US Air Force deploys secret RATT55 radar test aircraft to strengthen America’s stealth operations
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A rare public sighting has confirmed the operations of the U.S. Air Force’s NT-43A RATT55, a heavily modified Boeing 737-200 radar testbed, at the Groom Lake facility within Area 51. On August 13, 2025, aviation photographer Michał Rokita filmed the aircraft from Tikaboo Peak, the nearest public vantage point, capturing its early morning departure, subsequent circuits, and daylight return.Follow Army Recognition on Google News at this link
Radar test aircraft such as RATT 55 are employed to collect electromagnetic signature data in real flight conditions to ensure that stealth aircraft, new coatings, or repaired structures perform within expected parameters. (Picture source: Youtube/Michał “n01_b4_flash” Rokita and X/Jason Zicker)
The jet performed multiple touch-and-go maneuvers on Runway 32 before making a full landing and taxiing into Hangar 18, one of the base’s largest structures. The sortie revealed the use of the callsign SABRE98 when communicating with Groom Lake controllers while its transponder transmitted RATT55, confirming its identity and linking it directly to Hangar 18, a building already associated with speculation because of its capacity to house any U.S. aircraft and its name’s connection to long-standing conspiracy theories.
Radar test aircraft, such as RATT55, are employed to collect electromagnetic signature data in real flight conditions, offering capabilities that ground facilities cannot reproduce with full fidelity. These airborne laboratories measure radar and infrared returns from every aspect, including head-on, rear, and overhead views, across variable altitudes and environmental conditions. The purpose of such aircraft is to ensure that stealth platforms, new coatings, or repaired structures perform within expected parameters, supporting route planning, survivability models, and maintenance verification. By operating close to their subjects, radar test aircraft allow engineers to validate low-observable technologies under dynamic circumstances, feeding directly into mission planning and equipment certification. Ground ranges such as Groom Lake’s radar cross-section field and natural environments like Death Valley complement this mission but cannot fully replicate the continuous coverage achieved by a dedicated airborne platform.
Examples of radar test aircraft exist worldwide, ranging from modified commercial airliners to bespoke conversions. Airbus adapted an A320 by fitting it with a Eurofighter nose and AESA radar to conduct fighter avionics testing, Lockheed Martin developed the CATBird from a Boeing 737-330 equipped with F-35 avionics and cockpit sections, and South Korea modified a Boeing 737-500 as a flying test bed for the KF-21 program’s radar. Historically, the U.S. used a Douglas TA-3B Skywarrior fitted with AIRSAR and later a Raytheon NTA-3B for stealth evaluation, but these platforms have been surpassed by more advanced testbeds. Among these, the most secretive and still operational aircraft is the U.S. Air Force’s NT-43A RATT55, which remains unique in its configuration and role.
RATT55 originated as one of nineteen Boeing T-43A “Gator” navigation trainers ordered in 1971 and delivered between 1973 and 1974. These T-43As featured equipment such as search and weather radar, TACAN, VOR, LORAN-C, an inertial navigation system, radar altimeter, and full communications suites, and could accommodate twelve navigator students and six instructors. The aircraft fleet served for decades in navigator and combat systems officer training at Mather and Randolph Air Force Bases, with additional airframes used by the Colorado Air National Guard. By 2010 the fleet was retired from service, with some converted into CT-43A executive transports, while one airframe, serial 73-1155, was retained for conversion into a dedicated radar testbed. This airframe became the sole NT-43A, redesignated from a standard T-43 and transferred to Air Force Materiel Command for signature-measurement duties.
The conversion process began after the aircraft was placed in storage at AMARC in 1997, withdrawn in 1999, and delivered to Hill Air Force Base’s Ogden Air Logistics Center for refurbishment. It was then moved to Goodyear, Arizona, in 2000, where Denmar, Inc., working with Lockheed’s Skunk Works, installed its oversized radomes and associated mounts made of carbon-epoxy honeycomb composite. The radomes measure more than 16 feet in length and over 6 feet in diameter, housing fore and aft radar arrays with infrared sensor turrets placed above each. A dorsal enclosure can also be fitted for additional systems. The aircraft rolled out on February 22, 2001, and flew in its new configuration the following month, with EG&G providing flight operations alongside the Janet fleet that services the Nellis ranges. Since then, the aircraft’s unique shape has made it instantly recognizable to observers, even when sighted from long distances under restricted airspace.
