The deployment of a Constant Phoenix in Europe is quite unusual. During the 1986 Chernobyl nuclear power plant accident, the first incidence occurred when many WC-135s were dispatched to monitor the tragedy. Since then, the sniffer has only made two trips to the continent: once in 2017 and once in 2020.
Previously, air sampling missions were routinely conducted over the Far East, the Indian Ocean, Bay of Bengal, Mediterranean Sea, the Polar regions, and off the coasts of South America and Africa.
More notably, back in
2017, an aircraft was deployed to RAF Mildenhall to conduct missions over
Europe after air quality stations detected traces of radioactive Iodine-131.
What is the WC-135W
Aircraft?
The WC-135 ‘Constant
Phoenix’ is the U.S. Air Force, a special-purpose aircraft derived from the
Boeing C-135 Stratolifter (as well as the RC-135 ‘Rivet Joint’ signals
intelligence aircraft used by the Royal Air Force). According to the U.S. Air
Force, its mission is to collect samples from the atmosphere to detect and
identify nuclear explosions.
The aircraft is
outfitted with external flow-through devices for collecting particles on filter
paper and a compressor system for collecting full air samples in holding
spheres. The WC-135 is based on the C-135 Stratolifter’s airframe. Only two of
the 10 WC-135 aircraft manufactured (plus one EC-135C modified in 1998) remain
in service, with the USAF 45th Reconnaissance Squadron. They are both
frequently requested in the Pacific Ocean to watch North Korea’s nuclear
development. The WC-135W’s current
mission in Europe is unknown.