Looking at modern fighter aircraft, IRST and FLIR systems have become absolutely critical for beyond-visual-range combat and networked warfare. These sophisticated sensors work by detecting the heat signatures that all aircraft emit, giving pilots a way to find and track targets without using radar - which means they can hunt without being detected themselves.
Understanding the Core Technology
IRST systems are essentially advanced thermal cameras that can spot the infrared radiation from aircraft engines, hot surfaces, and even the friction heat generated by high-speed flight. Unlike radar systems that broadcast signals, IRST operates completely passively, making it nearly impossible for enemies to detect that they're being tracked. FLIR systems serve similar purposes but are often optimized for detailed imaging and multi-role applications.
1. Core Technology: Passive Infrared Detection
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IRST systems operate based on infrared (IR) detection, specifically in the mid-wave (3–5 µm) or long-wave (8–12 µm) infrared bands.
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They are passive electro-optical systems: they do not emit any signals, unlike radars which are active and emit electromagnetic waves.
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This passive nature makes IRST stealthy—the system only receives IR radiation, mostly thermal emissions from jet engines, heated airframe surfaces, and sometimes aerodynamic heating at high speeds.
2. IRST vs FLIR: Functional Differences
3. Tactical Role in Air Combat
4. Within Visual Range (WVR) Dogfighting
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In WVR combat, radar use becomes a liability:
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Pilots using IRST maintain situational awareness (SA) of multiple airborne threats or friendly units without lighting up their radar.
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This is crucial for ambush tactics, defensive maneuvering, or silent interception.
5. Limitations and Mitigation
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Range and Accuracy: IRST range is typically shorter than radar, especially in humid or cloudy conditions which attenuate IR signals.
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Range Finding: Since IRST is passive, it cannot determine range directly like radar can.
The real game-changer is how these systems integrate with modern data networks. When an aircraft detects a target through its IRST, it can share that information instantly with other friendly aircraft, creating a distributed sensor network that's incredibly difficult to counter.
Aircraft-Specific Systems and Capabilities
F-35 Lightning II - The Complete Package
The F-35 represents the pinnacle of integrated infrared technology. The aircraft combines the AN/AAQ-40 Electro-Optical Targeting System (EOTS) with the revolutionary Distributed Aperture System (DAS), which includes six infrared cameras placed around the aircraft providing 360-degree coverage. The Advanced EOTS incorporates short-wave infrared, high-definition television, an infrared marker, and improved image detector resolution to increase pilot recognition and detection ranges.
What makes the F-35 unique is how this infrared data integrates with its helmet-mounted display system. Pilots can literally see "through" their aircraft and engage targets at extreme off-boresight angles. For BVR missile engagements, the F-35 can detect targets passively through IRST, calculate firing solutions, and share targeting data through its advanced Multi-Function Advanced Data Link (MADL) with other F-35s, or through Link 16 with other NATO aircraft.
The DAS system uses six high-resolution infrared sensors distributed around the aircraft's fuselage. Each sensor contains a 1024x1024 focal plane array operating in the mid-wave infrared spectrum (3-5 micrometers). The system processes over 40 million pixels per second, creating a seamless spherical view around the aircraft. This data gets fused with other sensors through the aircraft's central computer system running at over 400 billion operations per second.
F/A-18E/F Super Hornet - Modular Excellence
The Super Hornet employs the AN/ASQ-228 ATFLIR (Advanced Targeting FLIR) pod, which can locate and designate targets day or night at ranges exceeding 40 nautical miles and altitudes surpassing 50,000 feet. The Navy has also recently achieved Initial Operational Capability for IRST pods on Super Hornets, adding dedicated air-to-air infrared search capabilities.
The ATFLIR system's strength lies in its networking capabilities. As a powerful net-enabler, it can pass tracking and targeting information to other nodes in the networked battlespace. This means a Super Hornet can detect targets through its infrared sensors and immediately share precise targeting coordinates with other aircraft for cooperative BVR engagements using AMRAAM or other long-range missiles.
