Lockheed Martin has received a new full-rate production contract, valued at $233 million, for Block II IRST21 infrared search and track sensors to go into pods for U.S. Navy and U.S. Air National Guard fighters. For the Navy, in particular, this is a notable move forward given the reliability and quality control issues the service has faced with its podded configuration of the IRST21 for years now.
The Navy officially declared initial operational capability (IOC) with its version of the IRST21, also known by the designation AN/ASG-34A(V)1, back in November 2024. Limited operational evaluations, including as part combat operations in the Middle East, had been ongoing since at least 2020.
The Navy’s pod, developed for use on the service’s the F/A-18E/F Super Hornets consists of a modified FPU-13/A drop tank with the IRST sensor in a redesigned front section, as you can learn about more in this past TWZ feature. Air Force F-15C/D Eagles, which are now in the process of being retired, and F-16C/D Vipers, have been flying for years with IRST21s integrated into modular, multi-purpose Legion Pods from Lockheed Martin. Legion Pods with IRST21s are part of the sensor suite for the Air Force’s new F-15EX Eagle IIs, as well. Though they have the same IRST sensor at their core, which allows for shared contracts like the one announced today, the Navy and Air Force efforts are distinct, with major differences in the respective pod designs.
The Navy’s pod, developed for use on the service’s the F/A-18E/F Super Hornets consists of a modified FPU-13/A drop tank with the IRST sensor in a redesigned front section, as you can learn about more in this past TWZ feature. Air Force F-15C/D Eagles, which are now in the process of being retired, and F-16C/D Vipers, have been flying for years with IRST21s integrated into modular, multi-purpose Legion Pods from Lockheed Martin. Legion Pods with IRST21s are part of the sensor suite for the Air Force’s new F-15EX Eagle IIs, as well.
As designed, the ASG-34A(V)1 has long been set to offer a valuable new way for Navy Super Hornets to spot and track airborne threats. IRST systems offer particular advantages when it comes to detecting stealthy crewed and uncrewed aircraft, as well as missiles, designed to evade traditional radars. IRSTs also scan passively, so they do not send out signals that can alert an opponent to the fact that they are being tracked, and are also immune to expanding adversary electronic warfare capabilities. The information from IRSTs can also be fuzed with that from radars, datalinks, and other passive sensors to provide major synergistic capabilities.
When carried by a Super Hornet, “the IRST acts as a complementary sensor to the aircraft’s AN/APG-79 fire control radar in a heavy electronic attack or radar-denied environment,” according to the Pentagon’s Office of the Director of Test and Evaluation. “It operates autonomously, or in combination with other sensors, to support the guidance of beyond-visual-range air-to-air missiles.”
IRST systems, in general, have experienced a renaissance within the U.S. military amid a steadily growing ecosystem of stealthy aerial threats, especially emanating from China. IRST technologies are also evolving, including with the emergence of systems that can be distributed around an aircraft using smaller individual sensors, which are also sometimes less complex and costly.
The Navy’s particular efforts to field this capability for its Super Hornets, which trace all the way back to 2007, have faced hurdles. The service only formally initiated work on the improved Block II IRST21 in 2018, according to the Government Accountability Office (GAO), a Congressional Watchdog. A Block II prototype pod first flew on a Super Hornet the following year.
Quality control and reliability issues continued to dog the program afterward, as you can read more about here. Following the IOC declaration, a full-rate production decision was expected to come in January 2025, but was delayed.
“The program reported that it would not reach a full-rate production decision by its baseline schedule threshold in January 2025 due to delays incurred during flight testing,” according to a GAO report published in June 2025. “IRST officials told us that operational tests were delayed by 2 months due to software defects that caused IRST pods to falsely report overheating.”
“Director, Operational Test and Evaluation (DOT&E) officials told us that the defect was relatively easy to fix and would likely have been addressed during developmental testing had the program allocated more time for that testing,” the GAO report added. “The program now expects a full-rate decision in June 2025. This is the second time the program breached its baseline schedule in the past 3 years.”
GAO’s June 2025 report also said that DOT&E remained of the view that “the pods were extremely unreliable.”
“These officials said that the program improved pod reliability as it made software updates but only managed to achieve 14 hours mean time between operational mission failures – short of the 40 hours required,” the report said. “As such, DOT&E officials said that deploying the IRST pods without improving their reliability would transfer risk to the Navy’s fleet. Program officials noted that IRST initial capability was achieved without any noted limitations.”
“IRST Block II operational flight test events demonstrated tactically relevant detection ranges against operationally relevant targets and the ability to translate these long-range target detections into stable system tracks to facilitate weapons employment,” DO&TE had said in its own most recent annual report, covering work done during the 2024 Fiscal Year. “The Navy must continue to improve the F/A-18 E/F Super Hornet’s operating software and address existing deficiencies to effectively integrate IRST into aircraft fire control solutions.”
“IRST Block II demonstrated significant reliability problems during operational testing. Throughout the test period, IRST Block II suffered from hardware and software deficiencies, which required the aircrew to restart the pod multiple times,” that report added. “Troubleshooting and repair often exceeded the abilities of Navy maintenance crews and required assistance from Lockheed Martin. Many of these problems were discovered during integrated and operational test after the Navy completed a minimal developmental test program with the representative hardware.”
It is curious to note that there has been no commensurate reporting of reliability or other issues with the IRST21/Legion Pod combination that has been seen flying on Air National Guard F-15s and F-16s for years now. At the same time, whether or not the Air Force has experienced any troubles with those IRST pods is not entirely clear.
To what degree remaining issues on the Navy side have been addressed and/or mitigated is also unclear, and TWZ has reached out the service, as well as Lockheed Martin, for more information.
The decision now to move ahead with full-rate production of the IRST21 is certainly a new vote confidence, especially when it comes to the Navy program.
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