Support Equipment

IRST21 Sensor System

Also known as
  • IRST21
  • IRST 21
  • IRST Block II
  • IRST21 Block II
  • Legion Pod
  • Legion-ES
  • Infrared Search and Track 21

IRST21 is Lockheed Martin's passive long-wave infrared search-and-track sensor family for fighter aircraft, packaged either inside the F/A-18E/F Super Hornet centerline tank or in the modular Legion Pod. It gives aircraft a non-emitting air-to-air detection and tracking channel, has supported F-15C missile-cue testing with AIM-9X and AIM-120 shots, and moved into Navy IRST Block II fielding for the Super Hornet in 2025.

IRST21 Sensor System, Passive long-wave infrared search-and-track sensor system, Support Equipment
Image source: IRST21 IOC for F/A-18E/F
Profile / Specs

Profile

Origin
United States
Type
Passive long-wave infrared search-and-track sensor system
Service note
2010s-present
Produced
2010s-present

Specifications

Sensor type
Long-wave infrared search-and-track
Operating mode
Passive; detects and tracks without emitting radar energy
F/A-18E/F installation
Integrated in the front of the Super Hornet centerline fuel tank
Legion Pod structure
16-inch-diameter self-contained pod package
Legion Pod baseline equipment
IRST21 sensor, advanced processor, networking, and datalink capability
Documented missile cueing
F-15C Legion Pod test events supported AIM-9X and AIM-120 shots
Mission
Detects and tracks airborne threats at extended range
What The Sensor Adds
CapabilityCatalog meaningSource-backed example
Passive search and trackThe sensor gives an aircraft a detection channel that does not advertise itself like radar emission.Lockheed Martin describes IRST21 as a passive long-wave infrared search-and-track system.
Podded transferabilityLegion Pod moves the IRST21 package across aircraft without tying the sensor to one airframe integration.Lockheed Martin describes a self-contained 16-inch pod with sensor, processor, networking, and datalink hardware.
Air-to-air cueingThe component matters to weapon employment because it can contribute target tracks for missile shots.Air Combat Command reported F-15C IRST-assisted AIM-9X and AIM-120 live-fire test events.
Variants

IRST21 appears in aircraft-specific installations and podded configurations rather than as a single airframe-locked sensor package.

VariantConfigurationDesignation notes
Super Hornet centerline-tank installationF/A-18E/F Super Hornet tank installation

The Navy IOC release and later full-rate production contract identify IRST Block II as the Super Hornet installation integrated in the aircraft's centerline fuel tank.

Sources: IRST21 IOC for F/A-18E/F, IRST Block II Full-Rate Production Contract

Podded multi-function sensor packagePodded multi-function sensor system

Lockheed Martin describes Legion Pod as a self-contained pod using IRST21 sensor, networking, and processing technology for fighter and non-fighter aircraft.

Sources: Legion Pod, Legion Pod wins F-15C IRST Competition

IRST Block 1.5F-15C Legion Pod fielding configuration

Air Combat Command reported F-15C Legion Pod IOC under the IRST Block 1.5 program, following operational test and live-fire events.

Sources: Legion Pod reaches Initial Operating Capability

IRST21 Legion-ESEmbedded F-16 configuration

Lockheed Martin's 2026 Foreign Military Sales contract release identifies Legion-ES as an embedded IRST21 configuration supporting Taiwan F-16 aircraft.

Sources: IRST21 Legion-ES Foreign Military Sales Contract

Aircraft Integrations

IRST21 is documented in both embedded Super Hornet installations and podded Legion Pod configurations for tactical aircraft.

Compatible itemItem typeCompatibility evidence
F/A-18E/F Super Hornet, Carrier-capable multirole strike fighter, Aircraft & UAVsF/A-18E/F Super HornetCarrier-capable strike fighter

The Navy's 2025 IRST21 IOC system is integrated in the front of the F/A-18E/F Super Hornet centerline fuel tank.

Sources: IRST21 IOC for F/A-18E/F, IRST Block II Full-Rate Production Contract

F-15 family fighter aircraft, Fighter aircraft family, Aircraft & UAVsF-15 family fighter aircraftFighter aircraft family

Legion Pod was selected for the F-15C IRST competition, and Air Combat Command later reported F-15C Legion Pod initial operating capability.

Sources: Legion Pod wins F-15C IRST Competition, Legion Pod reaches Initial Operating Capability

F-15EX Eagle II, Multirole fighter aircraft, Aircraft & UAVsF-15EX Eagle IIFighter aircraft

Air Combat Command described Legion Pod as the IRST capability for the F-15C and F-15EX when reporting F-15C IOC.

Sources: Legion Pod reaches Initial Operating Capability

F-16 Fighting Falcon, Multirole fighter aircraft, Aircraft & UAVsF-16 Fighting FalconMultirole fighter

Lockheed Martin and later FMS contract reporting identify Legion Pod and Legion-ES work tied to F-16 aircraft.

