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The OC-135B Open Skies is a United States Air Force
observation aircraft A surveillance aircraft is an aircraft used for surveillance. They are operated by military forces and other government agencies in roles such as intelligence gathering, battlefield surveillance, airspace surveillance, reconnaissance, observat ...
that supports the
Treaty on Open Skies The Treaty on Open Skies 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 ...
. The aircraft, a modified WC-135B, flies unarmed observation flights over participating parties of the treaty. Three OC-135B aircraft were modified by the Aeronautical Systems Center's 4950th Test Wing at
Wright-Patterson Air Force Base Wright-Patterson Air Force Base (WPAFB) is a United States Air Force base and census-designated place just east of Dayton, Ohio, in Greene and Montgomery counties. It includes both Wright and Patterson Fields, which were originally Wilbur W ...
in Ohio. The first operationally-capable OC-135B was assigned to the
24th Reconnaissance Squadron The 24th Expeditionary Reconnaissance Squadron is a provisional unit of the United States Air Force. It is assigned to United States Air Forces Europe to activate or inactivate as needed. Its last known attachment was to the 100th Air Refue ...
at
Offutt AFB Offutt Air Force Base is a U.S. Air Force base south of Omaha, adjacent to Bellevue in Sarpy County, Nebraska. It is the headquarters of the U.S. Strategic Command (USSTRATCOM), the 557th Weather Wing, and the 55th Wing (55 WG) of the Air ...
in October 1993. It is now fitted with a basic set of navigational and sensor equipment, and was placed in inviolate storage at the
Aerospace Maintenance and Regeneration Center The 309th Aerospace Maintenance and Regeneration Group (309th AMARG),Offici ...
at Davis-Monthan Air Force Base near Tucson, Arizona in 1997. Two fully operational OC-135B aircraft were delivered in 1996 with the full complement of treaty-allowed sensors, which includes an infrared line scanner, synthetic aperture radar and video scanning sensors. In May 2020, the Trump administration said it would exit the treaty and gave the required six-month notice. In November, it announced plans to liquidate the two 60-year-old jets, offering them to other countries.


Description of aircraft

The interior seats 35 people, including the cockpit crew, aircraft maintenance crew, foreign country representatives and crew members from the U.S. Department of Defense's Defense Threat Reduction Agency (DTRA). Cameras installed include one vertical and two oblique KS-87E framing cameras used for low-altitude photography approximately 3,000 feet (900 m) above the ground, and one KA-91C panoramic camera, which scans from side to side to provide a wide sweep for each picture used for high-altitude photography at approximately . The data annotation and recording system (DARMS) processes navigational, altitude, time and camera signals to annotate each picture with correct position, altitude, time, roll angle and other information. In addition, this system records every picture taken according to camera, frame and navigational position. A keyboard with trackball is the input device for operation of this system. Two Barco
VGA Video Graphics Array (VGA) is a video display controller and accompanying de facto graphics standard, first introduced with the IBM PS/2 line of computers in 1987, which became ubiquitous in the PC industry within three years. The term can now ...
color monitors display camera annotation and other camera data on screen for the sensor operator and observer use. Camera control, located in the sensor operator's console, operates and adjusts individual cameras for cloud cover, frame overlap and other functions. The sensor operator console seats four and has all the equipment listed above plus camera bay heating control, chronometers, emergency oxygen, interphone and individual lighting. The flight following console also seats four and includes most of the equipment listed above except for DARMS and camera controls. Seven commercial Norcold Tek II coolers with individual refrigeration units maintain temperature and humidity control to maintain peak film performance. The units can be removed, if necessary, from the aircraft in order to transport film. The coolers are capable of storing of film.


