EA-18G Growler: 21st Century Electronic Attack

AIR International details the Boeing EA-18G Growler electronic attack aircraft and its Next-Gen Jammer, as Mark Ayton considers what lies ahead for this sophisticated node in the modern battlespace.

Boeing’s EA-18G Growler dates back to a 2001 requirement from the US Department of the Navy for an analysis of alternatives for a new electronic attack aircraft to replace the EA-6B Prowler. The EA-18G, an advanced derivative of the F/A-18F Super Hornet, was selected as the ideal as a stand-off and escort jammer for the US Navy. Now in its second decade of US Navy service, the EA-18G continues to be the only dedicated tactical electronic attack aircraft in the US Department of Defense (DoD) inventory.

CAPT Jason Denney, the US Navy F/A-18 Hornet and EA-18G Growler programme manager with Naval Air Systems Command’s PMA-265, said the aircraft has a fantastic ability to disrupt signals, deny communications, jam radars and provide crucial support and intelligence: “The Growler’s ability to work with all other aircraft, not just those in the carrier air wing but within the DoD, makes it a critical node operating with deployed air force, army and marine corps expeditionary units – interoperability is a large key performance parameter for the Growler.”

Naval Air Systems Command (NAVAIR) dedicated three Super Hornets to Growler flight test in July 2004. All three were fitted with wingtip pods and other sub-systems with the same weight, centre of gravity and aerodynamic characteristics representative of the latest equipment for the new variant.

The first aircraft to fly configured as an EA-18G was F/A-18F BuNo 165875 (F35), which started testing on March 30, 2006. Air Test and Evaluation Squadron 23 (VX-23) ‘Salty Dogs’, based at NAS Patuxent River, Maryland, undertook 346 flights with this jet. Mission systems testing of the first System Design and Development (SDD) EA-18G (EA-1) started in the anechoic chamber at ‘Pax’ in late October 2006.

Growler Mission Systems at a Glance

• ALQ-99 tactical jamming pods with separate low-band and high-band configurations.

• ALQ-218 digital receiver system (wingtip pods).

• ALQ-227 communications countermeasures system and electronic attack unit.

• AN/APG-79 active electronically scanned array radar.

• INCANS (interference cancellation system) to enable UHF communications to be made during jamming.

• Multi-mission Advanced Tactical Terminal (MATT) satellite communications receiver.

Growler Wizardry

The EA-18G’s primary antenna is the ALQ-218, housed in its wingtip pods, with additional antennae located in the forward and aft sections of the airframe, appropriately separated so the system correctly processes signals. Threats can be detected throughout the radio frequency (RF) spectrum, measured in small elements. The signal is handed over to a secondary receiver, which measures very fine and parametric measurements of the frequency and amplitude. Geo-location of the threat is calculated by interferometry – measuring differences in phase, and the waveform angle relative to the aircraft's position.

Growler system software is aligned with that of the Super Hornet, but with specific electronic attack elements in a ‘third level’. Recognition of the aircraft’s electronic attack systems and the ALQ-218 activates this ‘third level’ and the pilot and weapons systems officer (WSO) use HOTAS (hands-on throttle-and-stick) controls to view, operate from and switch between modes.

Paring down the EA-6B’s four-person crew to just two in the EA-18G required a lot of automation. The WSO’s advanced crew station (ACS) interlinks seamlessly with the pilot and permits the two-person crew to operate the systems with full co-ordination.

Ops Around the ‘Boat’

Development from the Super Hornet ensured that the EA-18G was readily suited to carrier operations – its core role. Bring-back is a term related to the stores load that an aircraft is able to carry and still safely recover to the carrier’s flight deck. The Growler’s only releasable stores are its weapons or drop tanks – the former being its kinetic weapons: the AGM-88 High-Speed Anti-Radiation Missile (HARM), AGM-88E Advanced Anti-Radiation Guided Missile (AARGM) and AIM-120 Advanced Medium-Range Air-to-Air Missile (AMRAAM). During carrier suitability trials, VX-23 undertook gross-weight expansion testing to increase the Growler’s bring-back capability to 48,000lb (21,773kg) including fuel, up from the Super Hornet’s 44,000lb (19,958kg) load. Catapult shots had to ensure tow-bar, nose-bar, gear and hook point loads were within the required limits for launching the aircraft. Arrested landings with a gross weight of 48,000lb (21,773kg) were conducted under various simulated conditions to test de-acceleration, high-sink rate landings, roll/yaw offset landings and different attitudes.

