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Analysis: Compass Call Sundown

The end of the EC-130H is nigh, we examine the subsystems and capabilities which will equip its replacement

On 9 July BAE Systems announced it had commenced work on the ‘Cross Deck Initiative’ to transfer subsystems from the US Air Force’s Lockheed Martin EC-130H Compass Call Electronic Warfare (EW) aircraft onto new Gulfstream EC-37B platforms: an initiative which the firm is jointly pursuing with L3 Technologies.

According to an official announcement on BAE Systems’ website the company “will re-host the EC-130H’s mission equipment onto a higher-performing aircraft.” The performance improvements of the EC-37B vis-à-vis the EC-130H, BAE Systems continued, will be seen in the higher altitudes, longer ranges and higher cruising speeds. As a means of comparison open sources note that the EC-130H has a flight ceiling of 25,000 feet/ft (7,600 metres/m) compared to the 51,000ft (15,545m) of the Gulfstream G-550 business jet upon which the EC-37B is based. Similarly, the EC-130H has a range of 2,295 nautical miles/nm (3,694 kilometres/km) as opposed to the 6,750nm (12,501km) of the G-550 while the cruising speed of the EC-130H is 258 knots (478 kilometres-per-hour) as opposed to the 459 knots (850 km/h) of the G-550. BAE Systems’ information continued that the EC-37B airframe will be based upon the G-550 Conformal Airborne Early Warning Aircraft (CAEW). This design has been developed by Gulfstream’s Special Missions Aircraft department. This aircraft, which has been outfitted with Israel Aerospace Industries’ EL/W-2085 L-band (1.215 gigahertz/GHz to 1.4GHz) and S-band (2.3GHz to 2.5GHz/2.7GHz to 3.7GHz) airborne early warning radar equips the Israeli Air Force, and its Italian and Singaporean counterparts. In the Signals Intelligence (SIGINT) domain, the Royal Australian Air Force is acquiring a pair of G-550s configured for this mission with L3 Technologies leading the effort. It is entirely possible that these planes will carry a variant of the USAF’s Boeing RC-135V/W Rivet Joint SIGINT mission fit. For more details on the specification of the RC-135V/W please see the author’s ‘Good Listeners’ article in Issue-7/8 of Military Technology magazine. The G-550 airframe can be adapted to host subsystems which require dedicated antennae and to support such missions the aircraft has been outfitted with large fuselage, and fore and aft fairings to accommodate these.

The mission performed by the EC-130H make it imperative that the EC-37B has sufficient exterior space to house the aircraft’s external antennae, alongside available interior volume to comfortably accommodate the mission specialists tasked with performing the aircraft’s mission. According to the USAF, the EC-130H “disrupts enemy command and control communications and limits adversary coordination essential for enemy force management.” The aircraft’s mission follows the communications jamming dictum ‘if you can’t talk, you can’t fight.’ The EC-130H’s mission was originally envisaged to jam the vital radio communications upon which the smooth functioning of an integrated air defence system depends, but has since evolved to include the jamming of hostile tactical communications on the battlefield, ground-based air surveillance radars, insurgent communications and even Improvised Explosive Devices (IADS).


The aircraft’s array of subsystems explains how performs this diverse array of roles. The EC-130H fleet, is spread across the 41st and 43rd Electronic Combat Squadrons (both part of the 55th Electronic Combat Group located at Davis-Montham airbase, Arizona). Public sources state that the USAF has a total of 14 EC-130H aircraft incorporating EC-130H Block-30/35 Baseline-1/2 platforms. According to official US government documents this fleet breaks down into ten aircraft which are in the primary mission inventory, four of which are in the back-up aircraft inventory and a single platform which is used as a testbed. The USAF does not provide a breakdown as to precisely how many of these aircraft are of which configuration, but its literature stipulates that the EC-130H Block-35 Baseline-1 possesses “additional capabilities to jam communication, (ground-based air surveillance radars) and navigation systems through higher effective radiated power, extended frequency range and insertion of digital signal processing versus earlier EC-130Hs. Baseline 1 aircraft have the flexibility to keep pace with adversary use of emerging technology.” US Congressional Research Service documents published in 2016 state that the USAF is transitioning all of its aircraft to the EC-130H Block-35 Baseline-2 configuration (see below).

