Special Electronic Mission Aircraft
The RC-12 aircraft was first used as part of the US Army's Guardrail program. The special electronic mission aircraft (SEMA) used in the Guardrail system were initially based on the U-21 Ute aircraft, until transitioning to the C-12 Huron aircraft as part of the Improved Guardrail V program. The airframe includes navigation, avionics and survivability equipment. RC-12 and RC-12-like aircraft were then used for a wide array of programs requiring SEMA.
The RC-12D aircraft used in the Improved Guardrail V system were based on the King Air Model A200CT. This US Army Special Electronic Mission version carried the AN/USD-9 Improved Guardrail V remote-controlled communications intercept and direction-finding system. Other equipment included aircraft survivability equipment systems, the Carousel IV-E inertial navigation system, a TACAN system, radio datalink, the AN/ARW-83(V)5 airborne relay with antennas above and below wings, wingtip ELINT/COMINT pods. Associated ground equipment included the AN/TSQ-105(V)4 integrated processing facility, AN/ARM-63(V)4 AGE flightline van and AN/TSC-87 tactical commander's terminal. The system prime contractor was initially Electromagnetic Systems Laboratory, Inc (ESL), which subsequently became a part of TRW, with TRW eventually being acquired by Northrop-Grumman. The US Army had 13 RC-12Ds converted from C-12Ds, with deliveries starting in mid-1983. One aircraft was assigned to US Army Forces Command (FORSCOM) at Fort McPherson, Georgia, and the remainder to 1st Military Intelligence Battalion at Wiesbaden, Germany, and 2nd Military Intelligence Battalion at Stuttgart, Germany. The German-based aircraft were reassigned late 1991 to 3rd, 15th and 304th Military Intelligence Battalions at Camp Humphreys (South Korea), Fort Hood (Texas) and Fort Huachuca (Arizona) respectively. One was converted back to an earlier configuration as C-12D-1. Five new-build RC-12D-like aircraft were sold to Israel for 191 Squadron at Sde Dov. These aircraft were referred to either as RC-12D-FW or FWC-12D, with the FW reportedly being an abbreviation for "Field Wind," possibly a codeword for Israeli specific equipment fitted to the aircraft. The codeword "Big Apple" was also related to these aircraft.
The RC-12G, used for the Crazy Horse system, was a US Army Special Electronic Mission aircraft based on the King Air A200CT. Generally similar to RC-12D, the maximum takeoff weight was increased to 6,800 kilograms (15,000 pounds). The mission equipment contractor was Sanders Associates, Inc. Three RC-12G were delivered in 1985 after conversion from C-12D airframes. These aircraft served with the in Latin America and then with the 138th Military Intelligence Company (Aerial Exploitation) in Orlando, Florida, before being moved into storage at Fort Sill, Oklahoma.
The RC-12H aircraft used for Guardrail/Common Sensor System 3 (Minus) was a US Army Special Electronic Mission aircraft that was generally similar to the RC-12D, though with the maximum takeoff weight increased to 6,800 kilograms (15,000 pounds). The initial system contractor ESL Inc. delivered 6 in 1988 for the 3rd Military Intelligence Battalion at Camp Humphreys in Pyongtaek, South Korea.
The RC-12K aircraft used for Guardrail/Common Sensor System 4 was similar to RC-12H, but with a more powerful 1,100 shp PT6A-67 turboprop engine and a maximum takoff weight increased to 7,250 kilograms (16,000 pounds). The US Army ordered 9 in October 1985, of which 8 replaced RC-12Ds in 1st Military Intelligence Battalion in May 1991. One of these was subsequently lost in an accident. The ninth US Army aircraft was retained by the contractor, Raytheon, for conversion to the planned RC-12N configuration. An additional 2 RC-12K aircraft were delivered to Israel in May-June 1991.
The RC-12N aircraft used in Guardrail/Common Sensor System 1 was generally similar to the RC-12K, though with a 7,350 kilogram (16,200 pound) maximum takeoff weight, and equipped with dual EFIS and aircraft survivability equipment/avionics control system (ASE/ACS). The ASE suite included the AN/APR-39 radar warning receiver, AN/APR-44 radar warning system, AN/ALQ-136, AN/ALQ-156 and AN/ALQ-162 countermeasure sets chaff/flare and M130 dispensers. The avionics suite included AN/ARC-186 or AN/ARC-201 VHF-FM radio, AN/ARC-164 Have Quick II UHF-AM radio; AN/APX-100 IFF transponder; three KY-58 and one KIT-1A secure communications systems; Carousel IV INS; AN/ASN-149 GPS receiver. The prototype RC-12N was converted from an RC-12K. A total of 15 were converted by E-Systems and delivered 1992-93 to the 224th Military Intelligence Battalion at Hunter Army Air Field, Georgia and 304th Military Intelligence Battalion at Libby Army Air Force, Fort Huachuca, Arizona. One of these was lost in accident.
The RC-12P aircraft used in Guardrail/Common Sensor System 2 had the same avionics and power plant as the RC-12N, though with different mission equipment (including datalink capability), fibre optic cabling, and smaller and lighter wing pods. The maximum takeoff weight was increased to 7,480 kilograms (16,500 pounds). A total of 9 aircraft were delivered to ESL/TRW at Moffett Federal Airfield in late 1994 and 1995, and these airframes remained there in 1999.
The RC-12Q aircraft, referred to as the Direct Air Satellite Relay, consisted of 3 RC-12Ps modified by Raytheon and TRW to act as 'mother ships' to expand the RC-12P's operational area outside satellite 'footprints.' The airframes were transferred to TRW in 1996 for outfitting, where they remained in 1999. The aircraft featured a prominent dorsal radome housing a satellite communications antenna.
On 16 April 1997, the 224th Military Intelligence Battalion lost an RC-12N and 2 crewmembers in a fatal training accident. The following year on 6 November 1998, the 1st Military Intelligence Battalion lost a RC-12K and 2 crewmembers in a similar training accident. In both accidents, the United States Army Safety Center Accident Boards listed in their recommendations to TRADOC to 'Reevaluate the ATM Tasks for stalls, slow flight and VMC.' In February 1999, Commanding General, USAIC and FH, Major General John D. Thomas, sent a senior standardization instructor pilot and the 305th Military Intelligence Battalion Safety Officer to USAAVNC to review the RC-12K Accident Board findings to determine if training was a contributing factor. They recommended to Major General Thomas that the TC 1-219, Tasks for Slow Flight, Stalls and VMC, be rewritten.
The RC-12X aircraft was a further improved RC-12 for use with the GRCS, which included expanded frequency ranges, a capability to locate signals in both stand-off and stand-in modes, and an adaptive beam-forming antenna array that is capable of locating emitters in the dense signal environments.
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