, the WSO can pilot the aircraft when required although this is typically during non-tactical portions of the mission (e.g., returning to base). When designated mission commander (MC), the WSO is also responsible for all phases of the assigned mission.

In the British Royal Air Force, a WSO (formerly navigator) is a commissioned officer that operates aircraft mission systems on the Tornado GR4 amongst other platforms. Non-Commissioned aircrew can serve as a WSOp (Weapon Systems Operator), an umbrella term for the various specialist aircrew responsible for assisting the pilot in operating the mission systems of the aircraft (e.g. linguists, loadmasters, crewman).