The US Air Force and aerospace firm Sierra Nevada Corp. (SNC) have started flight tests of America’s next-generation “doomsday plane.” The aircraft, officially called the E-4C Survivable Airborne Operations Center (SAOC), is designed to serve as a flying command center during catastrophic events like nuclear war.
Sierra Nevada confirmed that the first test flight took place on August 7, 2025, at the Aviation Innovation and Technology Center in Dayton, Ohio. These tests are part of the engineering and manufacturing development phase. More flight and ground testing will continue through 2026 in Dayton, Ohio, and Wichita, Kansas.
Purpose of the Doomsday Plane
The new SAOC will allow the US president and military leaders to direct forces and communicate from the sky if ground command centers are destroyed. The aircraft will replace the Air Force’s aging E-4B Nightwatch fleet, which has been in service for over 50 years.
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Sierra Nevada won a $13 billion contract in 2024 to build five SAOC aircraft. The company must finish the project by July 2036.
Built from Boeing 747-8 Jets
The SAOC aircraft are being made from heavily modified Boeing 747-8 planes. These jets are being hardened against radiation and electromagnetic pulses (EMPs). They will also feature secure communication antennas, advanced computers, and special mission systems.
The first 747-8 for SAOC arrived in Dayton in June 2024, just weeks after the contract was awarded. Since then, three more aircraft have arrived, with the fourth delivered in April 2025.
Modern Technology and Secure Systems
Sierra Nevada is using a modular open systems approach for the SAOC program. This method will make it easier to upgrade the aircraft with new secure communication systems and technologies in the future.
Lt. Gen. Daniel Caine earlier explained the importance of these systems, saying the aircraft must operate under the most extreme conditions with full coordination across multiple platforms.
Expansion at Dayton Airport
To meet the demands of this massive project, Sierra Nevada has been expanding its facilities. In October 2024, the company opened a second hangar at Dayton International Airport to convert 747-8 jets into SAOC aircraft. Construction has also started on two more hangars, with the first expected to open by October 2025.
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This is the largest single contract in Sierra Nevada’s 60-year history, and the company sees it as a gateway to more big defense opportunities.
Replacing the Old Fleet
The current E-4B aircraft, also known as the National Airborne Operations Center (NAOC), is more than half a century old. These planes are nearing the end of their service life, making the SAOC a critical replacement to keep America’s airborne command capability strong.