RATT55’s mission is to measure and record radar and infrared data from stealth aircraft operating nearby. It has repeatedly been documented flying in formation with B-2 Spirit bombers over Death Valley, a practice consistent with validating radar signatures after depot maintenance or upgrades to radar-absorbent coatings. The aircraft’s role extends to new programs such as the Northrop Grumman B-21 Raider and the Boeing F-47, as well as advanced drone projects, where it provides in-flight verification that low-observable goals are met. Reports have noted the installation of new radomes on its fuselage compared to earlier imagery, pointing to recent upgrades that extend its utility despite the challenges of supporting an aging 737-200 platform. Official statements about its role are scarce, but observations confirm its continued integration into stealth validation activities.
RATT55’s mission is to measure and record radar and infrared data from stealth aircraft operating nearby. It has repeatedly been documented flying in formation with B-2 Spirit bombers over Death Valley. (Picture source: X/Jason Zicker)
Sightings also link RATT55 with broader test operations around Groom Lake and Tonopah. During 2025, while Tonopah Test Range underwent runway works, F-117A Nighthawks were observed flying from Groom, with Rokita and others documenting their sorties. The F-117s, officially retired in 2008 but still used for dissimilar combat training and system trials, are likely supporting Next Generation Air Dominance development by serving as aggressors or as surrogate platforms. Their presence, combined with RATT55’s in-flight measurement capability, illustrates how mature stealth aircraft and airborne laboratories can together provide realistic test environments without exposing new prototypes to public scrutiny. In this way, Groom Lake hosts a combination of legacy stealth assets and dedicated radar test aircraft that continue to contribute to U.S. development programs.
Although the NT-43A primarily operates in restricted Nevada and California ranges, it occasionally makes appearances elsewhere, attracting attention from enthusiasts. In May 2025 it flew across the country, stopping in Arkansas and Texas under the callsign Stormy 29, with a fuel stop at Amarillo. Observers speculated about connections to King Aerospace, which has facilities in Arkansas and had previously hosted the aircraft at Ardmore, Oklahoma. Such trips are rare, and most data about RATT55’s flights come from position-only tracking records or long-distance photography. Despite its age, the aircraft has continued to receive modifications, indicating that it remains in demand for ongoing stealth programs. High-quality images are uncommon because the aircraft seldom leaves the Nevada Test and Training Range, and official comments on its operations remain virtually non-existent.
Attention has also turned to a potential successor. A Boeing 737-700 registered N712JM, briefly owned by Denmar and now tied to the Air Force Rapid Capabilities Office, has flown test profiles off California while still in its factory-green coating. This aircraft has been associated with Sierra Nevada Corporation’s Colorado modification facilities, leading to speculation that it is being developed as a next-generation airborne signature test platform. Observers point to similarities with Denmar’s role in the original NT-43A conversion and suggest that the new jet may eventually replace or supplement RATT55. Until such a replacement enters service, however, the current NT-43A remains the sole aircraft of its kind, continuing to provide in-flight radar signature measurements that are critical for validating and sustaining U.S. stealth technology across bombers, fighters, and drones.
The RATT55 is derived from the Boeing T‑43A “Gator,” a variant of the civilian 737‑200, and likely retains most of the original airframe’s physical characteristics and performance envelope with some expected degradation due to added sensors and radomes. The T‑43A had a length of approximately 100 feet (30 m), a wingspan of about 93 feet (28 m), a height of roughly 37 feet (11 m), and a wing area near 980 square feet (91 m²); it is powered by two Pratt & Whitney JT8D‑9A turbofan engines delivering around 14,500 lbf (64 kN) of thrust each. The empty weight was listed at about 60,210 lb (27,300 kg) with a maximum takeoff weight near 115,000 lb (52,000 kg). Performance records indicate a maximum speed of approximately 586 mph (509 kn, 943 km/h) at 23,500 ft, a cruise speed around 500 kn (580 mph, 930 km/h), a never-exceed speed of roughly 545 kn (627 mph, 1,010 km/h), a range near 2,600 nmi (3,000 mi, 4,800 km), endurance around six hours, and a climb rate of about 3,760 ft/min (19 m/s).
In its RATT55 configuration, the aircraft carries large forward and aft composite radomes—each more than 6 ft (approximately 2 m) in diameter and around 9 to 16 feet long—housing radar arrays and infrared sensor turrets, with an optional dorsal fairing for additional systems. These modifications likely increase aerodynamic drag and weight significantly, reducing cruise efficiency, and potentially lowering both range and operational ceiling compared to the standard trainer version. The installed radar systems have been observed measuring radar cross-sections of B‑2 Spirit bombers and are presumed to support testing of advanced stealth platforms like the B‑21 Raider and Boeing F‑47, though specific radar capabilities and onboard avionics remain undisclosed. While the NT-43A RATT55 shares much of the T-43A’s baseline performance, its role as an airborne radar test platform with specialized sensor pods and radomes suggests somewhat reduced aerodynamic performance and extended mission capabilities tailored to electromagnetic signature measurement.