Flight path

The aircraft flies on its intended flight path throughout the entire mission with no reliance on ground-based navigation devices. A top-of-the-line commercial system, Litton 92 INS/GPS, which is an integrated inertial navigation system (INS) with a
global positioning system The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sys ...
(GPS), provides continuous updates. The GPS updates the INS several times per second to correct any deviations in the flight path. The INS also feeds precise latitude, longitude, time, roll angle and barometric altitude to the DARMS and camera systems. A true airspeed computer feeds true airspeed data to the INS. A combined altitude radar altimeter provides precise height above ground information to the pilot for navigational purposes as well as a signal to DARMS for film annotation. It is accurate from above the ground level. Plus, a metric altimeter is installed on the pilot's instrument panel for altitude reference when flying in countries that use meters for altitude reference. The aircraft are being upgraded with the Block 30 Pacer Crag Navigational System upgrade, a first step in making them compliant with ICAO mandated
Global Air Traffic Management {{Unreferenced, date=December 2009 Global air-traffic management (GATM) is a concept for satellite-based Communication, navigation and surveillance and air traffic management. The Federal Aviation Administration and the International Civil Aviation ...
and
Global Air Navigation Standards Global means of or referring to a globe and may also refer to: Entertainment * ''Global'' (Paul van Dyk album), 2003 * ''Global'' (Bunji Garlin album), 2007 * ''Global'' (Humanoid album), 1989 * ''Global'' (Todd Rundgren album), 2015 * Bruno ...
guidelines.


Modifications

The OC-135B modifications center around four cameras installed in the rear of the aircraft. Since its primary mission is to take pictures, most of the installed equipment and systems provide direct support to the cameras and the camera operator. Other modifications to the aircraft also included installing an auxiliary power unit, crew luggage compartment, sensor operator console, flight following console and upgraded avionics. Though the aircraft feature a large window in the cargo door, this is simply a remnant of their previous weather reconnaissance role. Other modifications support the aircrew. A gaseous oxygen system replaced the liquid oxygen system to be more compatible with foreign airfields, and fluorescent lighting system was added throughout the cabin to provide adequate lighting for operation and inspections. Four upgraded seats with a conference table, interphone, lighting and oxygen comprise the mission commanders' station for both countries' mission commanders. A four channel interphone system enables segregated communications between various elements on board. The auxiliary power unit enables the aircraft to start engines and provides electrical power and cabin heat independent of ground support equipment. It was manufactured by
Allied Signal AlliedSignal was an American aerospace, automotive and engineering company created through the 1985 merger of Allied Corp. and Signal Companies. It subsequently purchased Honeywell for $14.8 billion in 1999, and thereafter adopted the Honeywell n ...
with the installation and design of the installation by E-Systems and World Auxiliary Power Company. The aircraft are assigned to Air Combat Command at the
55th Wing The 55th Wing is a United States Air Force unit assigned to Air Combat Command. The wing is primarily stationed at Offutt Air Force Base, Nebraska, but maintains one of its groups and associated squadrons at Davis-Monthan Air Force Base, Ariz ...
,
45th Reconnaissance Squadron The 45th Reconnaissance Squadron is a United States Air Force unit. It is assigned to the 55th Operations Group and stationed at Offutt Air Force Base, Nebraska. It is one of the most decorated squadrons of the active duty United States Air ...
, Offutt Air Force Base near Omaha, Nebraska, for operations, training and maintenance. When tasked, ACC's role is to transport a DTRA observation team to an Open Skies point of entry airport, conduct the observation flight, and then return the team to the continental United States.


Specifications (OC-135)


See also


References

This article includes public domain text from the following United States Government source:
OC-135B Fact Sheet
published by the
Air Combat Command Air Combat Command (ACC) is one of nine Major Commands (MAJCOMs) in the United States Air Force, reporting to Headquarters, United States Air Force (HAF) at the Pentagon. It is the primary provider of air combat forces for the Air Force, and i ...
{{DEFAULTSORT:OC-135B Open Skies C-0135OB Open Skies
Boeing OC-135B Open Skies The OC-135B Open Skies is a United States Air Force observation aircraft that supports the Treaty on Open Skies. The aircraft, a modified WC-135B, flies unarmed observation flights over participating parties of the treaty. Three OC-135B aircr ...
Quadjets Synthetic aperture radar Low-wing aircraft