Signals intelligence collection, aircraft-based
An aircraft or unmanned aerial vehicle carrying SIGINT sensors is a SIGINT aircraft-based platform. A wide range of aircraft were used with low-tech aircraft such as the WWII [B-24] with temporarily mounted electronics, to platforms extensively modified for the mission, and evolved to strategic RC-135 RIVET JOINT (COMINT), RC-135 COMBAT SENT (ELINT) and EP-3E Aries II aircraft.
One strong trend is to put SIGINT sensors on unmanned aerial vehicles (UAV) as well as manned aircraft. Some intermediate versions of this trend already are present; the U.S. RC-12 GUARDRAIL system uses sets of three piloted aircraft and a ground station. The aircraft, however, only have a flight crew, and no onboard personnel or equipment to do SIGINT analysis.
- 1 Argentina: Aircraft Platforms
- 2 Australia: Aircraft Platforms
- 3 Chile: Aircraft Platforms
- 4 China: Aircraft Platforms
- 5 France: Aircraft Platforms
- 6 Germany: Aircraft Platforms
- 7 Israel: Aircraft Platforms
- 8 India: Aircraft Platforms
- 9 Mexico: Aircraft Platforms
- 10 Russia: Aircraft Platforms
- 11 Saudi Arabia: Aircraft Platforms
- 12 South Africa: Aircraft Platforms
- 13 Spain: Aircraft Platforms
- 14 Sweden: Aircraft Platforms
- 15 Turkey: Aircraft Platforms
- 16 United Kingdom: Aircraft Platforms
- 17 United States: Aircraft Platforms
- 18 References
Argentina: Aircraft Platforms
After its experience in the Falklands, Argentina had a 707 converted to an ELINT aircraft by Israel.
Australia: Aircraft Platforms
Chile: Aircraft Platforms
Chile has a full Israeli Phalcon system on a single 707 airframe. This system provides SIGINT as well as airborne radar warning and control.
China: Aircraft Platforms
Prof. Desmont Ball identified Chinese the first major airborne SIGINT platforms as the four-turboprop EY-8, a variant of the Russian An-12 'Cub' as China's main ELINT and reconnaissance aircraft a decade ago. EY-8 construction may be continuing for ELINT/SIGINT and electronic warfare missions. This capability, however, is much inferior to the Japanese equivalents. . They were supplemented or replaced four locally modified Tu-154Ms, comparable to the Russian 1980s vintage Il-20 ELINT aircraft.
France: Aircraft Platforms
France operates the C-160 aircraft twin-turboprop tactical transport, due to be replaced by the C-160 by the Airbus Military A400M transport when that enters service from 2009. The French Air Force planned to begin retiring its fleet of C-160 transports in 2005. Gabriel SIGINT versions of the Transall are an upgraded electronic surveillance version in service with the French Air Force, which also operates four Astarte strategic communications relay versions. Thales developed the signals intelligence (SIGINT) system for which there are 10 workstations in the main cabin. C-160 fleets of France, Germany and Turkey will be replaced by the Airbus Military A400M transport when that enters service from 2009. The French Air Force will begin retiring its fleet of C-160 transports in 2005.
Originally manufactured by the companies MBB, Nord Aviation and VFW formed the Transall group in 1959 for the development and production of the C-160 for the air forces of France, Germany, South Africa and Turkey. Production of the aircraft by the three companies ended in 1972, with 169 aircraft having been delivered. In 1976, responsibility for production of the aircraft was given to Aerospatiale in France and MBB (now DaimlerChrysler Aerospace) in Germany. Both companies are now part of EADS (European Aeronautics Defence and Space). Production of the aircraft from 1976 to 1985 included updated avionics, a reinforced wing housing and additional fuel tanks.
French Transalls were upgraded in 1999, with a new head-up display and an upgraded electronic warfare suite, with a radar warning receiver, missile approach warner and chaff and decoy dispensers. Navigational systems include EFIS 854 TF Electronic Flight Instrumentation System, which includes an Electronic Attitude Director Indicator (EADI) and Electronic Horizontal Situation Indicator (EHSI). Three new sensors have been installed for aircraft position and attitude control: an inertial reference unit (IRU), an attitude and heading reference unit (AHRU), and a global positioning system (GPS). A flight management system with two Gemini 10 computers and a new radio management system have also been installed.
