An EC-130H deploys IR flares during a training mission over southern Arizona. Photo credit Gary Wetzel

Denying the enemy the ability to communicate is often equated with denying them the opportunity for victory. As the battle for Mosul continues in the drive to push the Islamic State from Iraq, the U.S Air Force is flying one of its most effective yet least known aircraft, the EC-130H Compass Call, on daily missions to deny ISIS military leaders and fighters the ability to communicate and coordinate defensive actions by shutting down their cell phones, radios, IEDs and very likely their new weapon of choice, drones.

Compass Call is not a household name like F-16 or F-15. Yet it’s one of the most important aircraft the U.S. Air Force has ever produced, and unlike so many defense projects that have struggled through their infancy, or even into adulthood, the 14 EC-130H airframes have been providing a robust airborne electronic attack since 1989 when they provided support to U.S Army Rangers during Operation Just Cause in Panama.


And this near-anonymity is what almost caused half of the airframes to be retired under a proposed Air Force budget request in 2015.

The mission of Compass Call is simple: locate the enemy, listen to the enemy, jam the enemy. To do this, Compass Call uses a unique set of capabilities that only it can bring to the battlefield, “throwing ‘trons” to attack enemy electronic systems and deny them the use of that equipment.


The effect of this disruption has been labeled “non-kinetic” as the denial is only temporary and not permanent in the way a 500 pound JDAM or HARM missile would be, but still provides the desired goal of negating combat effectiveness of the enemy.

A History Of Disruption

A weapon of the Cold War, Compass Call was originally designed to provide suppression of enemy air defenses (SEAD), and spent most of its early years running up and down the border between West and East Germany, taking hard looks at the integrated air defense systems, or IADS, that the Soviet Union and its Warsaw Pact allies had put in place.


In the event of war, Compass Call’s mission was to shut those systems down and to defeat the communications between enemy pilots and their ground controllers, exposing them to NATO’s fighter aircraft

Following Operation Desert Storm, where Compass Call disrupted Iraqi air defense systems during the air campaign and supported U.S. Army ground commanders during the re-taking of Kuwait, one very important lesson was learned: the need to marry capabilities with the signal intelligence capability of USAF RC-135s.

Almost a decade would pass before this became a reality when Project Suter was unveiled.


Project Suter provides a horizontal integration of multiple national and tactical platforms, such as the RC-135 and Compass Call. Sharing the signal intelligence information collected by the Rivet Joint community and their constellation of RC-135s with Compass Call allows for more effective employment of the aircraft’s jamming power, based solely on intercepts from Rivet Joint. Project Suter was fully funded shortly thereafter safeguarding the newly realized link between Rivet Joint and Compass Call.

Since September 11, 2001, the Compass Call fleet has witnessed an evolution of its capabilities and focus, utilizing both wide area and very precise, surgical jamming to support special operations forces or deny the enemy use of IEDs.

Over Iraq, Afghanistan and Syria the EC-130H fleet has also learned new tricks and exploited new technologies. Within the scope of one mission the crew could impact events both tactically and strategically, exploiting well refined system attributes to continue its dominance in information denial.


Currently engaged in the battle against ISIS in Iraq and Syria are four Compass Call aircraft deployed to the region to conduct electronic warfare operations. Four aircraft of an available 12; two are undergoing long-term modifications. That ratio should tell you how valuable these planes and their crews are.

Flying daily from Ahmed Al Jaber Air Base, Kuwait, the EC-130Hs find and attack the enemy forces with denial of service. To do this, linguists are heavily involved in the targeting process as Lt. Col Josh Koslov, the 43rd Expeditionary Electronic Attack Squadron commander told the Air Force News Service in December:

“(The linguists) weapon is language. They help us to efficiently find, prioritize and target (ISIL). They prioritize the signals we’re targeting from the strategic (level) through the tactical level and they also help the electronic warfare officer make jamming decisions in order to provide the effects desired by the ground force commander. We are inducing massive confusion and friction into their operations that make them ineffective as a fighting force.”


All 14 EC-130Hs, and the lone TC-130H trainer, are based at Davis-Monthan AFB, in Tucson, Arizona and belong to the 55th Electronic Combat Group (ECG). The airframes are divided between two operational squadrons, the 41st and 43rd Electronic Combat Squadrons (ECS), and the lone Compass Call formal training unit, the 42nd ECS, shares the available airplanes to train new crews.

As fast as commercial technology advances, the ability to counter these advancements must as fast or the battle will be lost before it begins. That is why Compass Call has been designed to be easily modified, using a spiral development process to ensure that the right equipment is in place.

Currently the EC-130H fleet is moving toward a common Baseline 2 configuration, with the first modified airframe delivered in February 2015. What that means is “fifth-generation electronic attack capability,” building on previous improvements such as the digital signal analysis and exciter subsystem (AXE), the IED Defeat subsystem (NOVA), and perhaps the single-greatest Compass Call add-on, the special purpose emitter array, or SPEAR pod, which arrived in 2006 with Block 35 of the Baseline 1 configuration.


