A highly modified Boeing test aircraft long known as “Catfish” has been observed carrying a stealthy underwing infrared sensor pod during a recent landing at Edwards Air Force Base, marking what appears to be a new phase in ongoing systems development for the U.S. Air Force’s F-22 modernization effort.
The aircraft, a unique Boeing 757 Flying Test Bed operated by Boeing and officially registered as N757A, was photographed on Monday by aviation photographer Jerod Harris as it approached Edwards Air Force Base carrying a previously unseen under-fuselage pod. The installation is believed to be an infrared sensing payload associated with what sources describe as a broader “Raptor 2.0” upgrade package for the F-22 Raptor.
The sighting is notable both for the configuration of the payload and for the platform carrying it. The aircraft—known widely by its nickname “Catfish” due to its heavily reshaped forward fuselage—has been a central test asset in the F-22 development ecosystem for decades. However, this may be the first publicly documented instance of it flying with a dedicated underwing store mounted beneath the fuselage in this specific configuration.
The Boeing 757 testbed, originally the first airframe of its type to be built and first flown in 1982, has spent much of its operational life as a flying surrogate for advanced U.S. Air Force sensor and avionics development. Its extreme modification set makes it one of the most distinctive airborne test platforms in the world.
Its most recognizable change is the reshaped nose section, engineered to replicate the radar signature and geometry of the F-22. That modification allows it to house the same AN/APG-77 AESA radar system used in the stealth fighter, enabling realistic airborne testing of radar performance and sensor integration outside of a combat airframe.
In addition to the nose redesign, Catfish features a pair of swept aerodynamic structures above the cockpit. These were designed to facilitate testing of conformal antennas and other elements associated with the F-22’s AN/ALR-94 electronic support measures system. Internally, the aircraft has been extensively reconfigured with racks of mission systems equipment, instrumentation arrays, and a cockpit simulator replicating that of the fighter itself.
These modifications make the aircraft far more than a simple surrogate. It functions as a full systems integration laboratory capable of hosting engineers, real-time telemetry systems, and in-flight evaluation stations, allowing rapid iteration of complex avionics and sensor concepts.
The newly observed under-fuselage pod is believed to be part of ongoing work on an infrared sensing capability linked to the broader “Raptor 2.0” upgrade program. While details remain limited, the system appears consistent with an infrared search and track (IRST)-type sensor designed to complement the F-22’s existing radar and electronic warfare suite.
IRST technology has seen renewed global emphasis in recent years due to its passive detection characteristics. Unlike radar systems, which emit energy to detect targets, IRST systems detect infrared radiation emitted by aircraft and other objects. This makes them difficult to detect and immune to radio frequency jamming, while also providing a passive tracking method that does not reveal the sensor’s own position.
When fused with radar and electronic support measures, IRST data can significantly enhance track quality, particularly against stealth aircraft or low-observable threats. In modern combat systems, this fusion of multiple sensor modalities is central to achieving high-confidence targeting and situational awareness.
The F-22 upgrade program—often referred to informally as “Raptor 2.0”—is expected to incorporate a distributed infrared search and track capability sometimes referred to as an Infrared Defensive System (IRDS). This system is intended to improve all-aspect detection and tracking performance while integrating seamlessly into the aircraft’s existing sensor fusion architecture.
Although the F-22 fleet has already flown with experimental infrared sensor pods installed on operational aircraft, the use of a surrogate platform such as Catfish offers several advantages.
The most significant is operational cost and availability. The F-22 Raptor is among the most expensive and maintenance-intensive tactical aircraft in U.S. service. It is also fuel-limited compared to large test platforms, making extended-duration sensor evaluation missions expensive and logistically complex.
By contrast, the Boeing 757 testbed provides significantly more endurance, cabin space, and payload flexibility. It can accommodate dozens of engineers and technicians onboard, along with full mission systems workstations that allow real-time monitoring and adjustment of test parameters during flight.
This capability is particularly valuable for infrared sensor development, which often requires long-duration flights across varied atmospheric conditions. A large testbed can maintain stable profiles for extended periods while simultaneously hosting instrument operators, analysts, and system engineers in a controlled environment.
