Sierra Nevada’s E-4C ‘Doomsday Plane’ Begins Flight Testing for U.S. Air Force

Sierra Nevada Corporation (SNC) has achieved a major milestone in the E-4C Survivable Airborne Operations Center (SAOC) program, with the first flight test of the aircraft taking place on August 7, 2025 in Dayton, Ohio. This test marks the beginning of an extensive flight trial campaign that will establish a technical baseline before full conversion into an advanced airborne command post.

New Era of Strategic Air Command

The E-4C is designed to replace the aging E-4B Nightwatch fleet, which has served since the 1970s as the “doomsday plane.” These aircraft act as airborne command centers for the U.S. President, Secretary of Defense, and senior military leaders in the event of a nuclear conflict or national crisis. The new E-4C will bring greater survivability, modern communications, and nuclear and electromagnetic hardening, ensuring mission continuity well into the mid-21st century.

Aircraft Origins and Fleet Development

At present, four Boeing 747-8i aircraft—purchased from Korean Air—are at SNC’s Dayton facility undergoing modification. A total of five airframes have been acquired so far, with the contract allowing for up to eight conversions. These modern 747-8i jets will be heavily rebuilt, fitted with advanced command, control, and communications suites, aerial refueling systems, and hardened structures to withstand extreme conditions.

Contract and Delivery Timeline

The U.S. Department of Defense awarded SNC a $13.1 billion contract in April 2024 to develop and deliver the SAOC fleet. The program’s first stage includes conversion of two aircraft, with deliveries scheduled to run through July 2036. The initial flight testing phase will continue into 2026, focusing on reducing risks and validating the design before mission-specific modifications begin.

Industry Partnerships and Infrastructure

SNC is leading the program with support from major partners, including Collins Aerospace, GE Aerospace, Lockheed Martin Skunk Works, NIAR, and Rolls-Royce. To meet the demands of the project, SNC has expanded its facilities in Dayton, opening new hangars and planning additional infrastructure to handle the scale of conversions.

A Vital National Mission

The E-4C SAOC is more than just a replacement aircraft; it is a cornerstone of America’s nuclear command and control strategy. The modernization ensures that the U.S. will continue to have a secure and survivable airborne command capability in the face of evolving global threats. Full operational capability is expected in the early to mid-2030s.