The ATFLIR pod uses a third-generation, 640x512 indium antimonide focal plane array cooled to cryogenic temperatures. It operates in both mid-wave (3-5 μm) and long-wave (8-12 μm) infrared spectrums, with the ability to switch between narrow and wide field-of-view modes. The pod's laser designator operates at 1.064 micrometers with a pulse repetition frequency that can be varied to avoid countermeasures.
F-16 Fighting Falcon - Adaptive Hunter
The F-16 has evolved to use external IRST pods, particularly the Legion Pod system. F-16s equipped with datalink-enabled Legion Pods can share tracks with other aircraft like F/A-18E/F Super Hornets, and can use the pod's IRST21 infrared sensor to passively triangulate target positions. The aircraft can share sensor data over the Legion pod's Advanced Datalink to passively triangulate target position without using radar or other active ranging sources.
This capability transforms the F-16 into a highly effective BVR platform. Multiple F-16s can work together, using their IRST systems to triangulate targets and coordinate missile launches while remaining electronically silent.
The Legion Pod houses the IRST21 sensor, which uses a mercury-cadmium-telluride detector array operating in the 3-5 micrometer waveband. The system can detect jet engine exhaust signatures at ranges exceeding 50 kilometers under optimal conditions. The pod's onboard processor can track up to 200 targets simultaneously while maintaining search patterns across a 90-degree azimuth and 60-degree elevation field of regard.
Rafale - Integrated Elegance
The French Rafale uses the OSF (Optronique Secteur Frontal) system, which combines infrared search/track and television channels in a single, elegant installation. The system is linked to the targeting system, making it capable of guiding MICA missiles to targets, essentially functioning as a second radar system and providing a potential answer to stealth aircraft.
The Rafale's strength is the tight integration between its OSF system and the aircraft's overall sensor fusion architecture. This allows for seamless transitions between radar and infrared targeting, giving pilots multiple ways to engage BVR targets while sharing data through NATO-standard Link 16 datalinks.
The OSF system incorporates a cooled infrared detector operating in the 3-12 micrometer spectrum with a 140-degree horizontal field of regard. The system can automatically detect and track multiple targets while providing accurate range measurements using laser ranging up to 40 kilometers. Its television channel operates in visible and near-infrared spectrums with magnification capabilities up to 12x.
Eurofighter Typhoon - Purpose-Built Air Superiority
The Eurofighter Typhoon features PIRATE (Passive InfraRed Airborne Track Equipment), developed through a Leonardo-led consortium and designed specifically for air superiority missions. PIRATE detects infrared signatures of aircraft at long range over a wide field of view under all conditions of visibility.
PIRATE's integration with the Typhoon's CAPTOR radar creates a formidable sensor combination. The system can hand off targets between radar and infrared modes seamlessly, and share targeting data through the aircraft's advanced datalinks for coordinated BVR attacks using Meteor or AMRAAM missiles.
The PIRATE system uses a mercury-cadmium-telluride focal plane array cooled by a closed-cycle Stirling cooler. Operating in the 8-12 micrometer long-wave infrared band, it can detect targets at ranges up to 90 kilometers in clear conditions. The system scans a 90-degree azimuth sector and can track multiple targets while maintaining search functions.
JF-17 Thunder and J-10 - Emerging Capabilities
Both Pakistani and Chinese fighters incorporate indigenous IRST systems that reflect growing expertise in infrared technology. The JF-17's integrated IRST provides cost-effective BVR detection capabilities, while the J-10's forward-mounted infrared systems offer similar functionality. These aircraft can use their IRST systems to guide SD-10 or PL-15 missiles in BVR engagements, with data sharing capabilities through Chinese-developed datalinks.
The JF-17's IRST system uses Chinese-developed infrared detectors operating in the 3-5 micrometer band. The system can detect fighter-sized targets at ranges of approximately 40-50 kilometers and integrates with the aircraft's KLJ-7 radar through the central mission computer. Data sharing occurs through the aircraft's indigenous datalink system, which is compatible with Chinese air defense networks.
The J-10's IRST system employs more advanced infrared technology with detection ranges reportedly exceeding 60 kilometers for fighter-sized targets. The system integrates seamlessly with the aircraft's pulse-Doppler radar and can provide targeting data for beyond-visual-range missiles through secure Chinese military datalinks.
