The Department of the Air Force awarded Sierra Nevada Corp. a $13 billion contract to replace the service’s aging E-4B Nightwatch “doomsday planes” for nuclear war. Sierra Nevada will develop the Survivable Airborne Operations Center to succeed the E-4B by July 10, 2036, with $59 million in initial funds.

The E-4B, used as the National Airborne Operations Center for nuclear war emergencies, has been flying since the 1970s and is reaching the end of its service life. Sierra Nevada will build SAOC in Colorado, Nevada, and Ohio, using a commercial derivative aircraft with modern secure communication systems.

The contract covers the delivery of engineering and manufacturing development aircraft, production aircraft, ground systems, trainers for aircrew, mission crew, and maintainers, and other support equipment. It includes cost-plus-incentive-fee, fixed price incentive, and cost-plus-fixed-fee components according to the Pentagon’s contract announcement.