Return of IRST: America revives infrared tracking in aircraft
How do you detect an airplane that is too far away to see? Radar is not the only solution—an airplane can be located using an IRST sensor. Although this solution was invented by Americans, modern American aircraft lack it. The Russians, on the other hand, successfully use IRST.
Many modern aircraft have a characteristic detail in the front part of the fuselage—a small dome, usually located slightly below the pilot's cabin. It houses a very important sensor—IRST (Infra-Red Search and Track). What is its role?
IRST (infrared search and track) is an infrared sensor that allows the detection of objects that differ from the background temperature, which to some extent also applies to stealth aircraft. Unlike radar, IRST works entirely passively—it does not reveal the presence and position of the aircraft using it, and the target does not know it is being tracked.
IRST sensor is standard in Russia
The first IRST sensors were used by Americans in their F-101, F-102, and F-106 aircraft at the turn of the 1950s and 1960s. These sensors were far from perfect at the time—they were more of a complement to radar than an independent sensor.
Combined with a radar screen, the IRST signalled the detection of an object, but determining its exact location required activating the radar. Despite this, such sensors were included in subsequent American machines like the F-8 Crusader, F-4 Phantom, and F-14 Tomcat.
With technological advancements in the USA, IRST sensors were abandoned, and pilots' situational awareness relied on increasingly sophisticated radars—aircraft such as the F-15, F-16, F-18, and F-22 do not have infrared sensors in their base versions.
This solution was, however, developed and used in their aircraft by the Russians—the characteristic dome housing the sensor can be seen in machines from the MiG-29 and Su-27 families. IRST has also been included in Dassault Rafale and Eurofighter Typhoon aircraft.
How does IRST work?
Modern infrared search and track systems offer significant capabilities—they allow the detection of an aircraft from distances of tens of kilometres (the detection distance increases when the target uses afterburners). Their role is not limited to air target detection—thermal signatures can also detect and identify sea and ground targets.
The advantages of IRST have once again been appreciated by Americans. An advanced, space-scanning sensor of this type is included in the F-35 (Electro Optical Targeting System - EOTS).
Older aircraft—originally without the sensor—are also being equipped with it through attached pods, significantly increasing passive target detection capabilities.
IRST for American aircraft
Thus, the IRST sensor (IRST21/AN/ASG-34) has been integrated in recent years with the F-16 and F-15, which can use it thanks to the Legion Pod. The infrared search and track sensor is also part of the modernization package for the F/A-18F Super Hornet.
The infrared sensor will also be installed in the F-22 Raptor (reports on this appeared in March 2024). In early 2024, IRST sensor tests were also successfully conducted on the Gripen E aircraft.