Tactical Jamming

As well as its built-in systems, the Growler team took a risk-reduction approach when it came to the electronic attack mission. The EA-18G carried over the Prowler-era ALQ-99 tactical jamming pods. Continual upgrades enabled these to remain relevant against potential threats, but were taken on as an interim capability for the Growler.

Two different variants of ALQ-99 pod are dedicated to notional wave bands and therefore target sets and attack solutions. Over the past 35 years, ALQ-99 pods have been upgraded by either waveband, RF exciter or universal exciter. Back in 2005, these pods hit their technology ceiling. Certain new target sets – those of a communication or asymmetric warfare type – can be accommodated with small tweaks, but for the latest surface-to-air missile (SAM) systems, the ALQ-99 was at the end of the line.

The search for a replacement Next Generation Jammer (NGJ) was completed in April 2010. In November of that year, a resources, requirements and review (R3) board sat at the Pentagon and provided validation to build a new system for the EA-18G. During 2010, technology and maturity contracts were awarded to Raytheon, Northrop Grumman, ITT/Boeing and BAE Systems to look at maturing the requisite technology for NGJ.

Providing sufficient power and cooling for an electronic attack capability on a tactical aircraft is a major challenge. Power generation needs to be built into the pod. The ALQ-99 uses a small RAM air turbine, a small propeller on the front end. This solution wasn’t an option for the NGJ because of constraints caused by solid state and active array technologies – with the new solution being an internal RAM air turbine generator – dubbed RAT G.

The new advanced arrays also present unique challenges. An AESA radar works best using a large flat plate, an arrangement that allows a beam to be formed by focusing a lot of energy. Electronic attack is no different – requiring efficient beam formers and amplifiers. Use of gallium arsenide circuits for close to 100% duty cycle jamming required mature technologies. Development contracts were awarded to specialist companies in 2010, with follow-on technology development contracts in 2012.

Next Generation Jammer

Under the Joint Electronics Type Designation System, the NGJ Mid-band is dubbed the ALQ-249; a high-powered, agile, electronic attack system capable of operating at stand-off ranges, attacking multiple targets simultaneously with advanced jamming techniques designed for rapid upgrades with a modular, open systems architecture. Equipped with agile AESA and an all-digital back-end, the ALQ-249 conducts precise jamming assignments against advanced and emerging threats operating throughout a wide range of radio frequency bands.

Confronted with integrated air defence system radars, communications and data links, the ALQ-249’s ability to engage threat systems and conduct robust jamming at standoff distances is vital. Consequently, the ALQ-249 must provide sufficient effective isotropic radiated power (EIRP); the measured radiated (output) power of an antenna in a specific direction.

In addition to the technical complexity and the necessary size and all-up weight restrictions of a new-generation electronic attack pod, the NGJ design team was faced with other constraints. The EA-18G Growler embarked as part of a carrier air wing endures the rigours of flight deck catapult launches and arrested landings. Its operation involves emission of electromagnetic and directed energy to degrade, neutralise or destroy an enemy’s combat capability, which requires careful control and management to ensure both the aircrew and the aircraft are not adversely affected.

So what are the defining design drivers for the NGJ pod? According to CAPT Michael Orr, programme manager for electronic attack systems, there are four. Power requirement, driven by operational scenarios; power generation capability, which defines the cooling requirement; processing power, which must enable all of the pod’s combat functions, many of which are automated; airworthiness, which includes integration constraints, structural limits and system software integration.

In performance terms, each of the four elements had to be balanced and optimised against each other to produce the required capability.

Once integrated with the EA-18G, the ALQ-249 will be capable of contributing to the full range of warfare, from air strikes in anti-access/area denial environments to the type of irregular warfare encountered in Afghanistan.

One outcome of the November 2010 R3 board was to return the NGJ programme into incremental capabilities. Increment 1 is the mid-band, which covers the most critical threat waveforms across a full spectrum of agile and adaptive communications, data links and non-traditional radio frequency targets. Increment 1 will be used to deny, degrade or deceive use of the electromagnetic spectrum employing both reactive and pre-emptive jamming techniques and is currently in the engineering and manufacturing development (EMD) phase.

