Still, with the arrival of the first donor 747 aircraft looking imminent, SNC is already taking important steps forward in crafting the successor to the E-4B Nightwatch 'doomsday plane.' ...

An E-4B Nightwatch airborne command post jet returned ... The aircraft are military versions of the Boeing 747-200, which are no longer flown for passenger use except by the Air Force.

and are set to succeed the service's aging Boeing 747-200-based E-4B Nightwatch ‘doomsday planes.’ SNC had been widely expected to win this deal after incumbent Boeing dropped out last year.