Another advantage is geometry. Mounting the pod beneath the forward fuselage provides an unobstructed field of regard, allowing the sensor to collect infrared data across forward, lateral, and downward viewing angles without interference from wing structures or engine exhaust flows.
Historically, smaller surrogate platforms such as the North American Sabreliner have also been used for infrared sensor testing. However, the scale and complexity of modern systems increasingly favor larger, more capable airborne laboratories.
The aircraft’s landing at Edwards Air Force Base is consistent with its long-standing role in U.S. Air Force developmental testing. Edwards serves as the primary hub for experimental flight operations, housing test squadrons, engineering units, and instrumentation ranges that support nearly all major U.S. combat aircraft development programs.
The base has been central to the F-22 program since its earliest phases, and Catfish has been a recurring presence there for decades. Its use in ongoing testing underscores the continued relevance of legacy platforms in modern sensor fusion development, even as new fifth- and sixth-generation systems enter production.
The observed pod also fits within a larger set of upgrades planned for the F-22 fleet. Alongside infrared sensor enhancements, the modernization roadmap includes new stealth-optimized external fuel tanks, improvements to radar processing, upgraded electronic warfare systems, and enhanced data fusion capabilities.
Additional modifications are expected to enable portions of the F-22 fleet to act as airborne control nodes for Collaborative Combat Aircraft (CCA) drones. In this role, the aircraft would serve as a forward command platform, coordinating autonomous or semi-autonomous unmanned systems in contested environments.
This development places the F-22 at the center of evolving U.S. Air Force concepts for distributed air combat, where manned fighters and unmanned systems operate as integrated networks rather than discrete platforms.
The modernization effort also reflects a strategic decision to extend the service life of the F-22 Raptor well into future decades. In 2024, the U.S. Air Force indicated that it no longer maintains a fixed retirement timeline for the aircraft, signaling continued investment in upgrades rather than replacement in the near term.
Beyond the F-22 itself, the Catfish testbed has likely played indirect roles in shaping technologies relevant to the Next Generation Air Dominance (NGAD) initiative. This program is expected to produce the Boeing-developed F-47, a platform that will incorporate advanced sensor fusion, stealth shaping, and manned-unmanned teaming architectures.
Testbeds like Catfish are frequently used as surrogate environments for early integration of technologies that later migrate to operational platforms. As such, sensor and avionics development conducted on the 757 may already be informing design decisions for next-generation systems.
Catfish is not unique in its mission, though it is among the most visually distinctive examples. The U.S. Air Force and industry partners operate several airborne laboratories, including the CATbird, which supports the F-35 program. Internationally, similar concepts exist in both Europe and Asia, where modified airliners and business jets are used to test sensors, radar systems, and mission avionics.
China, for example, operates a testbed based on the Russian-designed Tupolev Tu-204C, which serves a similar role in supporting development of its Chengdu J-20 program.
Despite advances in digital modeling and simulation, physical flight testing remains essential for validating sensor performance in real atmospheric conditions. Infrared propagation, atmospheric attenuation, and thermal clutter are difficult to replicate fully in simulation environments, particularly for systems intended for combat use.
The appearance of a stealth infrared sensor pod on Catfish suggests that the F-22 modernization program is entering a more tangible phase of integration testing for its next-generation sensor suite. While much of the development work remains classified or undisclosed, the use of a large-scale airborne laboratory indicates sustained investment in refining sensor fusion and passive detection capabilities.
At 44 years old, the Boeing 757 testbed continues to serve as a critical bridge between design concepts and operational implementation. However, its long-term future is less certain. As new aircraft programs such as NGAD advance and digital engineering tools improve, the Air Force and Boeing may eventually transition toward newer, purpose-built test platforms optimized for sixth-generation systems.
For now, though, Catfish remains one of the most important—and visually distinctive—assets in the U.S. military’s developmental test fleet, continuing to play a central role in shaping the evolution of the F-22 and potentially informing the technologies that will define its successor.
As Jerod Harris’s photographs show, even after decades in service, the aircraft continues to surface with new and unusual configurations, underscoring its ongoing relevance in some of the most advanced aerospace development work in the world.
