IRSTs have been around for many decades, and back in the 1960s, many U.S. fighters and interceptors featured them. But in the last four decades or so, the U.S. has fallen far behind when it comes to fielding a modern iteration of the concept and integrating it as part of the Pentagon's air combat doctrine. Russian aircraft have sported the technology consistently through the latter half of the Cold War, albeit with questionable utility , and have not stopped since. Beyond Russian fighters, allied jets like the pan-European Typhoon and French Rafale carry highly advanced IRSTs today. In fact, even recent export variants of the Strike Eagle are equipped with an IRST.

IRSTs have been a major interest of mine for years. You can and really need to read this in-depth feature I did explaining how they work and why they matter and this recent follow-up for full context, but suffice it to say they fill a major and increasingly pressing sensor gap that exists across much of America's tactical aircraft force.

I was recently involved in a project that tasked me with deeply contemplating the technology that could be brought to bear when it comes to learning more about unidentified flying objects, regardless of their origin. During this process, it hit me that just as the proliferation of new fighter-borne active electronically scanned array (AESA) radars was key in detecting mysterious objects with low radar cross-sections that were flying in the vicinity of U.S. Navy fighter aircraft, a reality that The War Zone was first to report on in detail , the looming Pentagon initiative to field very capable infrared search and track systems (IRSTs) could have even a larger impact. It could even serve as the final technological element needed to springboard potentially revolutionary data collection on the phenomenon. As it sits now, not only is the Navy's Super Hornet fleet slated to get IRSTs very soon, but the Air Force's fighter aircraft tasked with protecting the homeland, and the F-15C, in particular, are also set to get these sensors.

This American UFO renaissance of sorts was further catalyzed by a number of bizarre incidents involving U.S. Navy fighter pilots and puzzling objects operating within tightly controlled and highly monitored airspace . Regardless of what these things actually were, and in some cases, there are compelling explanations pointing to the possibility that they may be very much of terrestrial origin , we know that a relatively recent revolution in fire control radar technology was a major factor in detecting them. But there is about to be an even more relevant leap in U.S. fighter aircraft sensor capabilities that could prove far more significant when it comes to more easily detecting and classifying these strange objects, and thus explaining, or at least better defining some aspects of the phenomenon.

America's long and murky relationship with unidentified flying objects has taken an abrupt turn in recent years and especially in recent months as the Navy has officially admitted that its pilots are encountering things it cannot, or isn't willing to explain, at an alarming rate . With this news, the establishment of high profile UFO-related groups like To The Stars Academy , as well as a new level of engagement by the press in regards to the topic, the public's fascination with the phenomena has once again been elevated.

Although the performance of these systems was sorely lacking for many decades, the fact of the matter is that the IRST's time has finally come. These sensors are far more sensitive than their predecessors and aided by fast computer processing and highly specialized software, as well as integration with the aircraft's other sensors and mission computer, they are exponentially more capable than they were in the not so distant past.

USAF A 1960s vintage F-101 Voodoo equipped with an IRST.

While radars use the radio frequency spectrum to detect and track targets, something that can be challenging to do when said target has a low radar cross-section due to is size, shape, and/or coatings—in other words, it's stealthy—or due to the presence of electronic warfare tactics that can jam, confuse, and spoof radars, IRSTs have no such limitations. They mainly work in the long-wavelength infrared band and are passive in nature. In other words, unlike radar, they emit no energy at all. Instead, they rapidly peer around the sky looking for targets that radiate or reflect infrared energy. The IRST's main limitation isn't really tied to enemy tactics at all, it's atmospheric conditions that can adversely affect its detection ranges. While IRSTs are increasingly important when it comes to countering stealthy fighters, and especially those that will increasingly operate in combat environments where electronic warfare tactics are being employed, those same attributes make them ideal for detecting, tracking, and further investigating the puzzling objects Navy pilots report encountering. In those cases, the craft are hard to continuously track on radar and in some cases, active jamming seemed to be employed against the pursuing fighter's radars. In either case, the IRST would have remained totally unaffected. Beyond being able to detect targets when radar cannot, or at least when it can't consistently, the IRST's benefits are synergistic as it can work in tandem with the jet's radar and targeting pod to detect, track, and gain telemetry and visual information on the target in question. For instance, the IRST can be cued to the targets the fighter's radar detects, and it can do this over significant ranges. This means that even if the radar loses lock intermittently, it can more easily regain it as the IRST will continue to track the object. In addition, because of the IRST, a lock of some type is never actually lost. As a result, far more resilient tracking can be realized against stealthy targets or those that are employing electronic warfare tactics. Conversely, if the target has a faint infrared signature, but radar can detect it, the IRST can regain tracking the target more easily with the help of the radar or it can begin tracking it once it has come close enough to the IRST sensor to be detected. Beyond that, IRSTs allow fighter pilots to hunt and even engage aerial opponents 'silently,' as in without turning on their radar at all. The radar's emissions can give away not only the presence of the fighter it is attached to, but also its location. So, the IRST can act independently of radar entirely and be used as a primary, standalone air-to-air sensor system.

Boevaya Mashina/Wikicommons Su-27's IRST mounted in front of the windscreen. The USSR has been steadfast adopters of IRST technology just as the U.S. moved away from it during the middle part of the Cold War. Up until the last two decades, these systems had somewhat limited utility.

Also, remember that radar and IRST are just two of the fighter's three primary sensors. The third one is the targeting pod, which leverages infrared sensors, as well, but does so in a very different manner than the IRST. There is actually a fourth primary sensor group, that being electronic support measures (ESM)/radar homing and warning receiver (RHWR), but as far as we know, these mysterious objects don't emit RF energy that can be detected by these systems. Traditionally, targeting pods are used for laser-designating ground targets and for non-traditional reconnaissance, but they are also used for enhanced-range visual detection and tracking of aerial targets. This was a secondary function for many years of various targeting pods, but more recently it has become a primary one. While Super Hornets carry the Advanced Targeting Forward Looking Infrared (ATFLIR) targeting pods primarily for ground attack and surveillance, the USAF's F-15Cs have adopted the more capable Sniper targeting pod specifically for long-range high-definition identification of airborne threats. This is very useful for Air National Guard F-15 units that sit alert, patrol America's vast maritime borders, and protect the country's coastal population centers from airborne attack.

Sgt Pete Mobbs/MOD The EF-2000 is equipped with the PIRATE IRST, an advanced system that is integrated into the Typhoon's combat systems architecture.