Over the years, the EC-130H has received a number of important enhancements. The EC-130H Baseline-1 configuration outfitted the with a number of specific subsystems to support its Electronic Attack (EA) mission. These included Raytheon’s AN/ALQ-175 high-band RF jammer, AN/ALQ-198 low-band RF jammer and AN/ALQ-173 ‘blink’ jammer: The latter is thought to be used to provide an EA capability against monopulse radars causing the radar’s line-of-sight to continually move between two positions preventing an accurate fix on a target. The aircraft’s EA capabilities are enhanced with the Generic Comms Jammer, which does not appear to have been given a specific US Department of Defence nomenclature. This is used for the communications jamming portion of the aircraft’s mission. For the gathering of electronic intelligence, this EC-130H configuration carries an Argo Systems AN/ALR-63 instantaneous frequency measurement receiver which is thought to have a detection range in the region of 500 nautical miles (926 kilometres) and provides up to three degrees of direction-finding accuracy.

Later Capabilities

Details of the EC-130H Baseline-2 specification are more sketchy, although official US DOD documents articulate that such equipment includes the Digital Signal Analyser and Exciter (AXE), BAE Systems’ Special Purpose Emitter Array (SPEAR) which can jam multiple emitters simultaneously via the transmission of four steerable, independent jamming beams. The SPEAR pod is a particularly interesting capability. Open sources note that the pod can cover Very High Frequency (VHF) and Ultra High Frequency (UHF) wavebands of 30 megahertz to three gigaherz. Also hosted on the aircraft is the Integrated Modern Communication Receiver and Phased Array Transmit/Receiver antennae and Tactical Radio Acquisition and Countermeasure Subsystem (TRACS-C). This is thought to have replaced the aircraft’s legacy AN/ALR-63 subsystem. US-led combat operations in Afghanistan from 2001, and in Iraq from 2003, underscored the effectiveness of the SPEAR pod when used in conjunction with BAE Systems’ AN/USQ-113(V)3 communications jamming system equipping the US Navy (now retired) and US Marine Corps’ EA-6B Prowler electronic warfare aircraft. Evidence suggests that in both theatres the EC-130Hs would perform precision spot jamming against specific communications threats, while the EA-6B would perform barrage jamming across other adversary communications networks.

The EC-130H’s subsystems configure the aircraft to not only perform Electronic Attack (EA) against an adversary’s military communications, but also against civilian communications. Recent operations have shown this latter capability to be particularly important. For example the Islamic State of Iraq and Syria (ISIS) has made widespread use of civilian cellular and radio communications for command and control during their operations in both countries. US-led combat operations against ISIS under the Operation Inherent Resolve banner have witnessed significant activity by USAF EC-130Hs to disrupt these communications, and since 2016 open source reports have noted that these aircraft have been particularly active in the Iraqi and Syrian theatres. The aircraft was also deployed to support US and NATO-led operations in Libya in 2011 as part of Operations Odyssey Dawn/Unified Protector to uphold sanctions and arms embargoes against the Libyan government, and to protect Libyan civilians against forces loyal to the country’s erstwhile dictator Colonel Muammar Gaddafi. During this conflict, the aircraft played an important role in jamming both Libyan armed forces military communications, and also public sector and civilian radio communications which it was feared were being used for military command and control, according to the author’s sources. Furthermore, the aircraft is furnished with the Improvised Explosive Device (IED) defeat subsystem called NOVA, which plays an important part in helping to neutralise IEDs and is a useful by-product of the aircraft’s jamming mission. Radio-controlled detonation either using cell phones or RF (Radio Frequency) remote control has long been a favoured method by insurgents to detonate an IED. The EC-130H’s EA capability allows the aircraft to also jam such devices, or alternatively to transmit RF to pre-detonate them before they become a threat to friendly forces.

While neither BAE Systems nor the USAF chose to divulge more details on the EC-130H equipment that will be ‘cross decked’ onto the new EC-37B it is widely thought that this process will comprise several, if not all, of the aircraft’s subsystems including the SPEAR pod, NOVA and TRACS-C subsystems. Moreover, sources have informed MONch that all ten EC-130H subsystem ship sets will migrate from the former to an identical number of EC-37Bs in the coming years.

Thomas Withington


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