Sources: Legion Pod, IRST21 Legion-ES Foreign Military Sales Contract

Component-page sourcing limit

The sources support integration, production, test, and fielding context for the sensor system; they do not independently document IRST21 or Legion Pod use in a named armed conflict.

Sources: IRST21 Sensor System, Legion Pod reaches Initial Operating Capability

Missile Cueing Context

The F-15C test lane links Legion Pod to infrared-search-and-track-assisted air-to-air missile employment.

Compatible itemItem typeCompatibility evidence
AIM-9X Sidewinder missile, Short-range air-to-air missile, MunitionsAIM-9X Sidewinder missileShort-range air-to-air missile

Air Combat Command reported an F-15C first AIM-9X live-fire event from Legion Pod during the IRST test program.

Sources: Legion Pod reaches two flight milestones

AIM-120 AMRAAM, Beyond-visual-range air-to-air missile, MunitionsAIM-120 AMRAAMBeyond-visual-range air-to-air missile

Air Combat Command reported an F-15C AIM-120 shot cued by the infrared search-and-track system during a test against a QF-16 drone target.

Sources: F-15 Puts Tracking-System-Assisted Missile on Target

Integration Status

The record is strongest as a component page because public sources document integration, production, and test activity rather than independent conflict use.

ConfigurationAircraft linkDocumented status
IRST21 Block IIF/A-18E/F Super Hornet, Carrier-capable multirole strike fighter, Aircraft & UAVsF/A-18E/F Super HornetNavy IOC announced in 2025, followed by a full-rate production contract for Super Hornet centerline-tank installations.
Legion Pod / IRST Block 1.5F-15 family fighter aircraft, Fighter aircraft family, Aircraft & UAVsF-15 family fighter aircraftSelected for F-15C IRST, then reported at initial operating capability by Air Combat Command in 2022.
Legion PodF-16 Fighting Falcon, Multirole fighter aircraft, Aircraft & UAVsF-16 Fighting FalconLockheed Martin describes flight-test and cross-platform pod packaging; its official video shows Legion Pod on an F-16.
IRST21 Legion-ESF-16 Fighting Falcon, Multirole fighter aircraft, Aircraft & UAVsF-16 Fighting FalconForeign Military Sales contract reporting identifies an embedded IRST21 configuration for Taiwan F-16 aircraft.
Timeline

IRST21 Sensor System Key Events

  1. Legion Pod selected for F-15C IRST

    Lockheed Martin announced that Legion Pod had won the F-15C IRST competition and described prior F-15C and F-16 flight-test work.

    Sources: Legion Pod wins F-15C IRST Competition

  2. First Legion Pod AIM-9X shot

    Air Force reporting said an F-15C fired an AIM-9X using Legion Pod on July 8, 2020, and an F-16 made its first operational flight with the pod five days later.

    Sources: Legion Pod reaches two flight milestones

  3. IRST-cued AIM-120 target shot

    Air Combat Command reporting says an F-15C with Legion Pod IRST Block 1.5 used IRST-assisted cueing in an AIM-120 shot against a QF-16 aerial target.

    Sources: F-15 Puts Tracking-System-Assisted Missile on Target

  4. F-15C Legion Pod reaches IOC

    Air Combat Command reported initial operating capability for Legion Pod on the F-15C under the IRST Block 1.5 program.

    Sources: Legion Pod reaches Initial Operating Capability

  5. Super Hornet IRST21 IOC announced

    Lockheed Martin announced Navy initial operational capability for next-generation IRST21 sensors on the F/A-18E/F Super Hornet.

    Sources: IRST21 IOC for F/A-18E/F

  6. IRST Block II full-rate production contract

    Lockheed Martin announced a $233 million Navy contract for full-rate production IRST Block II systems for the Super Hornet.

    Sources: IRST Block II Full-Rate Production Contract

  7. Legion-ES FMS contract announced

    Lockheed Martin announced a $328.5 million Foreign Military Sales contract for IRST21 Legion-ES to support Taiwan F-16 aircraft.