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A rare public sighting has confirmed the operations of the U.S. Air Force’s NT-43A RATT55, a heavily modified Boeing 737-200 radar testbed, at the Groom Lake facility within Area 51. On August 13, 2025, aviation photographer Michał Rokita filmed the aircraft from Tikaboo Peak, the nearest public vantage point, capturing its early morning departure, subsequent circuits, and daylight return.
Follow Army Recognition on Google News at this link
Radar test aircraft such as RATT 55 are employed to collect electromagnetic signature data in real flight conditions to ensure that stealth aircraft, new coatings, or repaired structures perform within expected parameters. (Picture source: Youtube/Michał “n01_b4_flash” Rokita and X/Jason Zicker)
The jet performed multiple touch-and-go maneuvers on Runway 32 before making a full landing and taxiing into Hangar 18, one of the base’s largest structures. The sortie revealed the use of the callsign SABRE98 when communicating with Groom Lake controllers while its transponder transmitted RATT55, confirming its identity and linking it directly to Hangar 18, a building already associated with speculation because of its capacity to house any U.S. aircraft and its name’s connection to long-standing conspiracy theories.
Radar test aircraft, such as RATT55, are employed to collect electromagnetic signature data in real flight conditions, offering capabilities that ground facilities cannot reproduce with full fidelity. These airborne laboratories measure radar and infrared returns from every aspect, including head-on, rear, and overhead views, across variable altitudes and environmental conditions. The purpose of such aircraft is to ensure that stealth platforms, new coatings, or repaired structures perform within expected parameters, supporting route planning, survivability models, and maintenance verification. By operating close to their subjects, radar test aircraft allow engineers to validate low-observable technologies under dynamic circumstances, feeding directly into mission planning and equipment certification. Ground ranges such as Groom Lake’s radar cross-section field and natural environments like Death Valley complement this mission but cannot fully replicate the continuous coverage achieved by a dedicated airborne platform.
Examples of radar test aircraft exist worldwide, ranging from modified commercial airliners to bespoke conversions. Airbus adapted an A320 by fitting it with a Eurofighter nose and AESA radar to conduct fighter avionics testing, Lockheed Martin developed the CATBird from a Boeing 737-330 equipped with F-35 avionics and cockpit sections, and South Korea modified a Boeing 737-500 as a flying test bed for the KF-21 program’s radar. Historically, the U.S. used a Douglas TA-3B Skywarrior fitted with AIRSAR and later a Raytheon NTA-3B for stealth evaluation, but these platforms have been surpassed by more advanced testbeds. Among these, the most secretive and still operational aircraft is the U.S. Air Force’s NT-43A RATT55, which remains unique in its configuration and role.
RATT55 originated as one of nineteen Boeing T-43A “Gator” navigation trainers ordered in 1971 and delivered between 1973 and 1974. These T-43As featured equipment such as search and weather radar, TACAN, VOR, LORAN-C, an inertial navigation system, radar altimeter, and full communications suites, and could accommodate twelve navigator students and six instructors. The aircraft fleet served for decades in navigator and combat systems officer training at Mather and Randolph Air Force Bases, with additional airframes used by the Colorado Air National Guard. By 2010 the fleet was retired from service, with some converted into CT-43A executive transports, while one airframe, serial 73-1155, was retained for conversion into a dedicated radar testbed. This airframe became the sole NT-43A, redesignated from a standard T-43 and transferred to Air Force Materiel Command for signature-measurement duties.
The conversion process began after the aircraft was placed in storage at AMARC in 1997, withdrawn in 1999, and delivered to Hill Air Force Base’s Ogden Air Logistics Center for refurbishment. It was then moved to Goodyear, Arizona, in 2000, where Denmar, Inc., working with Lockheed’s Skunk Works, installed its oversized radomes and associated mounts made of carbon-epoxy honeycomb composite. The radomes measure more than 16 feet in length and over 6 feet in diameter, housing fore and aft radar arrays with infrared sensor turrets placed above each. A dorsal enclosure can also be fitted for additional systems. The aircraft rolled out on February 22, 2001, and flew in its new configuration the following month, with EG&G providing flight operations alongside the Janet fleet that services the Nellis ranges. Since then, the aircraft’s unique shape has made it instantly recognizable to observers, even when sighted from long distances under restricted airspace.
