The Eagle Passive/Active Warning and Survivability System (EPAWSS) for the F-15E redefines electronic warfare with active/passive sensors, autonomous decision-making and integration with existing systems.
Summary
The Eagle Passive/Active Warning and Survivability System (EPAWSS) is the new, unimaginable electronic bulwark for the F-15E Strike Eagle. This system replaces three legacy components (TEWS) to provide an integrated digital suite combining radar warning (RWR), geolocation, active/passive jamming, decoy distribution, and automatic threat management. It autonomously detects, classifies, and locates enemy signals, then decides on the response (jamming, diversion, or neutralisation) based on the threats in a contested electromagnetic space. EPAWSS interfaces with the AN/APG-82(V)1 radar, the mission computer (Core Processor II), and legacy countermeasure systems. In tests, it has demonstrated operational effectiveness and notable cyber resilience, although there is still room for improvement in evolving threat environments. This system represents a strategic advance in extending the relevance of the F-15E in the face of modern defences and competing with the EW capabilities of advanced platforms.
Architecture: passive layer, active layer and countermeasure modules
Passive sensors and radar warning receiver (RWR)
The passive component of EPAWSS acts as a new-generation radar warning receiver (RWR), covering a wide spectrum of RF frequencies. It replaces the TEWS’s older AN/ALR-56C. The system continuously scans the radio environment to detect hostile emissions (tracking radar, missile guidance, surveillance radar). It provides identification and geolocation information on enemy transmitters via triangulation and angle estimation.
The architecture includes low-noise receiver chains, adaptive filters, weak signal detection and signature correlation against a threat library. The module can recognise modern radar modes (AESA, variable frequencies) by comparing the detected characteristics with stored profiles and applying adaptive matching algorithms.
Active jamming and jamming modules
On the active side, EPAWSS incorporates RF jamming modules capable of generating disruptive signals (noise jamming, barrage, DRFM replay, spoofing) to degrade or neutralise enemy radars. These modules are sized to provide sufficient power to compete with enemy radars in contested configurations.
Jamming modes can be modulated, adaptive, and synchronised with flight geometry to maximise effect (directional jamming, nulling, spectral modulation). The system features power allocation control between modules in order to distribute RF resources according to the criticality of the threats detected. The choice of mode (exclusion, jamming, inversion) is determined by the internal decision algorithm.
Distribution of decoys and complementary passive modules
EPAWSS also integrates passive countermeasure management (chaff/flare). It replaces the TEWS’s AN/ALE-45 and adds additional positions: the retrofit increases decoy capacity by 50%, with up to 12 launchers capable of carrying 360 cartridges, distributed in specific fairings behind the tail fins.
The system can automatically trigger decoys or deploy them in coordination with jamming when a radar or infrared missile threat is detected. It can also synchronise decoys with active modules to maximise confusion of the enemy system.
Autonomous decision-making: detection, classification and automatic response
Detection and classification logic
EPAWSS operates as an autonomous system, capable of detecting an unknown emission, extracting its characteristics (frequency, band, modulation, amplitude, direction) and then comparing it to the threat library. If the emission corresponds to a known radar (missile guidance, tracking, surveillance), the system classifies the threat, assesses it according to its priority (surface vs air, active vs passive) and calculates the level of danger.
It performs this classification in real time, using correlation algorithms, machine learning (cognitive EW) to recognise new, unclassified sources, and adaptive expansion — i.e. generating hypothetical signatures for partial matches.
Decision-making and response
Once the threat has been identified, the system decides on the type of response: do nothing, jamming, decoys, diversionary countermeasures, change of course. The EPAWSS calculator weighs up the costs (energy consumption, interference with its own sensors, risk of over-compromise) against the benefits (protection of the aircraft).
The system can even automatically trigger jamming or decoys if a missile radar is deemed imminent, without pilot intervention, while providing a user interface for supervision. Pilots receive alerts, the geolocated position of the threat and a recommendation or automatic response command.
In multiple threat contexts, EPAWSS prioritises defence according to severity, proximity or angle. It can switch between modes, distribute power between multiple targets or concentrate directional jamming on the most dangerous threat.
Integration with existing systems and data flows
Substitution and integration of TEWS components
EPAWSS replaces three TEWS components: the AN/ALR-56C RWR, the AN/ALQ-135 internal jamming, and the AN/ALE-45 Dispenser Set. This consolidation simplifies wiring, reduces redundancy, and creates a more consistent native EW layer.
Integration with the AN/APG-82(V)1 radar, via the Core Processor II mission computer, is essential: the radar shares tracking, angle, and threat status data with EPAWSS to improve signal correlation. EPAWSS can also influence the radar (change modes, block certain frequencies) according to jamming requirements.
Data bus and system architecture
The system is based on an open architecture (Open Systems Architecture) to facilitate software updates and the addition of modules. Data flows pass through high-speed buses (e.g. CNI, avionics data buses) with QoS prioritisation so that EW alerts and decisions benefit from minimal latency.