    Sources: IRST21 Legion-ES Foreign Military Sales Contract

Media

IRST21 Sensor System Videos

IRST21 Sensor System Images

IRST21 Sensor System, Passive long-wave infrared search-and-track sensor system, Support Equipment - view 1
Source: IRST21 IOC for F/A-18E/F
Related Weapon Systems
F/A-18E/F Super Hornet, Carrier-capable multirole strike fighter, Aircraft & UAVsAircraft & UAVsF/A-18E/F Super HornetCarrier-capable multirole strike fighterBoeing's F/A-18E/F Super Hornet is a U.S. Navy carrier-capable multirole strike fighter developed from the Hornet family for fleet air defense, escort, interdiction, close air support, aerial refueling, suppression of enemy air defenses, and day/night precision strike. The single-seat F/A-18E and two-seat F/A-18F anchor carrier air wings through Block II and Block III upgrades, with documented U.S. Navy use in Afghanistan drawdown support, Operation Inherent Resolve, the Red Sea crisis, Somalia strikes, and U.S. operations against Iran.
Lockheed Martin F-21, Multirole fighter aircraft proposal, Aircraft & UAVsAircraft & UAVsLockheed Martin F-21Multirole fighter aircraft proposalThe Lockheed Martin F-21 is an India-specific multirole fighter proposal based on the F-16 Block 70/72 and marketed for the Indian Air Force's MRFA requirement. Lockheed and Tata framed the bid around Indian production, F-16 wing work at Hyderabad, and an aircraft configuration with conformal fuel tanks, a large-area cockpit display, APG-83-class AESA radar, probe-and-drogue plus boom refueling compatibility, and promotional carriage of AMRAAM, AIM-9X, Sniper pod, and AN/ALE-50 stores.
IRIS-T, Short-range air-to-air missile, MunitionsMunitionsIRIS-TShort-range air-to-air missileIRIS-T is a short-range imaging-infrared air-to-air missile developed through a European cooperation program with Diehl Defence as prime contractor. The missile is integrated with fighters including Eurofighter/Typhoon, Gripen, F-16, Tornado, EF-18, KF-21, and F-5E; Reuters reporting also documents Saudi Eurofighters using IRIS-T against drones fired from Houthi-controlled Yemen. Diehl describes the same air-to-air missile hardware as the effector in the short-range IRIS-T SLS ground-based air-defense system.
F-35 Electro Optical Targeting System (EOTS), Internally mounted electro-optical targeting sensor subsystem, Support EquipmentSupport EquipmentF-35 Electro Optical Targeting System (EOTS)Internally mounted electro-optical targeting sensor subsystemThe F-35 Electro Optical Targeting System (EOTS) is the AN/AAQ-40 sensor installation built into the F-35 Lightning II for precision air-to-air and air-to-surface targeting. Lockheed Martin describes it as a low-observable, internally mounted system that combines forward-looking infrared and infrared-search-and-track functions, and Janes reported F-35I EOTS footage from an Israeli cruise-missile interception during the 2023 Israel-Hamas War.
Space-Based Infrared System / SBIRS, Missile-warning satellite constellation, Support EquipmentSupport EquipmentSpace-Based Infrared System / SBIRSMissile-warning satellite constellationSpace-Based Infrared System (SBIRS) is the U.S. Space Force space-based missile-warning constellation that replaced Defense Support Program coverage with geosynchronous satellites, highly elliptical orbit payloads, and consolidated ground processing. Lockheed Martin led the space and ground system, Northrop Grumman supplied infrared payloads, and official reporting says SBIRS provided early warning during Iran's April 2024 missile and drone attack on Israel.

Sources

IRST21 Sensor SystemPublisher: Lockheed Martin | Note: Supports IRST21 background, manufacturer context, passive long-wave infrared search-and-track role, and general system description. | Accessed: 2026-06-29IRST21 IOC for F/A-18E/FPublisher: Lockheed Martin | Note: Supports the F/A-18E/F integration, Navy IOC context, passive long-wave infrared role, centerline fuel tank installation, extended-range detection and tracking, and image provenance for the release photo. | Accessed: 2026-06-29Legion PodPublisher: Lockheed Martin | Note: Supports Legion Pod packaging, modular pod context, 16-inch pod structure, processor and datalink context, and cross-platform fighter-aircraft integration of IRST21. | Accessed: 2026-06-29Legion Pod wins F-15C IRST CompetitionPublisher: Lockheed Martin | Note: Supports F-15C compatibility, long-range detection and tracking claims, Legion Pod flight-test context, F-16 and F-15C test context, and image provenance for the infographic. | Accessed: 2026-06-29Legion Pod reaches two flight milestonesPublisher: Air Force Life Cycle Management Center | Note: Supports F-15C Legion Pod AIM-9X test activity and F-16 first operational flight context for the IRST program. | Accessed: 2026-06-29F-15 Puts Tracking-System-Assisted Missile on TargetPublisher: Air Combat Command | Note: Supports F-15C IRST-assisted AIM-120 live-fire test context against a QF-16 drone target. | Accessed: 2026-06-29Legion Pod reaches Initial Operating CapabilityPublisher: Air Combat Command | Note: Supports F-15C Legion Pod initial operating capability, IRST Block 1.5 designation context, and F-15C/F-15EX fielding relevance. | Accessed: 2026-06-29IRST Block II Full-Rate Production ContractPublisher: Lockheed Martin | Note: Supports Navy full-rate production contract context for IRST Block II systems on the F/A-18E/F Super Hornet. | Accessed: 2026-06-29IRST21 Legion-ES Foreign Military Sales ContractPublisher: Lockheed Martin | Note: Supports IRST21 Legion-ES configuration context and Foreign Military Sales support for Taiwan F-16 aircraft. | Accessed: 2026-06-29