The Transalls provided NATO SIGINT in Bosnia .
For a number of years, France operated DC-8 aircraft "Sarigue" dedicated to ELINT. A reengined version, Sarigue-NG, went into service in 2000. The name stands for Systeme Aeroporte de Recueil d’Informations de Guerre Electronique (Airborne Electronic Warfare Information Gathering System) and also is the French word for Opossum, a shy and retiring animal. The updated aircraft was known as the SARIGUE-NG, with the NG standing for Nouvelle Generation or New Generation. Both DC-8s had a SIGINT system from Thompson-CSF, and operated in the Baltic, Mediterranean, French Africa, and during Desert Storm and NATO Kosovo operations.
It had a distinctive sideways looking airborne radar (SLAR) in a "canoe" under the fuselage, as well as large rectangular antenna arrays at each wingtip.
The aircraft was fitted with equipment developed by Thompson-CSF, similar to that installed in the earlirt Transall Gabriels. It is believed that the aircraft operated with a 24 man crew and as well as COMINT and SIGINT duties, it could even intercept mobile phone calls. Operated by the French Air Force on behalf of the armed forces and security services, it was seen in the Baltic, Mediterranean and French Africa, as well as being used in support of coalition operations during the Gulf War and NATO peace keeping operations in Kosovo.
On 19 Sep 2004, it was reported that in addition to a 50% cost overrun on an electronics upgrade by Thales, the weight of the new upgrade violated safety limits. The French Defence Minister confirmed the Sarigue would be retired because of ‘high operating costs’. An Airbus replacement for the DC-8 was considered and rejected.
Germany: Aircraft Platforms
Germany has selected a UAV platform for SIGINT, the EuroHawk version of the U.S. Air Force RQ-4 Block 20 Global Hawk. The aircraft is made by Northrop Grumman, with the airborne and ground station equipment from EADS. As with Global Hawk in the US, EuroHawk is approved to operate, unmanned, in the same airspace as commercial aviation. Five EuroHawks have been ordered so far, as a replacement for Germany's aging fleet of Breguet Atlantiques ..
Israel: Aircraft Platforms
Israel is reported to have converted at least four Boeing 707 aircraft, codenamed Re'em (Antelope) and based at Lod to an electronic warfare role, two for countermeasures and twp or more for SIGINT. An indicator of an ELINT role is the presence of a cheek-antenna array externally similar to the AEELS (Automatic ELINT Emitter Locating System) on the RC-135U/V/W. These aging aircraft are due for replacement, probably by Gulfstream G500 executive jets.
The aircraft are known as Re'em (Antelope) and are operated by 134 Tayeset at Lod. Some other IAF 707s are possibly configured for AAR/SIGINT operations. Israel is currently looking for up to 9 dual role aircraft to replace their 707’s and will purchase a number of Gulfstream G500s.
India: Aircraft Platforms
India appears to have a single 707 ELINT aircraft. 
Mexico: Aircraft Platforms
The Mexican Air Force has 2 Embraer P-99s and 1 Embraer R-99A. The R-99A is an Airborne Early Warning & Control aircraft AWACS equipped with the Erieye airborne radar from Ericsson AB of Sweden. The P-99 is the maritime patrol version of the R-99.It retains many of the C3I and ELINT capabilities of the R-99B.
Russia: Aircraft Platforms
Russian aircraft with SIGINT capability include the Tupolev Tu-142M-Z "Bear", the Beriev A-50 "Mainstay" (based on the Ilyushin 76 airframe) and the IL-38 "May" maritime patrol aircraft operate from bases in Syria, Al Anad Air Base and Khormaksar International Airport in South Yemen, and San Antonio de Los Banos and Jose Marti airbase in Cuba.