RATT55’s mission is to measure and record radar and infrared data from stealth aircraft operating nearby. It has repeatedly been documented flying in formation with B-2 Spirit bombers over Death Valley, a practice consistent with validating radar signatures after depot maintenance or upgrades to radar-absorbent coatings. The aircraft’s role extends to new programs such as the Northrop Grumman B-21 Raider and the Boeing F-47, as well as advanced drone projects, where it provides in-flight verification that low-observable goals are met. Reports have noted the installation of new radomes on its fuselage compared to earlier imagery, pointing to recent upgrades that extend its utility despite the challenges of supporting an aging 737-200 platform. Official statements about its role are scarce, but observations confirm its continued integration into stealth validation activities.
RATT55’s mission is to measure and record radar and infrared data from stealth aircraft operating nearby. It has repeatedly been documented flying in formation with B-2 Spirit bombers over Death Valley. (Picture source: X/Jason Zicker)
Sightings also link RATT55 with broader test operations around Groom Lake and Tonopah. During 2025, while Tonopah Test Range underwent runway works, F-117A Nighthawks were observed flying from Groom, with Rokita and others documenting their sorties. The F-117s, officially retired in 2008 but still used for dissimilar combat training and system trials, are likely supporting Next Generation Air Dominance development by serving as aggressors or as surrogate platforms. Their presence, combined with RATT55’s in-flight measurement capability, illustrates how mature stealth aircraft and airborne laboratories can together provide realistic test environments without exposing new prototypes to public scrutiny. In this way, Groom Lake hosts a combination of legacy stealth assets and dedicated radar test aircraft that continue to contribute to U.S. development programs.
Although the NT-43A primarily operates in restricted Nevada and California ranges, it occasionally makes appearances elsewhere, attracting attention from enthusiasts. In May 2025 it flew across the country, stopping in Arkansas and Texas under the callsign Stormy 29, with a fuel stop at Amarillo. Observers speculated about connections to King Aerospace, which has facilities in Arkansas and had previously hosted the aircraft at Ardmore, Oklahoma. Such trips are rare, and most data about RATT55’s flights come from position-only tracking records or long-distance photography. Despite its age, the aircraft has continued to receive modifications, indicating that it remains in demand for ongoing stealth programs. High-quality images are uncommon because the aircraft seldom leaves the Nevada Test and Training Range, and official comments on its operations remain virtually non-existent.
Attention has also turned to a potential successor. A Boeing 737-700 registered N712JM, briefly owned by Denmar and now tied to the Air Force Rapid Capabilities Office, has flown test profiles off California while still in its factory-green coating. This aircraft has been associated with Sierra Nevada Corporation’s Colorado modification facilities, leading to speculation that it is being developed as a next-generation airborne signature test platform. Observers point to similarities with Denmar’s role in the original NT-43A conversion and suggest that the new jet may eventually replace or supplement RATT55. Until such a replacement enters service, however, the current NT-43A remains the sole aircraft of its kind, continuing to provide in-flight radar signature measurements that are critical for validating and sustaining U.S. stealth technology across bombers, fighters, and drones.
The RATT55 is derived from the Boeing T‑43A “Gator,” a variant of the civilian 737‑200, and likely retains most of the original airframe’s physical characteristics and performance envelope with some expected degradation due to added sensors and radomes. The T‑43A had a length of approximately 100 feet (30 m), a wingspan of about 93 feet (28 m), a height of roughly 37 feet (11 m), and a wing area near 980 square feet (91 m²); it is powered by two Pratt & Whitney JT8D‑9A turbofan engines delivering around 14,500 lbf (64 kN) of thrust each. The empty weight was listed at about 60,210 lb (27,300 kg) with a maximum takeoff weight near 115,000 lb (52,000 kg). Performance records indicate a maximum speed of approximately 586 mph (509 kn, 943 km/h) at 23,500 ft, a cruise speed around 500 kn (580 mph, 930 km/h), a never-exceed speed of roughly 545 kn (627 mph, 1,010 km/h), a range near 2,600 nmi (3,000 mi, 4,800 km), endurance around six hours, and a climb rate of about 3,760 ft/min (19 m/s).
In its RATT55 configuration, the aircraft carries large forward and aft composite radomes—each more than 6 ft (approximately 2 m) in diameter and around 9 to 16 feet long—housing radar arrays and infrared sensor turrets, with an optional dorsal fairing for additional systems. These modifications likely increase aerodynamic drag and weight significantly, reducing cruise efficiency, and potentially lowering both range and operational ceiling compared to the standard trainer version. The installed radar systems have been observed measuring radar cross-sections of B‑2 Spirit bombers and are presumed to support testing of advanced stealth platforms like the B‑21 Raider and Boeing F‑47, though specific radar capabilities and onboard avionics remain undisclosed. While the NT-43A RATT55 shares much of the T-43A’s baseline performance, its role as an airborne radar test platform with specialized sensor pods and radomes suggests somewhat reduced aerodynamic performance and extended mission capabilities tailored to electromagnetic signature measurement.
