In U.S. Naval Aviation (USN & USMC), when designated as the mission commander (MC), the WSO is responsible for all phases of the assigned mission, especially if there are multiple aircraft involved. For example, the aircraft pilot could be the junior member of a flight crew such as a USN lieutenant, junior grade/USMC 1st lieutenant or USN lieutenant/USMC captain, and the weapon systems officer could be a senior officer such as a USN lieutenant commander, commander or captain, or a USMC major, lieutenant colonel, or colonel; this would likely make the WSO the mission commander.