The SPEAR pod, built by BAE Systems, took the capability of Compass Call from airspace superiority to cyberspace superiority. The SPEAR pods are 17 feet 2 inches in length and weigh 1,200 pounds and each EC-130H carries two of the extremely high power pods on the outer station on each wing.

Each SPEAR Pod is a phased array consisting of 144 discrete elements which are electronically combined to generate high power jamming, simultaneously producing multiple independently steerable beams from each pod to successfully oppose and jam even the newest and most sophisticated communication devices. With Baseline 2 the SPEAR pod has seen further enhancements to contribute to the overall mission of electronic denial.

Its Age Is Becoming A Problem

But as with everyone and everything, age takes its toll, and the EC-130H airframes have been feeling the pressure for years. In fact, the youngest EC-130H was purchased by the Air Force in fiscal year 1973 (the oldest was bought in 1964). Over 40 years old and with each aircraft averaging close to 1,200 flight hours a year, the need to deliver a replacement platform with the same capabilities is finally on the horizon.


The recapitalization of Compass Call has already begun and is expected to be officially awarded soon in what was a no-bid, sole-source contract, and with it the expectation of industry protests.

But then again, what would a major Air Force contract award be without a controversy or two, right?


Last week, the USAF confirmed what it had originally stated in 2016 about replacing Compass Call: the decision has been made to let aerospace and defense company L3 Technologies manage the program, including allowing L3 to choose the airframe that will replace the C-130 platform currently in use.

The deal is already done, according to Lt. Gen. Arnold Bunch, who is the Air Force Military Deputy, Office of the Assistant Secretary of the Air Force for Acquisition, who told Inside Defense:

“We are going with a lead system integrator. That lead system integrator is going to be L3, and they will make the selection of the aircraft, and they’re going to be the ones that lead the effort and they will incorporate and put mission systems into the platform. They have not made a selection of a platform… but we have made the decision on how we’re going to forward. We’ve already signed all the paperwork off. Now what we’re waiting to do is get the bill and then we’ll go forward.”


The bill Lt. Gen. Bunch is referring to is the defense spending bill for 2017, which Congress has yet to pass, choosing instead to extend current funding levels through April, when it is expected the Trump administration will deliver its version of the 2017 defense budget to Congress.

L3 is the natural choice to handle the system design and incorporation into the new airframe, which has acquired the designation EC-37B. BAE Systems is expected to build the electronic warfare systems on the new aircraft as well.

It appears all but certain the replacement airframe will not be based on the C-130, such as the capable and plentiful C-130J, which is still in production by Lockheed Martin, but rather incorporating the Gulfstream G550 business jet to carry the necessary equipment to continue the electronic attack mission.


The Israeli CAWC based on the Gulfstream 550, similar to what the EC-37B may look like. Photo credit Gulfsteam

The Gulfstream 550 is no stranger to conversion for military use. The USAF currently flies three as the C-37B, conducting special airlift missions around the world for defense and government officials, and the U.S. Navy has an equal number for the same task.

The Navy has also ordered a highly-modified Gulfstream 550 to do range work over the Pacific coast, replacing two aging aircraft based on the P-3 airframe. This Gulfstream will be very similar in appearance to the Israeli conformal airborne early warning aircraft (CAWEW). Israel converted five airframes to this specification for use, and has exported versions to Italy and Singapore.


Boeing had offered a version of its 737 as the Compass Call replacement and Canada’s Bombardier put forth its G6000. Bombardier did file a protest at the decision for no-bid, sole-source contract but for now their protest has been shelved, at least until the USAF makes it official that L3 will handle the contract. Then Bombardier is free again to protest the process. Boeing has yet to offer any protest on the pending announcement, but may very well do so once it is made official.

No decision on the crew size of the EC-37B has been made, though it is certain to be smaller than the current Compass Call crew of 13 by virtue of eliminating the flight engineer and navigator. The automated G550 will most certainly perform these functions.

What’s Next?

Currently 10 EC-37Bs are planned to replace the 14 aging EC-130s in a process which will see both airframes operating concurrently for quite some time.


Congress has mandated that the Air Force initially purchase only two aircraft in order to validate the platform’s ability to fulfill its tasking before allowing the remaining eight to be purchased. Defense News reported earlier this year that the USAF had put $63 million into a “wish list” for additional funding during 2017 to help move along the Compass Call replacement.

Compass Call is a true national asset, and the need for a replacement aircraft has lingered on for way too long. Faced with the choices of replacing entire classifications of fighters and attack aircraft, tankers and bombers almost simultaneously has stretched the available budget and kicked the can down the road for years.


With tired airframes that have been used twice as much as originally planned and for a different purpose than originally built, Compass Call has been nothing if not resilient. However, the hope for smooth transition to the EC-37B is almost an illusion.

Very, very few defense projects move quickly anymore, and with the prospect of at least one company prepared to contest the decision to allow L3 to run the program, delays are inevitable, regardless of how big and bright red the letters URGENT are stamped on the program.

Gary Wetzel is an experienced military and aviation writer who has authored two books examining the combat operations of the A-10 Warthog in Afghanistan. He also served over six years in the U.S Navy as sonar technician aboard USS Philadelphia and USS Dallas.