The flight of a special plane from US Air Force (USAF) along the Brazilian coast was among the most tracked by the site Flightradar24 on the night of this Monday (16). The WC-135R Constant Phoenix aircraft is used to collect particles from the atmosphere in case of explosions or nuclear accidents. 

Operating with radio code MILLR36, the aircraft took off from San Juan, Puerto Rico, and continued flying along the South American coast. Upon arriving at the height of the state of Rio de Janeiro, the WC-135 descended to 6500 feet. The aircraft then turned around and began to return north.

It was at that moment that the WC-135 became the most followed by the site's users. Flightradar24. The flight can be accompanied by clicking here or by the plugin below. 

So far, the reasons for the presence of the US military aircraft in Brazilian airspace are unknown. Portal Aeroflap contacted the Brazilian Air Force and the 55th Wing of the USAF, which operates the WC-135, and is awaiting a response from the institutions. 

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Nuclear Sniffer

Based on the KC-135R Stratotanker tanker platform, the Boeing WC-135R registration 64-14836 was delivered to the US Air Force in June last year, replacing older versions of the model. 

Nicknamed Nuclear/Nuke Sniffer (Nuclear Sniffer), the jet is the result of the Constant Phoenix program, originated in 1947. The first WC-135 entered into operation in 1965, replacing the WB-50 (a version of the B-29 bomber) with the 55th Meteorological Reconnaissance Squadron. 

The aircraft's mission is quite specific: to detect radioactive particles present in the atmosphere. The USAF says the WC-135 “supports national level customers by collecting particulate and gaseous effluents and debris from accessible regions of the atmosphere in support of the 1963 Limited Nuclear Test Ban Treaty.” That's why his presence always draws attention wherever he goes. 

They are currently operated by the 45th Reconnaissance Squadron, subordinate to the 55th Wing at Offutt Air Force Base, in the state of Nebraska. The unit also operates RC-135 Rivet Joint spy planes.