The United States Air Force operates many specialty aircraft that provide airborne-monitoring systems. Among the more specialized planes is the WC-135W "Constant Phoenix" atmospheric collection aircraft, which serves as an aerial collection platform for the detection and identification of debris from nuclear weapons detonations. It has earned the nicknames "weather bird" and, more commonly, "the sniffer."

The aircraft, which is based on a modified C-135B Stratolifter, is controlled by the Air Force Technical Applications Center and operated by the 45th Reconnaissance Wing at Offutt Air Force Base in Nebraska.

In recent days, the aircraft was reportedly seen over Scotland and heading towards Norway. It was likely conducting patrol flights that began after Russian president Vladimir Putin put his nation's nuclear arsenal on alert following the unprovoked Russian invasion of Ukraine.

Forward Deployment

The Constant Phoenix was deployed to Royal Air Force Mildenhall air base in late January as Russia continued to mass its forces along the Ukrainian border.

This deployment of the sniffer to Europe is unique.

Following the 1986 Chernobyl nuclear plant disaster in 1986, multiple WC-135s were sent to monitor the catastrophe, but since then the sniffer has only been sent to Europe twice. The first deployment was in 2017 while the second was in 2020, and both deployments took it close to Russian airspace.

Last of the Current Sniffers

The Constant Phoenix, now based out of the UK, is actually the last of ten WC-135Bs—plus one converted from a former EC-135C—still in service. It has continued to collect particulate and gaseous effluents and debris from accessible regions of the atmosphere in support of the Limited Nuclear Test Ban Treaty of 1963.

The aircraft's modifications are primarily related to its on-board atmospheric collection suite, which allows the mission crew to detect radioactive "clouds" in real time. It is also equipped with external flow-through devices to collect particulates on filter paper and a compressor system for whole air samples collected in holding spheres.

The cockpit crew is from the 45th Reconnaissance Squadron at Offutt Air Force Base, Nebraska, and special equipment operators are assigned to Det. 1, Air Force Technical Applications Center at Offutt Air Force Base.

Despite the fact that only a single Constant Phoenix remains in operational service, it is the only platform in the U.S. Air Force's inventory designed to conduct air-sampling operations. Until recently, there had been two WC-135Bs that were regularly deployed to the Pacific Ocean, where they were used to help keep track of the progress of North Korea’s nuclear program.

It is unclear if the aircraft is also monitoring for any radiation leaks at the Chernobyl nuclear plant, which was captured this week by Russian forces.

As part of the Department of Defense's fiscal year 2019 budget, three KC-13Rs will be converted to WC-135Rs, allowing for the retirement of the aging aircraft—yet the Constant Phoenix program will remain a constant.

Peter Suciu is a Michigan-based writer who has contributed to more than four dozen magazines, newspapers and websites. He regularly writes about military small arms, and is the author of several books on military headgear including A Gallery of Military Headdress, which is available on Amazon.com.

Image: Reuters.