OHIO— The US Air Force and Sierra Nevada Corporation (SNC) have begun flight tests of the next-generation E-4C Survivable Airborne Operations Center (SAOC). This aircraft, based on a heavily modified Boeing 747-8, is designed to ensure continued airborne command and control during national emergencies, including nuclear conflict.
The inaugural test flight occurred on August 7, 2025, at the Aviation Innovation and Technology Center in Dayton, Ohio, marking a critical step in replacing the aging E-4B Nightwatch fleet.
US Air Force One; Photo-redlegsfan21 Flickr; Wikimedia CommonsFlight Testing Underway
Sierra Nevada has initiated its first test flight, aiming to validate the E-4C’s core systems under operational conditions. The tests will assess the hardened aircraft’s resilience to electromagnetic pulses and radiation and evaluate its secure communications and mission systems.
Sierra Nevada received a $13 billion contract in April 2024 to convert up to five Boeing 747-8 airframes into SAOC aircraft.
Flight and ground testing will continue into 2026 at facilities in Dayton, Ohio, and Wichita, Kansas, as the company seeks to identify and resolve engineering challenges early in the program.
The campaign includes rigorous ground and flight assessments and will span key facilities through 2026.
Photo: Trump White House ArchiveReplacing an Aging Fleet
The E-4B Nightwatch aircraft, which have served since the 1970s, are nearing the end of their service lives and are technologically outdated.
The E-4C fleet is intended to succeed the E-4Bs, offering modernized capabilities in airborne command, control, and communications (NC3) under catastrophic conditions.
Here are a few specifications of the E-4B Nightwatch aircraft that the next-generation E-4C aircraft is set to replace:
| Primary function | Airborne operations center |
| Builder | Boeing Aerospace Co. |
| Power plant | Four General Electric CF6-50E2 turbofan engines |
| Thrust | 52,500 pounds each engine |
| Length | 231 feet, 4 inches (70.5 meters) |
| Wingspan | 195 feet, 8 inches (59.7 meters) |
| Height | 63 feet, 5 inches (19.3 meters) |
| Maximum takeoff weight | 800,000 pounds (360,000 kilograms) |
| Endurance | 12 hours (unrefueled) |
| Ceiling | Above 30,000 feet (9,091 meters) |
| Unit cost | $223.2 million (fiscal 98 constant dollars) |
Photo: USAF | Wikimedia Commons https://commons.wikimedia.org/wiki/File:E-4_landing.jpgProgram Scope and Timeline
The $13 billion SAOC contract covers development, modification, production, and support through 2036. SNC has already acquired four Boeing 747-8 aircraft and expects full delivery of aircraft by mid-2030s.
The company has expanded its infrastructure, adding multiple hangars at Dayton to support conversion and testing activities.
Bottom Line
The E-4C program forms a cornerstone of the United States’ NC3 modernization efforts. Its survivable airborne command capability ensures continuity of leadership and military control even if ground-based command centers are compromised.
This program underscores the critical role of resilient airborne infrastructure in national security strategy.
Boeing 747SP | Photo: NASAE-4C ‘Doomsday Plane’ FAQs
The E-4C is designed to function as a secure airborne command and control center during national emergencies, including nuclear conflict, ensuring continuity of government and military operations if ground-based facilities are compromised.
The E-4C, based on the Boeing 747-8, brings updated systems hardened against electromagnetic pulses, modernized communications, and extended mission endurance. The E-4B aircraft, in service since the 1970s, are nearing the end of their operational life and lack these advanced capabilities.
Flight and ground testing began in 2025 and will continue into 2026 at facilities in Dayton, Ohio, and Wichita, Kansas. Sierra Nevada Corporation will deliver the modified aircraft through the mid-2030s under a $13 billion contract, with full program support planned through 2036.
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