Gripen - Swedish Efficiency
The Gripen employs the Skyward-G IRST system, which exemplifies Swedish design philosophy of maximum capability in a compact, efficient package. The system integrates seamlessly with the aircraft's overall sensor suite and can coordinate BVR attacks using AMRAAM or Meteor missiles while sharing data through Link 16.
The Skyward-G system uses a third-generation infrared focal plane array with 640x512 resolution operating in the 8-12 micrometer spectrum. Despite its compact size, the system can detect targets at ranges comparable to much larger systems, demonstrating Swedish expertise in miniaturization and efficiency.
Su-30MKI - Russian Heritage
The Su-30MKI features the OLS-30 infrared search and track system, representing decades of Russian experience with IRST technology. The system offers impressive detection ranges and integrates with the aircraft's powerful radar systems. For BVR engagements, the Su-30MKI can use its IRST to guide R-77 or R-27 missiles while sharing targeting data through Russian datalink systems.
The OLS-30 system combines infrared search and track with laser ranging capabilities. Using a cooled mercury-cadmium-telluride detector operating in the 8-12 micrometer band, it can detect fighter aircraft at ranges up to 90 kilometers and helicopters at 20 kilometers. The laser rangefinder operates at 1.54 micrometers with a maximum range of 3.5 kilometers.
BVR Missile Integration and Data Sharing
The real revolution in modern air combat is how these IRST systems enable cooperative targeting. Aircraft can now operate in "emission control" mode, using only passive infrared sensors to detect targets while sharing information through secure datalinks. This creates a distributed sensor network where multiple aircraft can collaborate to engage targets that no single aircraft might be able to handle alone.
Recent tests have proven that aircraft equipped with advanced IRST systems can passively triangulate target positions and coordinate attacks, fundamentally changing how BVR combat operates. The ability to detect, track, and engage targets without emitting any radar signals provides an enormous tactical advantage, especially against stealth aircraft that rely on low radar cross-sections for protection.
Modern datalink systems enable real-time sharing of IRST-derived targeting data. For example, multiple F-16s with Legion Pods can detect a target through their individual IRST systems, then use triangulation algorithms to determine precise target location and velocity. This data gets automatically shared through secure datalinks, allowing any aircraft in the network to launch BVR missiles even if they haven't directly detected the target themselves.
The integration with modern missiles is equally sophisticated. Advanced missiles like the AIM-120D AMRAAM, Meteor, and PL-15 can receive mid-course updates from IRST-equipped aircraft, allowing them to engage targets that were initially detected through infrared sensors rather than radar. This capability is particularly valuable against stealth targets that might be difficult to detect with radar but still emit infrared signatures.
Modern IRST systems have transformed from simple detection devices into integral components of networked warfare, enabling new tactics and strategies that weren't possible just a decade ago. As these systems continue to evolve, they're becoming essential tools for maintaining air superiority in increasingly complex threat environments.
References
- Lockheed Martin F-35 Lightning II EOTS specifications, Lockheed Martin official documentation
- Defense Update: Lockheed Martin Prepared to Enhance F-35 Targeting Capability, September 2019
- Air Force Technology: Lockheed Martin continues developing Advanced EOTS for F-35, September 2019
- Simple Flying: What Is The EOTS In The F-35 Lightning II?, February 2025
- The War Zone: Legion Infrared Search And Track Pods Can Now Carry Their Own Datalinks For More Lethal Targeting, June 2021
- The Aviation Geek Club: USAF proved F-15 and F-16 Legion Pod triangulation capabilities, April 2022
- Air & Space Forces Magazine: F-15 and F-16 Jointly Test Legion Pod Infrared Tracker, April 2022
- The Aviation Geek Club: US Navy Looks to Replace or Improve F/A-18 Super Hornet's ATFLIR Targeting Pod, March 2020
- The National Interest: The Navy's Super Hornet Is Getting Better at Killing Its Enemies, February 2018
- Global Defence Technology: Infrared search and track technology gives fighter aircraft stealth vision, February 2019
- The Aviationist: U.S. Navy Declares Initial Operational Capability for IRST Pods on F/A-18 Super Hornets, February 2025