Saudi Arabia: Aircraft Platforms
Several 707 derivatives, originally used as KE-3 tankers, are being converted to two models of SIGINT suites by E Systems. Later versions are on the E-6 modification of the Boeing 707, the E-6 used by the US as a TACAMOcommand and control aircraft. 
According to the US Department of Defense, the Tactical Airborne Surveillance System and upgrades will be installed on Saudi E-3 and E-6 aircraft. The estimated cost is $350 million.
South Africa: Aircraft Platforms
Again with modified 707 aircraft, South Africa now operates 3 aircraft, apparently using the Israeli cheek antennas similar to the AEELS (Automatic ELINT Emitter Locating System) on the RC-135U/V/W.
These are expected to be replaced with Airbus 400 aircraft.
Spain: Aircraft Platforms
Spain operates a single 707 variant, modified by Israel and equipped with Israeli and Spanish electronics. As well as an Elta EL/L-8300 SIGINT system, In the baseline version, this multi-operator Elta system contains 0.5 to 18 GHz ELINT (0.03 to 40 GHz as an option), 20 to 1,000 MHz (2 to 1,500 MHz as an option) COMINT, and control and analysis sub-systems.
In addition to the SIGINT payload, the aircraft has a Tamam Stabilised Long Range Observation System (LOROS) high-resolution TV camera and recording systems. The SLOROS is reported to have a range of at least 62 miles (100km).
The aircraft has been reported around the western edge of North Africa, the Western Sahara and the Mediterranean.
Sweden: Aircraft Platforms
The Swedish Air Force operates the S-102B Korpen aircraft which is a modified Gulfstream G-IV business jet.
Turkey: Aircraft Platforms
Turkey has 6 C-130B ELINT aircraft.
United Kingdom: Aircraft Platforms
The British Nimrod R is a variant of a maritime patrol aircraft, but with exceptionally high speed, in-flight refueling capability, and long loiter time. Its sensors cover the tactical to strategic spectrum. It is reported to have a SIGINT suite from Thales.
UK E4D AWACS also have SIGINT capability.
United States: Aircraft Platforms
Some platforms considered strategic, including the P-3 and RC-135 RIVET JOINT aircraft, may be assigned in support of large tactical units. There are both MASINT and SIGINT versions of the RC-135, the best-known SIGINT variant being the RC-135V/W RIVET JOINT.
United States: Tactical Aircraft Platforms
In the 1950s and 1960s, SIGINT personnel flew aboard Navy EA-3B aircraft. As a result of ASA casualties during ground SIGINT in Vietnam, ASA developed its own fleet of tactical SIGINT aircraft, starting with the U-6 Beaver. The reconnaissance mission for these aircraft was indicated with an "R" prefix, hence RU-6. Beavers, however, had poor capabilities. The RU-1 Otter had more built-in SIGINT equipment, but the first purpose-built Army SIGINT aircraft was the RU-8D Seminole, which had a Doppler navigation system and wing-mounted direction-finding equipment, although SIGINT operations still required much manual work. Some RU-8D aircraft had MASINT sensors for categorizing specific transmissions. Especially with tactical aircraft, there was a gap between the knowledge of SIGINT personnel and the understanding of warfighters. For example, end users often expected a direction-finding fix to be a point, rather than an area of probability.
In 1968, the next tactical improvement was the RU-21 LAFFIN EAGLE and the JU-21 LEFT JAB, the latter being the first with computerized direction finding and data storage. Even more advanced ASA equipment was on P-2V aircraft borrowed from the Navy, and called CEFLIEN LION or CRAZY CAT platforms.
During the Vietnam era, six UH-1 helicopters were converted to SIGINT platforms, called EH-1 LEFT BANK aircraft and operated in direct support of combat aircraft.
US tactical SIGINT aircraft include the EH-60A Quickfix helicopter, which has interception capabilities in the 1.5-150 MHz and direction finding between 20-76 MHz. The EH-60L has better communications and ungradability than the A model, with the AN/MSR-3 TACJAM-A system . RC-12 GUARDRAIL aircraft provide a corps-level ESM capability, with the unusual approach of putting all the analysis equipment on the ground, with the RC-12K/N/P/Q aircraft acting purely as intercept and relay platforms. These aircraft normally fly in units of three, to get better cross-bearings in direction-finding.
