The USAF’s 55th Wing formally welcomed the second of three Boeing WC-135R Constant Phoenix atmospheric testing aircraft to its fleet on May 11, when the recently converted platform arrived at Offutt AFB in Nebraska.
This aircraft (serial 64-14831 ‘OF’) is the second of three former KC-135R Stratotankers to be modified to WC-135R-standard, as the USAF moves to replace its now retired WC-135C/W fleet. Initially delivered to the USAF in 1964, this aircraft was operated by the Arizona Air National Guard’s 161st Air Refueling Wing until it was selected for conversion from its previous tanker configuration to a new WC-135R.

The arrival of this aircraft at Offutt comes after the first converted WC-135R (serial 64-14836 ‘OF’) was delivered to the 55th Wing in July 2022 and recently deployed to RAF Mildenhall in Suffolk, UK – the type’s first operation outside the continental US – to undertake classified missions over Europe, likely related to the ongoing Ukraine War. The third and final WC-135R Constant Phoenix is scheduled to arrive at Offutt AFB in the autumn.
Operated by the 55th Wing’s 45th Reconnaissance Squadron (RS) and 21st Surveillance Squadron (Detachment 1), the WC-135R fleet is used to support US global atmospheric collection missions, where they detect and identify radioactive debris in the atmosphere – hence why the type is accurately nicknamed the ‘Nuke Sniffer’.
Commenting on the arrival of the second WC-135R, Lt Col Chris Crouch – commander of the 45th RS – said: “We’re really pleased about what ‘836’ has provided to us and very excited now to have a second jet. ‘831’ adds capability and eases our decision-making burden as far as balancing operations and training… We’re now able to go further with less support, which makes it easier to go to places we’ve never operated out of. These aircraft really expand our capabilities.”