Increment 2 is the low-band, which includes important threat waveforms and has an initial operating capability (IOC) targeted for after 2022. Increment 3 is the high-band with an IOC after 2024. This will be housed in a smaller pod carried on the outer wing stations 2 and 10. NAVAIR currently describes Increment 2 and Increment 3 as planned future efforts.

April 2016 was an important month for the NGJ Mid-Band programme as it received Milestone B approval to enter EMD and Raytheon was awarded a 56-month contract valued at US$1 billion for execution of the phase. In accordance with the contract, Raytheon will deliver 15 EMD pods to be used for mission systems testing and qualification, and 14 aeromechanical pods for airworthiness certification.

On April 27, 2017 the NGJ programme completed its critical design review (CDR) – it identified deficiencies that deemed a redesign of the pod structure, which caused schedule and cost breaches. Despite the structure redesign, manufacturing, integration and testing of the antenna arrays, power generation system, software and common electronics unit continued in accordance with the EA-18G H16 software integration schedule.

On October 18, 2017 a memorandum of understanding was signed with Australia – the only other current operator of the EA-18G – forming a joint programme office and a co-operative development project.

NGJ in Testing

NAVAIR’s anechoic chamber at Patuxent River is currently occupied by an EA-18G fitted with the first set of two EMD pods. The aircraft and pods were first placed in the chamber last November, and to date have undertaken more than 400 hours of testing with both pods radiating to check basic functionality and to capture electromagnetic interference data. The latter being the measurement of radiation data which is used to ensure the pod does not overheat or adversely affect the aircraft and the aircrew. Data captured in the chamber is also being used to gain an interim flight clearance authorisation to operate a Growler fitted with a set of NGJ pods in non-standard configurations, in different flight envelopes and conditions. The chamber testing is now providing real data, as opposed to analysed data, for use in the mission system modelling process to begin validation. Prior to that, extensive mission system modelling of the pod’s application to electronic attack and jamming was based entirely on analysed data captured from ALQ-99 pods in operational scenarios.

Last summer, Raytheon delivered the first NGJ Mid-Band EMD pod to Patuxent River to begin initial stores integration. This includes verification of ground procedures, mass properties, aircraft installation and built-in test checks, all in preparation for chamber and flight-testing.

Different types of tests require different configurations of pods, such as fatigue, static, jettison and aeromechanical versions – the latter used for flying qualities and aircraft integration. Pods used for mission system testing are in full-up configuration with all of the sub-systems installed. Unsurprisingly, mission system pods are expensive and are actually unnecessary for some elements of the flight test programme.

Prior to first flight, the NGJ pod is undergoing all of the standard tests required for stores integration. Fit and function checks were completed in the early autumn of 2019, followed by drop testing. Once flights begin, a set of NGJ pods will undergo captive carriage tests; loads, environmental, flying qualities, performance, drag and structural integrity. Performance and jettison tests will follow as part of the employment phase.

CAPT Orr described the forthcoming NGJ flight-test programme as “thorough and extensive”, involving hundreds of missions. It will involve aero mechanical testing of the pod’s physical integration on the aircraft; mission systems testing of the pod’s performance and, ultimately, carrier-suitability testing.

The ‘Salty Dogs’ of VX-23 will conduct the NGJ flight test programme. The squadron hosts five Growler aircraft and will receive a series of pods during March and April 2020 for its work; the set of pods currently in the chamber will not be used for flight test. Flight-testing was expected to start this spring and to continue through most of 2021.

Chamber testing will continue for quite some time as its focus changes to increased performance. Milestone C, the low-rate initial production decision, was anticipated at the end of Fiscal Year (FY) 2020.

An operational test readiness review should take place by early 2022. If the review is successful, the NGJ pod will enter operational test that year, followed by an IOC declaration in FY 2022.

NGJ in Testing

In 2019, Raytheon contracted Calspan to fly a Gulfstream III test bed aircraft fitted with a trials pod designed specifically for power generation testing and risk reduction efforts in support of the NGJ’s initial flight clearance process.

Raytheon’s NGJ test pod was configured with a RAT G to demonstrate the functionality, mechanical interfaces and controls of the RAM air turbine.

The turbine’s design requirements are significant to such an extent that the Gulfstream test flights were planned from the start of the programme, and named the prime power generation capability, or PPGC.