The Navy EA-6B Prowler replaced the USAF EF-111 EW aircraft for all services, and the EA-6 is being replaced by the EF-18 Growler. All EW aircraft have some ELINT capability if for no other reason than targeting.
Naval MH-60R helicopters have AN/ALQ-210 ESM suites.
United States: Strategic Aircraft Platforms
The most common aircraft used in a strategic role by US allies are Boeing 707 conversions for the lower-budget, lower-capability installations, and Boeing 767 conversions for the higher-end. Gulfstream executive jets are another platform of interest. The US military is considering, as its aircraft age, replacing with variants on the foreign platforms, often built on US-made aircraft.
Some features are common to multiple countries, such as a pair are two "chipmunk cheek" bulges containing SIGINT antennas. There is a US made set used on the RC-135V and RC-135W Rivet Joint aircraft. A US-made variant, reported to have internal differences, is used by Saudi Arabia. A third variant, with a similar appearance, but of Israeli manufacture, are used by Israel and South Africa. In no case, however, are these the only SIGINT antennas on the aircraft. 
Dedicated C3I-ISR aircraft aircraft, operated by the US Air Force, are in a variety of SIGINT and MASINT configurations. An effort is underway to develop a standard RC-135 open architecture, allowing at least some of the aircraft to be quickly reconfigured. RC-135 RIVET JOINT is the most common SIGINT type, used for COMINT. These aircraft can be reconfigured to RC-135 COBRA BALL MASINT aircraft in increasing demand for monitoring ballistic missile launches. RC-135 COMBAT SENT aircraft are ELINT platform targeted against radars.
On the long-range Navy P-3 Orion maritime surveillance aircraft is the AN/ALR-66B(V)3 ELINT/MASINT system targeted against radars. Major improvements are an improved direction-finding antenna and an EP-2060 pulse analyzer.  The dedicated SIGINT EP-3 Aries II uses a JMOD (Joint Airborne SIGINT Modification) program to a JMOD common configuration (JCC).
Raytheon developed the SIGINT package for the MQ-4 Global Hawk UAV. Boeing has proposed a SIGINT variant of the P-8 Poseidon multimission maritime patrol aircraft it has under development. Raytheon and Northrop Grumman would be the partners for the actual SIGINT electronics. 
Boeing also has built a "Wedgetail 737" for Turkey, and appears to be marketing this as an alternative to the lower-end systems being built for business jets such as the Gulfstream. Australia also has ordered this aircraft.
- The Spyflight Website, 1 Jan 2007
- "737 AEW&C Wedgetail", Air Force Technology
- Puska, Susan M., ed. (August 2000), PEOPLE’S LIBERATION ARMY AFTER NEXTPeople's Liberation Army After Next, Strategic Studies Institute, U.S. Army War College
- Fisher, Richard Jr. (November 22nd, 2005), Growing Asymmetries in the China-Japan Naval Balance, International Strategy & Assessment Center
- "C-160 Transall Cargo Aircraft", Airforce-technology.com, Transall
- Wentz, Larry, Lessons From Bosnia: The IFOR Experience, IV. Intelligence Operations
- "Douglas DC-8 Sarigue NG", The Spyflight Website
- Northrop Grumman (February 1, 2007). Northrop Grumman, EADS Joint Venture Awarded $559 Million to Develop German Euro Hawk.
- DefenseLink (September 5, 1996), Memorandum for Correspondents
- The SAAF Forum (April 28, 2005), A400M deal signed
- "EL/L-8300 (Israel), AIRBORNE SIGNALS INTELLIGENCE (SIGINT), ELECTRONIC SUPPORT AND THREAT WARNING SYSTEMS", Jane's Radar and Electronic Warfare Systems, July 12, 2007
- Electro-optical payloads
- Pike, John. EH-60L Advanced Quick Fix.
- "Navy ISR", Sea Power, January 2006
- Boeing Integrated Defense Systems, P-8A Poseidon