The US Air Force’s (USAF) B-21 Raider was spotted refueling mid-air for what appears to be the first time, marking a key milestone toward the first aircraft’s scheduled 2027 delivery.
Open-source intelligence accounts and photographers took to social media to share images and videos of a B-21 flying in proximity to a KC-135 Stratotanker, while being escorted by an F-16 fighter jet over California.
An unnamed USAF spokesperson later confirmed to Defense One that the long-range stealth strategic bomber, developed by Northrop Grumman, is indeed undergoing key refueling tests as part of validating the aircraft’s capabilities and operational readiness.
Last month, Northrop and the USAF announced that they are accelerating B-21 production, signaling that the bomber might be delivered sooner than planned.
Aerial Refueling
Aerial refuelling tests typically come before weapons integration and operational test and evaluation, before an aircraft reaches initial operational capability or is declared officially combat-ready.
“When you have a new aircraft, you do proximity testing, you approach the refueling envelope, and you do that multiple times,” said Mark Gunzinger, a former B-52 bomber pilot and the Director of Future Concepts and Capability Assessments at the Mitchell Institute.
After proximity testing, the aircraft practices emergency breakaways, as well as connecting and disconnecting from the tanker’s refueling boom.
Once pilots are confident and all systems are ready, they actually pass fuel from the tanker to the aircraft, Gunzinger explained.
B-21 Progress
Unveiled in December 2022, the stealth B-21 Raider can carry and deploy both conventional and nuclear weapons against high-value, deeply defended targets, including advanced air defense systems, naval combatants, and ground sites.
It completed its maiden flight in November 2023, with Northrop Grumman cleared for the aircraft’s low-rate production shortly after.
The USAF officially aims to acquire a minimum of around 100 B-21s, which will incrementally replace the B-1 and B-2 bombers in the inventory, although analysts have recommended at least doubling the quantity to effectively counter US adversaries.