Orr said the testing was conducted as a risk reduction effort because the RAT G was identified as a potentially troublesome area early on in the NGJ programme. NAVAIR set the test objectives and observed the flights carried out by Raytheon and Calspan. Orr said: “There really were no surprises during the test flights. The objective was to validate some of the assumptions we held, but the data captured did not lead to any design changes.”

Operational Flight Programmes

The NGJ pod runs on its own operational flight programme (OFP) software, which is independent, but aligned with the Growler’s own OFP. The Growler runs on high order language OFPs – designated by the letter H. The NGJ will be integrated and enter fleet service with EA-18G Growler aircraft using H16 software. So critical is alignment of the two OFPs that the PMA-234 NGJ programme office has an NGJ integration team that works on a daily basis with the PMA-265 Growler programme office team. CAPT Orr said PMA-234 staff understand the H16 software schedule and the releases and tie the NGJ pod releases, from a capability perspective, to the corresponding H16 releases, to ensure that when that is delivered to the fleet it will be able to use NGJ.

Explaining the process, Orr said: “We use the interface control documents issued to us by PMA-265, for hardware and software, and fully understand what the constraints are with H16. If we need to update the pod’s software, to the maximum extent possible we design it such that we can update the pod without having to touch the H16 OFP. If a situation arose in which we wanted to add capability to the pod that would not run on the existing aircraft OFP, we would likely delay until the next aircraft OFP was released.”

Given that electronic warfare is constantly evolving, an electronic attack pod needs to keep pace with emerging threats. This requires labs to be able to quickly tweak the pod without the need to change the OFP. According to Orr, the pod’s capability can be updated for the majority of conditions independent of the OFP.

Growler’s Continuous Improvement

As part of the Growler road map, the aircraft is continually improved primarily through a roughly biennial OFP software drop. The H12 release included enhanced ALQ-218 geolocation, communication countermeasures set improvements, display improvements to enhance air-to-surface, air-to-air and counter electronic attack sensor integration to manage aircrew workload, and additional capabilities to operate in ATC-controlled airspace. H14 began operational testing in October 2018, and concluded earlier this year, and has just been released to the fleet. In July, live-fire missile testing was undertaken to demonstrate the integration of the AIM-120 with the Super Hornet and Growler aircraft operating with the H14 software.

PMA-265 is now under way with the developmental test of the subsequent H16, which includes: software and hardware upgrades to the ALQ-218 digital receiver – an open architecture, multi-level secure processor known as the Distributed Tactical Processor-Network (DTP-N) which is reckoned to be 17 times more powerful than the original Growler system; and the Tactical Targeting Networking Technology (TTNT) – a high throughput, low latency data link with satellite communications for advanced network connectivity.

Equipped with DTP-N and TTNT, a pair of Growlers will be able to fuse data acquired by on board and off board sensors to generate a common tactical picture of the battlespace and rapidly exchange that information with other assets. What does that achieve? It enhances targeting capabilities and improves air-to-air timelines and performance. This capability is scheduled to be implemented with several H-series software builds.

Back in August 2017, the US Navy staged a series of fleet experiments called ‘Netted Sensors 2017’, conducted by the Navy Warfare Development Command involving, among others, F/A-18 Super Hornet and EA-18G Growler aircraft.

The focus of the experiments was sensor networking over the TTNT data link to enable distribution of information from around the maritime battlespace to all participating assets; aircraft, ships and shore stations.

EA-18Gs were focused on working a common tactical picture, multi-ship electronic surveillance, Growler manned-unmanned teaming and network-centric collaborative targeting (NCCT) technologies. It meant they were using joint data standards and interfaces to speed up sensor cueing and targeting through to launching strikes in multi-sensor geolocation events.

CAPT Denney outlined other initiatives to deliver new capability to the fleet faster to outpace potential threats, to improve and sustain aircraft mission capability rates by using predictive maintenance in order to spend time performing effective and proactive maintenance rather than reactive maintenance.

One change already in effect and in support of the above is migration from multi-sensor integration to multi-system integration. This allows for insertion of new technologies and requirements to keep pace with the fleet’s demands; this will continue with H16.

