September 19, 2022: In 2017 the U.S. Air Force decided to replace its elderly EC-130H Compass Call electronic warfare aircraft with the EC-37B, a smaller aircraft based on the G550 business jet. By mid-2022 the first production model of the EC-37B was being flown to bases where personnel using the older EC-130H could see up close the replacement aircraft. In a few years the EC-37B will replace the remaining EC-130H aircraft. The air force also developed a software-based EMS (electromagnetic spectrum) warfare system to replace the less-flexible hardware-based system used by Compass Call aircraft. This new SABER (Small Adaptive Bank of Electronic Resources) is easier to update with new capabilities. The first five EC-37Bs will have the existing electronics installed while subsequent aircraft will have SABER. Eventually all EC-37Bs will be equipped with SABER.

The EC-130Hs are worn out from extensive use in Iraq and Afghanistan. That’s because the air force discovered that for eavesdropping and jamming, a single EC-130H Compass Call electronic warfare aircraft could dramatically cripple Islamic terrorist communications. The problem was the air force only had only 14 EC-130H aircraft in service and they were (and still are) in heavy demand.

EC-130H were introduced in the early 1980s and designed to jam Soviet anti-aircraft defenses. The Cold War ended before the EC-130H had a chance to do what they were designed for but later proved invaluable in Afghanistan and Iraq. Since 2002 these 14 aircraft have flown nearly 7,000 sorties and spent over 40,000 hours in the air.

What made the EC-130H so useful was its ability to eavesdrop on cell phone and other radio communications and then selectively jam them. The EC-130H has space on board for linguists, who can listen to the radio traffic below, and decide who to just record (and perhaps immediately report to U.S. troops below), and who to jam. This information can also be shared in real-time with people on the ground. Because Afghanistan has limited land-line phone systems, especially in the countryside, the Taliban, and everyone else, relies on cell phones, walkie-talkies and ham radio type gear to communicate. The EC-130H can detect all of these, and jam or eavesdrop on them selectively. ISIL has similar preferences in communications gear and in the midst of combat they have found, like the Taliban, there is no solution to the problems created by an EC-130H overhead.

Another advantage is that while most Islamic terror organizations know of these aircraft, they never know when there are operating nearby unless there is obviously selective jamming going on. This forces the enemy to either use their cell phones and radios sparingly, or use code words (which the U.S. can usually decipher, or just jam) or not use electronic communication at all. The latter choice makes it more difficult to control your forces in a rapidly changing battle.

The U.S. began using EC-130Hs frequently over Afghanistan in 2006. There they flew 300-400 sorties a year, each 6-8 hours long and they were considered a valuable tool by ground commanders. But only the most crucial ground operations got EC-130H support. The use of these aircraft increased greatly, but gradually, as tactics and techniques for their most efficient use were developed. The U.S. Army also has some two engine electronic eavesdropping aircraft but these are not as well-equipped as the air force EC-130Hs. Nevertheless, the army sent as many or these twin-engine aircraft as possible to Afghanistan and Iraq and constantly sought to buy more.

The need for something like the EC-37B became acute as the air force proposed to retire half the EC-130H fleet in order to provide more money for F-35s and the new heavy bomber. The elderly 69-ton EC-130H aircraft are expensive to operate and mainly support ground combat operations, while air force leaders prefer jet fighters and heavy bombers.

The air force agreed to another solution and move electronic warfare equipment currently on EC-130Hs to a long-range business jet, something which has become increasingly common worldwide. The 40-ton Gulfstream G550 is being used rather than the four-engine turbo prop C-130. This is part of a trend which proved the twin-engine business jets are cheaper to buy and operate while getting the job done as well as older aircraft based on larger transport aircraft. This use of business jets became particularly attractive once the G550 was introduced in 2004.

The G550 became particularly popular for this sort of thing after Israel showed it could be successfully used as an AWACS (Airborne Warning and Control System) aircraft. This occurred in 2008 when Israel introduced a new AWACS design based on the G550 fitted out with Israeli made radar and electronics. The Israeli Air Force ordered these CAEW (Conformal Airborne Early Warning) AWACs in 2006 and the first two entered service in 2008. Israel had already sold the AWACS electronics to India, for installation in four Russian Il-50/76 aircraft but realized the CAEW gear could work on a smaller aircraft. Singapore, Italy, Australia and the U.S. Navy later bought CAEWs fitted to G550s.

The CAEW AWACS carries a Phalcon conformal (it is built into the lower fuselage) phased array radar, SIGINT equipment (to capture and analyze enemy electronic transmissions), and a communications system that can handle satellite signals as well as a wide array of other transmissions. There are six personnel on board to handle all this gear, plus the flight crew. The Gulfstream G550 used for this can stay in the air for over ten hours per sortie and can fly at up to 13,200 meters (41,000 feet).

The G550 based EC-37B uses the same CAEW technology now used in EC-130Hs into the G55o. The air force will do one of these conversions a year until at least half the Compass Call aircraft are G550s rather than C-130s. Other nations have used the same basic idea of attaching the various sensors an airborne electronic intelligence aircraft needs to the fuselage of the G550 and then put most of the electronics, plus the equipment operators, inside the aircraft. By the time the G550 appeared electronics, both sensors, computers and displays, had gotten lighter, cheaper, more reliable and more powerful. A smaller aircraft was the way to go.

The G550 is a larger version of the Gulfstream G400, which the U.S. Army uses as the C-20H transport. The U.S. Coast Guard, Air Force, and Navy also use militarized Gulfstreams (usually as C-37Vs). The 30 meter (96 foot) long aircraft has two engines and was built for long flights (over 11,000 kilometers). Current Gulfstream G550s cost about $40 million each.