Boeing WC-135 Constant Phoenix

The WC-135 Constant Phoenix is a special purpose aircraft derived from the Boeing C-135 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.

Role Atmosphere Testing Related to Nuclear Incidents
Manufacturer Boeing Military Airplanes Division
Introduction December 1965
Primary user United States Air Force
Number built 10 original WC-135B, plus 1 converted former EC-135C (2 still in service)
Developed from C-135 Stratolifter
Variants OC-135B Open Skies

The WC-135W (tail number 61-2667) is a modified C-135B. The WC-135C (tail number 62-3582) is an extensively modified former EC-135C Looking Glass aircraft. The Constant Phoenix’s modifications are primarily related to the aircraft's on-board atmospheric collection suite, which allows the mission crew to detect radioactive debris "clouds" in real time. The aircraft is equipped with external flow-through devices to collect particulates on filter paper and a compressor system for whole air samples collected in high-pressure holding spheres.

The interior seats 33 people, including the cockpit crew, maintenance personnel, and special equipment operators from the Air Force Technical Applications Center. On operational sorties, the crew is minimized to just pilots, navigator, and special equipment operators, to reduce radiation exposure to mission-essential personnel only.


General characteristics

  • Crew: varies with mission
  • Length: 139 ft 11 in (42.6 m)
  • Wingspan: 130 ft 10 in (39.9 m)
  • Height: 42 ft (12.8 m)
  • Wing area: 2,433 ft² (226 m²)
  • Max. takeoff weight: 300,500 lb (136,300 kg)
  • Powerplant: 4 × Pratt & Whitney TF33-P-9 turbofan with thrust reversers, 16,050 lbf (71.4 kN) each


  • Maximum speed: 350 knots (648 km/h)
  • Range: 4000 miles (6437 km)
  • Service ceiling: 40,000 ft (12,200 m)
  • Wing loading: 123.5 lb/ft² (603 kg/m²)
  • Thrust/weight: 0.21


  • None


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