Block II Growler and the Number One Mission

Ongoing work is defining a Block II capability development programme for the EA-18G, which will include conformal fuel tanks in pretty much the same configuration as those under development for the Block III Super Hornet. Similarly, the ACS featuring a large area display and low-profile head-up display will initially deploy on the Block III Super Hornet and then the Block II Growler.

Growlers are not equipped with a cannon, but the internal space is not left empty, it’s fitted out with an airborne electronic attack palette, which will be replaced in Block II to overcome obsolescence.

Given the relatively small fleet of aircraft, their ongoing utilisation rates and an out-of-service date currently pitched for the mid-2040s, PMA-265 is already conducting a service life assessment programme (SLEP) to assess utilisation and when a SLEP will need to start. Denney explained that because of the Growler’s utilisation, a SLEP would not begin until after conversion to the Block II is complete: “We are forecasting 2025 as the Block II IOC,” he explained.

When asked whether the PMA-265 team will be able to stay ahead of fast developing emerging threats, Denney said it was the team’s number one mission: "Our motto is to support, to sustain and advance the fleet. That is what we do, whether that’s getting the mission capability rate above 80% or making sure the aircraft is able to fight and win against potential adversaries, that is why we make incremental improvements. We are developing the Block II Growler to exceed the capabilities of our potential adversaries.”

Growler goes Unmanned

Last October, the latest iteration of the US Navy's Fleet Experimentation (FLEX) programme was staged. According to Navy Warfare Development Command, FLEX examines various solutions to cover capability gaps. Additionally, it embraces innovative concepts, tactics, techniques, and procedures, as well as concepts of operation.

Last October's FLEX included three EA-18G Growlers assigned to VX-23 that were fitted with a control system called Artificial Reasoning and Cognition (ARC) and prototypes of the DTP-N and TTNT. The name of the control system implies it's an artificial intelligence (AI) machine (computer) that mimics the reasoning and cognitive functions of the human mind, specifically learning and problem-solving respectively. Within AI a machine learning system identifies patterns within data sets and tries to make predictions based on the data, and a reasoning system solves problems in an ambiguous and changing environment using available knowledge and logical techniques such as deduction and induction. Both machines have direct application in the control of autonomous systems.

The DTP-N improves the aircraft's computer processing power, while the TTNT is a high-capacity data pipe – improving the flow on and off the aircraft. Combined, the two make the aircraft a smart network in the Naval Integrated Fire Control-Counter Air (NIFC-CA) construct.

The three systems enabled two of the Growlers to be operated as unmanned autonomously controlled surrogate aircraft, and the third as a control station; a concept known as manned-unmanned teaming or MUMT. Each surrogate aircraft had a safety pilot on board who performed the take-off and landing.

Jointly funded by NAVAIR and Boeing, the demonstration helped validate technology that enables an EA-18G to fly autonomously as an unmanned electronic attack platform with the ability to operate some of its sensors; in this case the APG-79 AESA radar. According to an official release, the surrogate fighters were flown in multiple pre-set formations and linked air-to-air sensor data [captured by the radar] via TTNT to the manned aircraft.

Given the complex electronic attack and jamming mission performed by the system-laden Growler, this proof-of-concept experiment is likely to be the first step toward further flight trials in which jamming pods and mission systems are operated autonomously.

This probable objective was not mentioned in Boeing's official release, but the company claims the technology used in the demonstration enables the navy to extend the reach of sensors, while keeping manned aircraft out of harm’s way.

Boeing would not confirm if the ARC system is a propriety company product or how long it has been in development, but did confirm the ARC control system used in FLEX 2019 is a separate effort from the Boeing Defence Australia's Airpower Teaming Systems, the so-called loyal wingman concept. Boeing told AIR International that though the two projects may have similar goals regarding manned-unmanned teaming, they are separate efforts.

Despite Boeing's official release stating that ARC could provide synergy with other unmanned systems in development across the warfare spectrum, the company would not confirm that the system is a derivation of that used by its new MQ-25 Stingray unmanned carrier-based aerial-refuelling system.

Over the course of four flights, each involving the three modified Growlers, 21 demonstrations were completed.

Appropriately, Boeing describes the concept as a force multiplier that enables a single aircrew to control multiple aircraft without greatly increasing workload. It seems likely that further application of the concept will be forthcoming to ensure the Growler continues to protect all strike aircraft during even the highest-threat missions.