The back seater is not a "copilot" :doh: . He's a Weapons System Operator (WSO - pronounced WIZZO). They are navigators.
The pilot (aircraft commander) can control and operate all of the sensors and systems that the WSO can and then some. However, it doesn't work that way. The workload is divided as needed w/the pilot flying the airplane, using the radar, looking for threats, pickle the weapons, and so on. The WSO will operate the mission sensors and coordinate the attack.
If this was what you were wondering :smartass::D