The Air Force and aerospace firm Sierra Nevada Corp. have started flight tests on the service’s next-generation “doomsday plane.”
Flight tests for the E-4C Survivable Airborne Operations Control, or SAOC, are being held at the Aviation Innovation and Technology Center in Dayton, Ohio, the company said in a Wednesday release.
Sierra Nevada, also known as SNC, carried out the SAOC’s first flight on Aug. 7 as part of the program’s engineering and manufacturing development process. Flight and ground testing will continue into 2026, primarily in Dayton, Ohio, and Wichita, Kansas, the company said.
SAOC is meant to serve as an airborne command-and-control center that would be used in the most catastrophic circumstances. In the event of a nuclear war or other widespread calamity that destroys or disrupts most military command centers, the SAOC would allow the president to direct U.S. forces and relay orders from the air.
The Air Force in 2024 awarded SNC a $13 billion contract to build five SAOC aircraft to replace the Air Force’s aging fleet of four E-4B Nightwatch planes. Sierra Nevada is expected to finish the work by July 2036.
Sierra Nevada said these flight tests are meant to help reduce risks early in SAOC’s development process by identifying problems before they become worse down the line and cause delays.
The planes are being built from heavily modified Boeing 747-8 aircraft. Sierra Nevada is hardening the planes to protect against radiation and electromagnetic pulses, as well as adding communication antennas, computers and mission systems.
The first 747-8 earmarked for SAOC arrived at Sierra Nevada’s innovation and technology center at Dayton International Airport in June 2024, about a month and a half after the contract was awarded. Three more 747-8s have followed, with the fourth having arrived in April 2025.
Sierra Nevada plans to use a modular open system approach, with modern secure communication systems, to build SAOC
The SAOC deal is Sierra Nevada’s largest single contract in its six-decade history, and the company hopes it will lead to more big-ticket opportunities.
Sierra Nevada is expanding for this work as well. In October 2024, the company opened a second hangar to convert a 747 into SAOC at the Dayton airport and broke ground on two more hangars there. The first of those new hangars is expected to be finished and open for operations in October 2025, the company said.
The current fleet of E-4Bs, officially called the National Airborne Operations Center, is more than half a century old and the planes are near the end of their service lives.
Stephen Losey is the air warfare reporter for Defense News. He previously covered leadership and personnel issues at Air Force Times, and the Pentagon, special operations and air warfare at Military.com. He has traveled to the Middle East to cover U.S. Air Force operations.