page_title: Treaty on Open Skies
section_title: Aircraft
hierarchical_section_title: Treaty on Open Skies / Basic elements of the treaty / Aircraft
caption_attribution_description: Русский: Ан-30 Украинских ВВС
context_page_description: The Treaty on Open Skies entered into force on January 1, 2002, and currently has 35 party states. It establishes a program of unarmed aerial surveillance flights over the entire territory of its participants. The treaty is designed to enhance mutual understanding and confidence by giving all participants, regardless of size, a direct role in gathering information about military forces and activities of concern to them. Open Skies is one of the most wide-ranging international efforts to date promoting openness and transparency of military forces and activities. The concept of "mutual aerial observation" was initially proposed to Soviet Premier Nikolai Bulganin at the Geneva Conference of 1955 by President Dwight D. Eisenhower; however, the Soviets promptly rejected the concept and it lay dormant for several years. The treaty was eventually signed as an initiative of U.S. president George H. W. Bush in 1989. Negotiated by the then-members of NATO and the Warsaw Pact, the agreement was signed in Helsinki, Finland, on March 24, 1992.
  This treaty is not related to civil-aviation open skies agreements.
context_section_description: Observation aircraft may be provided by either the observing party or by the observed party (the "taxi option"), at the latter's choice. All Open Skies aircraft and sensors must pass specific certification and pre-flight inspection procedures to ensure that they are compliant with treaty standards. 
  The official certified U.S. Open Skies aircraft is the OC-135B Open Skies.
  Canada uses a C-130 Hercules aircraft equipped with a "SAMSON" sensor pod to conduct flights over other treaty nations. The pod is a converted CC-130 fuel tank modified to carry the permitted sensors, along with associated on-board mission systems. A consortium of nations consisting of Belgium, Netherlands, Luxembourg, Canada, France, Greece, Italy, Portugal and Spain own and operate this system. The costs of maintaining the SAMSON Pod are shared, based on each nation's flight quota and actual use.
  Bulgaria, Romania, Russia and Ukraine use the Antonov An-30 for their flights. The Czech Republic also used to use the An-30 for this purpose but apparently retired all of theirs from service in 2003.
  Russia also uses a Tu-154M-ON monitoring aircraft. Germany formerly used this type as well until the aircraft was lost in a 1997 accident. Russia is phasing out both An-30 and Tu-154M-ON and replacing them with two Tu-214ON with the registrations RA-64519 and RA-64525. This aircraft's new sensor suite, though, is being challenged by the US.
  Sweden uses a Saab 340 aircraft ("OS-100") that was certified in 2004.
  Until 2008, the UK designated aircraft was an Andover C.1(PR) aircraft, registration XS596. Since then the UK has used a variety of aircraft including a Saab 340, an An-30 and an OC-135.
  In 2017, the German Air Force purchased an Airbus A319 as its future Open Skies aircraft.
caption: An-30 monitoring aircraft
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