The components (sensors, processors, actuators) are distributed spatially throughout the aircraft and communicate via redundant networks. Jamming or decoy modules are connected via high-speed interfaces for real-time acquisition or control.
During testing, some false positives were observed in the built-in tests (BITs) — this implies a refinement in the management of on-board diagnostics. The Mission Data File (MDF) generator, which compiles threat parameters in the system, was found to be slow in this regard, and an improvement is expected. The DOT&E noted 20 MDF generation deficiencies in an evaluation report. (test range)
Performance, metrics and known limitations
Test results and measured effectiveness
In IOT&E tests between 2023 and 2024, the EPAWSS system was assessed as operationally effective, suitable and cyber-survivable in the environments tested. However, its effectiveness against evolving threats was not fully measured due to limitations of the test environment. The DOT&E reports a lack of comparative effectiveness data without EPAWSS.
During test missions, defensive and offensive flights were conducted against simulated 4th and 5th generation aircraft. The threat geolocation and radar warning capabilities were approved. However, Electronic Attack (EA) measures were not fully verified due to the limited representation of threats on the test fields. (DOT&E FY2024)
Cyber resilience and robustness
The system withstood cyber attack emulation tests (injection, disruption) during IOT&E without suffering any major effects. It is therefore considered cyber survivable in the tested scenario. Nevertheless, in an environment literally saturated with RF counterfeits, spoofing and cyber attacks, there may still be vulnerabilities to explore.
Weaknesses identified include: BIT and false alarms, slow generation and updating of MDFs, and the challenge of fully modelling emerging threats.
Electromagnetic Key Performance Indicators (KPIs)
To evaluate an EW system such as EPAWSS, a few common metrics apply:
- EW Figure of Merit (FOM): ratio of effective jamming power to enemy radar transmission power, adjusted for distance and propagation.
- Probability of suppressing an enemy radar (Se)
- Confusion factor gain (the system’s ability to mislead the radar towards false targets)
- Reaction time (latency between detection and response)
- Resilience to adversarial jamming: ability to resist adversarial countermeasures (anti-jamming, nulling)
- Alignment against internal cyber/RF attacks
- False alarm rate & missed detection rate
Public reports state that the DOT&E noted progress in reducing false alarms during final testing, which improves operational reliability.
Deployment, industrial challenges and future prospects
Adoption and timeline
The first F-15E equipped with EPAWSS was delivered to the Royal Air Force at Lakenheath in January 2025, as part of the 48th Fighter Wing. (RAF Lakenheath)
The USAF plans to upgrade up to 99 F-15E Strike Eagles and equip all F-15EXs with this EW suite.
A $615.8 million contract was awarded for full-rate production, providing Group A (support) and B (main modules) kits. (full-rate contract)
Despite progress, the programme is suffering from supply chain issues: some parts are ‘diminishing manufacturing sources’ (DMS), making planning more complex. The GAO has highlighted risks of installation on legacy aircraft and potential delays.
Technical and industrial challenges
- Integrating EPAWSS into older aircraft requires structural reinforcements (modified tail beams, external antennas) to accommodate the new modules and decoys.
- The DMS supply chain requires anticipating obsolescence and using a modular architecture to facilitate future replacements.
- The MDF (Mission Data File) software must be optimised to be faster, more flexible and easier for operators to use.
- Testing in highly contested real-world environments is limited; the difficulty lies in credibly simulating emerging threats (AESA, advanced EW, cognitive warfare) in a test range.
- Scalability is highly desirable: BAE is already working on EPAWSS v2, which will provide increased processing power, broader simultaneous threat management, and likely hardware improvements to anticipate future RF threats.
Strategic and competitive impact
EPAWSS transforms a 4th generation F-15E into a 4.5th generation platform, capable of penetrating modern air defences thanks to its integrated EW arsenal.
In a context where several military forces are investing in electromagnetic warfare (Russia, China, regional powers), EPAWSS offers the USAF a tool for deterrence and superiority in the EM spectrum.
The competition lies in pure EW platforms (EA-18G Growler), but EPAWSS allows a strike fighter to have native self-protection without resorting to external pods for intersecting missions.
Ultimately, an F-15E/EPAWSS could serve as a formation leader, drone orchestrator or electromagnetic strike mission director, exploiting its EW capability to support other vectors.
With EPAWSS, the F-15E Strike Eagle enters a new dimension: one where the electromagnetic spectrum becomes as crucial a weapon as missiles. This system modernises the defensive and offensive roles of this fighter in contested environments. The challenges are numerous — industrialisation, shifting threats, realistic testing — but the benefits are clear: a strike aircraft capable of surviving in a saturated theatre without relying on external EW assets. This effort positions the F-15E (and its successor, the EX) as a credible player in 21st-century conflicts.
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