The Legion Pod flew for the first time on an F-15C in 2016 and the following year the Air Force selected the Lockheed Martin system over Northrop Grumman’s Open Pod. Boeing was subsequently awarded a contract by the USAF to integrate the pod onto the F-15C, including $154.6 million for engineering, manufacturing, and development work, plus production, integration, test, and deployment. A total of around 130 pods were planned to equip the F-15C fleet.
As of November 2018, the Air Force’s plan was to reach initial operational capability with the system on the F-15C in 2020. In May 2019, a picture emerged showing an F-15C from the 57th Wing at Nellis Air Force Base carrying a Legion Pod during the U.S. military’s biannual Northern Edge exercise in Alaska, an advanced integration event.
The Legion Pod is fitted with Lockheed Martin’s AN/ASG-34 infra-red search-and-track (IRST) sensor, which can locate and track targets at long range. It also provides targeting information to enable the pilot to engage threats using the IRST alone, or in combination with other sensors, which provides a robust capability in all situations. This is particularly effective in dense electronic warfare (jamming) combat environments. Unlike a traditional radar, the IRST operates passively putting out no electronic emissions, which means it also reduces the risk of alerting potential opponents that they are being targeted.
Legion Pod is actually a modular pod system that can accommodate additional payloads in the future, as well as the IRST in its front end. As such, it could offer an easy way to bring new capabilities to the aircraft that carry it, such as communications gateways, electronic warfare systems, or even other sensors.
In recent years, the USAF F-15Cs have started carrying Lockheed Martin’s AN/AAQ-33 Sniper Advanced Targeting Pod (ATP) on the aircraft’s centerline station. This is primarily used for long-range visual identification of targets, day or night. The Sniper pod primarily finds its targets by slaving its optics to the F-15C’s AN/APG-63V3 radar. The pilot can also manually steer the Sniper pod or cue it to their Joint Helmet Mounted Cueing System (JHMCS), but it is far less capable when it comes to searching for and providing targeting data in the air-to-air regime compared to the Legion Pod’s IRST.
Lockheed Martin has also developed the IRST21 sensor, which was based on the earlier AN/AAS-42 IRST system that was fitted to the F-14D Tomcat. Another version of that system, known as Tiger Eyes, is now featured on export versions of the F-15 Strike Eagle and Advanced F-15 Eagle.
IRST21 is being fielded by the U.S. Navy on its Block III F/A-18E/F Super Hornet, as well, and it reflects growing popularity of IRST carriage on 4th generation fighter platforms in U.S. military service. For more detail on how IRSTs are employed and why they have become so important to modern fighter aircraft, click here, but in this case, using the IRST with the AIM-9X signifies a big capability boost.
A fighter equipped with the IRST carrying Legion Pod and an AIM-9X can hunt and kill targets, even just beyond visual range, in a largely electromagnetically silent state. It can do this while also leveraging the maximum efficiency of the AIM-9X Block II. The targeted aircraft wouldn’t be alerted as to the incoming missile presence even during its terminal stage of flight because the AIM-9X uses an imaging infrared sensor (IIR), which is also passive. As such, IRST and AIM-9X together are one heck of a ‘hunter-killer’ team.
These types of tactical opportunities are just another reason why advanced IRSTs are becoming absolutely critical kit on fighter aircraft.
Contact the author: Jamie@thedrive.com