AN/AAS-42

AN/AAS-42. The AN/AAS-42 is an advanced airborne infrared search and track (IRST) system developed for the United States Navy. It is a passive, long-range sensor designed to detect and track airborne targets by their thermal signatures, providing a critical capability for beyond-visual-range engagement. The system was primarily integrated onto the F-14 Tomcat as part of its late-service upgrade packages, enhancing the aircraft's situational awareness and combat effectiveness.

Overview

The primary function of this sensor is to provide a passive detection capability, allowing aircraft to locate and track adversaries without emitting detectable radar signals, thereby maintaining electronic silence. It operates by sensing the infrared energy emitted by targets such as aircraft engines and airframe friction, feeding data into the aircraft's central fire-control system. This technology proved particularly valuable for fleet defense missions, complementing the powerful AN/AWG-9 radar carried by the F-14 Tomcat. Integration with the Joint Tactical Information Distribution System (JTIDS) allowed for secure sharing of targeting information within a battle group.

Development and design

Development was led by Raytheon under contract from the Naval Air Systems Command (NAVAIR) during the late 1980s and early 1990s. The design leveraged advancements in infrared focal plane array technology and high-speed digital signal processing to achieve high sensitivity and track resolution. Key engineering challenges involved stabilizing the sensor pod for precise aiming from a high-speed platform and filtering out background clutter from the sea surface and clouds. The system's design allowed it to be housed in a streamlined pod mounted on the starboard wing glove pylon of the F-14 Tomcat, interfacing directly with the aircraft's MIL-STD-1553 data bus.

Operational history

The system entered fleet service with select F-14D Super Tomcat squadrons in the mid-1990s, including units like VF-2 and VF-31. It saw operational use during patrols enforcing the No-Fly Zone over Iraq following Operation Desert Storm, where its passive tracking capability was used to monitor Iraqi Air Force activity. The sensor provided a significant tactical advantage during exercises like Red Flag and TOP GUN, demonstrating enhanced detection ranges against simulated threats like the MiG-29. However, with the retirement of the F-14 Tomcat from U.S. Navy service in 2006, the operational use of this specific system concluded, though its technological legacy informed later systems like the AN/ASQ-228 ATFLIR.

Variants

The primary variant was the AN/AAS-42 itself, deployed on the F-14D Super Tomcat. A related developmental effort, sometimes referenced, was the AN/AAS-42A, which incorporated software and processing upgrades. Technology from this program directly contributed to the IRST21 system developed for international customers and influenced the sensor suite designed for the F/A-18E/F Super Hornet. The core infrared sensor technology also found applications in other Raytheon products, including systems developed for the Missile Defense Agency.

Specifications

The sensor typically operated in the mid-wave infrared band for optimal atmospheric transmission. It featured a high-resolution staring focal plane array and was housed in an aerodynamic pod approximately 2.5 meters in length. The system provided 360-degree coverage in azimuth via aircraft maneuver and had a precise stabilization system to maintain line-of-sight. It could track multiple targets simultaneously and its output was integrated with the display systems in the F-14 Tomcat cockpit, including the Tactical Information Display.

Category:Aviation electronics Category:United States Navy avionics Category:Infrared systems