TYB
Sneaky! Sneaky! Constant Phoenix!
Call sign JAKE21. Usually these flights use ATOM call sign. Squawk 1250. Offutt nased USAF WC-135 Constant Phoenix 64-14836 out of RAF Mildenhall. Flew high altitude over France and Italy. Then dropped down to 5,000 feet about 100 miles east of Malta and flew toward Israel. Now has climbed back up to 15,000 feet.
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The WC-135 Constant Phoenix is a special-purpose aircraft derived from the Boeing C-135 Stratolifter and used by the United States Air Force. Its mission is to collect samples from the atmosphere for the purpose of detecting and identifying nuclear explosions. It is also informally referred to as the "weather bird" or "the sniffer" by workers on the program and international media respectively.
https://en.wikipedia.org/wiki/Boeing_WC-135_Constant_Phoenix