U.S. B-2 stealth bomber tests ACS 4.0 communication upgrade to boost secure global strike coordination.

On February 20, 2026, Sierra Nevada Corporation announced that its Adaptable Communications Suite 4.0 completed a first flight integrated on a Northrop B-2 Spirit as part of the aircraft’s modernization program.

On February 20, 2026, Sierra Nevada Corporation (SNC) announced that the U.S. Air Force had tested its Adaptable Communications Suite 4.0 (ACS 4.0) communications upgrade aboard a Northrop B-2 Spirit stealth bomber. The first flight confirms airborne integration of the new mission system computing environment as part of the B-2’s modernization program. The ACS 4.0 upgrade supports secure data exchange for long-range global strike missions conducted across joint command networks.
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The B-2 Spirit, an American strategic stealth bomber, entered service in 1997 to penetrate defended airspace while carrying conventional and nuclear payloads, and the U.S. Air Force plans to operate the 19 available B-2s until the early 2030s. (Picture source: U.S. Air Force)

Sierra Nevada Corporation (SNC) said its Adaptable Communications Suite 4.0 (ACS 4.0) completed a first successful flight integrated on the Northrop B-2 Spirit stealth bomber as part of the bomber’s modernization program. The flight confirms that the communications and mission-system computing upgrade has been installed and operated in airborne conditions. The integration was conducted in partnership with Northrop Grumman and is linked to efforts to align the B-2 with Combined Joint All-Domain Command and Control requirements. The milestone marks a transition from ground integration to flight validation, enabling additional operational testing. The objective is to support secure data exchange and interoperability across joint networks during long-range missions. The event represents a defined step in the phased upgrade of the B-2 fleet.

The Adaptable Communications Suite 4.0 provides a secure, open mission system computing environment designed to connect the aircraft to multiple military systems. The architecture supports interoperability within joint and combined command-and-control frameworks by enabling digital data exchange in real time. The open mission-system design allows software and hardware modules to be added or updated without structural redesign of the airframe. This configuration is intended to reduce integration time for future capabilities and to maintain compatibility with evolving network standards. The suite is integrated directly into the aircraft’s mission-system backbone rather than functioning as an external add-on. Its design emphasizes modularity and secure computing in contested electromagnetic environments.

The ACS 4.0 upgrade was developed and integrated by SNC in cooperation with Northrop Grumman under ongoing B-2 modernization efforts. The system is structured to enhance flexibility in how the bomber interfaces with communications links, mission computers, and other connected systems. It is intended to support both current operational requirements and incremental capability growth over time. The first-flight milestone permits further evaluation before fleet-wide deployment across operational squadrons. The upgrade forms part of a broader modernization path that includes avionics, radar, and mission-system updates conducted over the aircraft’s service life. The immediate focus of ACS 4.0 is communications and computing integration rather than aerodynamic or structural modification.

The B-2 Spirit, an American heavy strategic stealth bomber, entered operational service on January 1, 1997, following its first flight on July 17, 1989, and development under the Advanced Technology Bomber program initiated in 1979. A total of 21 aircraft were built between 1989 and 2000 after the originally planned procurement of 132 bombers was reduced following the end of the Cold War. Nineteen aircraft remain in active inventory after one crash in 2008 and another retirement following damage in 2022. The fleet is based primarily at Whiteman Air Force Base, Missouri, under the 509th Bomb Wing within Air Force Global Strike Command. The aircraft is scheduled for retirement no later than 2032 as the B-21 Raider enters service. The B-2 has been employed in Kosovo in 1999, Afghanistan and Iraq in the 2000s, Libya in 2011, Yemen in 2024, and strikes against Iranian nuclear facilities in 2025.

The aircraft measures 21.0 meters in length with a wingspan of 52.4 meters and a height of 5.18 meters, and it has a maximum takeoff weight of 170,600 kilograms. It is powered by four General Electric F118-GE-100 turbofan engines producing 77 kilonewtons of thrust each, mounted within the wing structure to reduce radar and infrared signatures. The B-2 has a service ceiling of 15,200 meters and a maximum speed of approximately 1,010 kilometers per hour at altitude. Its unrefueled range exceeds 11,000 kilometers and can be extended beyond 19,000 kilometers with aerial refueling. The crew consists of two personnel, a pilot and a mission commander, seated side by side. The flying wing configuration eliminates vertical stabilizers and contributes to reduced radar cross-section.

The B-2 carries ordnance internally in two weapons bays to preserve low observable characteristics. The official internal payload capacity is 18,000 kilograms, although operational loads have reached 27,000 kilograms in certain configurations. The aircraft can carry up to 80 GBU-38 500-pound class Joint Direct Attack Munitions or 16 GBU-31 2,000-pound class bombs on rotary launchers. It is certified to carry two 13,600-kilogram GBU-57 Massive Ordnance Penetrators for hardened underground targets. The B-2 also integrates AGM-158 Joint Air-to-Surface Standoff Missiles and has been configured for B61 and B83 nuclear bombs. Weapons are carried internally to maintain reduced radar visibility during penetration missions.

Program procurement cost averaged $929 million per aircraft in 1997 dollars, while total program cost including research, development, facilities, and support averaged $2.13 billion per aircraft. Total program expenditure reached $44.75 billion in 1997 dollars. Operating costs have historically required climate-controlled hangars to preserve radar-absorbent coatings and specialized maintenance procedures. The aircraft requires extensive servicing hours per flight hour compared with legacy bombers. Over time, the B-2 has received avionics upgrades, radar modifications, new computing architectures, and weapons integration improvements. The ACS 4.0 upgrade adds a communications and mission-system modernization layer intended to sustain network integration capability through the remaining operational lifespan of the fleet.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.