Boeing’s 757 Flying Test Bed was recently spotted carrying a stealthy underwing infrared sensor pod under its fuselage. This may be the first time this aircraft, better known as ‘The Catfish’ because of its unique and highly modified nose profile, has ever been seen lugging around a store on this station. The pod itself is part of a larger “Raptor 2.0″ upgrade package being developed for the F-22. Catfish has served as a key systems integration testbed for the Raptor since the 1990s.

Jerod Harris caught Catfish with the pod under its belly as it came in to land at Edwards Air Force Base in California on Monday. Edwards is the main hub for U.S. Air Force test and evaluation activities, and Catfish has been seen there many times over the years as part of its work. The aircraft, which carries the U.S. civil registration code N757A, also happens to be the first 757 ever built, and took to the skies for the first time back in 1982.

As already noted, Catfish has already played a central role in the story of F-22. The aircraft’s heavily modified nose is designed to directly replicate that of the Raptor, and contains the same AN/APG-77 active electronically scanned array (AESA) radar as the fighter. The swept wings on top of the cockpit were also designed to support testing of the conformal antennas for the Raptor’s AN/ALR-94 electronic support measures system and other components of its ‘fused’ sensor suite. The aircraft has supported the development of a wide array of other systems for the F-22, and is packed inside with additional equipment to support those needs in particular, including a replica of the Raptor’s cockpit. You can read more about Catfish and its general history here.

So it is not surprising then that the heavily modified 757 would also be used now to help with continued testing of the new underwing infrared sensor pods for the Raptor. Carrying the pod under the forward end of the fuselage would offer the sensors inside a good open field of view to the front, as well as to the left, right, and down.

The stealthy pods have been test-flown on actual F-22s for years now. At the same time, there are only a limited number of Raptors available, in total, and they are notoriously fuel-hungry, maintenance-intensive, and otherwise expensive to operate. If the particular test plan calls just for level flight, and over extended periods of time, a platform like Catfish could be an attractive alternative. With space for dozens of engineers and technicians in its main cabin, and workstations for them, the aircraft would also offer very different options for testing and evaluating the pod while in-flight. A North American Sabreliner business jet has also been used to test these pods in the past.

N33TR, a Rockwell Sabreliner 65 for Airborne Imaging returns to KJWY/Mid-Way regional Airport as " AIRBORNE33 " carrying one of the future F-22 pods.

It was at Nellis AFB testing the pod alongside RATT55/NT-43A, a radar test bed that regularly flies alongside B-2s. pic.twitter.com/kNADnga7H0

— 𝗦𝗥_𝗣𝗹𝗮𝗻𝗲𝘀𝗽𝗼𝘁𝘁𝗲𝗿 (@SR_Planespotter) July 1, 2024

The capability, in general, for Catfish to carry stores under its fuselage might open up additional possibilities for utilizing the aircraft in support of other testing efforts, if it hasn’t already.

Catfish would also be well suited to supporting testing of other elements of the Raptor 2.0 package. Under the current plan, the Air Force’s F-22s are also set to get a new integrated distributed infrared search and track (IRST) system called the Infrared Defensive System (IRDS).

IRST systems have seen a renaissance across the U.S. military in recent years, as well as elsewhere globally. IRSTs detect and track targets via their infrared emissions, making them particularly valuable for helping spot stealthy targets with features designed to reduce their radar cross-sections. The sensors are also immune to radio frequency electronic warfare jamming and operate passively, meaning they do not emit signals that could alert a target to the fact they are being tracked. IRSTs can also be used to cue or otherwise be linked to other sensors, including AESA radars. This data fusion can provide higher fidelity tracks of multiple targets, as well as improved situational awareness overall.

Increased demand for IRSTs has led to a commensurate increase in demand for testing using multiple platforms. This, in turn, has been a major component of a general uptick in U.S. military flight testing in recent years to support a variety of new, advanced programs.

Other elements of the Raptor 2.0 upgrade plan include new stealthy drop tanks, improvements to the jet’s stealthy features, radar capabilities, electronic warfare suite, and more, as you can read about in detail here.

At least a portion of the Raptor fleet is also set to receive modifications to enable them to act as airborne controllers for Collaborative Combat Aircraft (CCA) drones. The Air Force’s F-22s are set to be the service’s first tactical jets to be used in that role, though others will follow.

The F-22 upgrade work is reflective of current Air Force plans to keep the Raptors in service for decades to come. In 2024, the Air Force said it no longer had a firm retirement schedule for the fighters.

Raptors have been used in recent years as surrogates to support work on the Next Generation Air Dominance (NGAD) initiative, a component of which is Boeing’s F-47 sixth-generation fighter. As such, Catfish will have already been feeding into those developments, which are now firmly a top Air Force priority.

At the same time, Catfish is now 44 years old. Boeing 757s, in general, are increasingly disappearing from service globally as they become more complicated and cost-intensive to sustain. Especially with the work ongoing now on the F-47, it seems likely Boeing will start looking toward a new highly specialized testbed aircraft modified to reflect the particular physical geometry, unique avionics, and other features of the new fighter.

Similarly, the F-35 family also has a dedicated test jet, the Boeing 737-300-based Cooperative Avionics Testbed, nicknamed the CATbird. There are several other airliner and business jet-based testbeds flying globally today, though Catfish is certainly one of the largest and most visually distinctive. Improving digital simulation and modeling tools could allow for less reliance on surrogate testbed aircraft in the future, but they will in no way be eliminated.

China notably has something of a clone of Catfish based on a Russian-made Tupolev Tu-204C airliner, which itself was designed as an analog to the 757. The Chinese jet’s primary purpose has been supporting the development of the J-20 stealth fighter, the country’s closest answer to the F-22.

In the meantime, Boeing Catfish remains a very important part of continued work to improve and expand the capabilities of the F-22. This now extends to testing of specialized underwing pods for the Raptor.

Special thanks again to Jerod Harris for sharing his pictures of Catfish carrying the stealthy sensor pod with us.

Contact the author: joe@twz.com

The post F-22’s ‘Catfish’ 757 Testbed Spotted Carrying Raptor’s New Infrared Sensor Pod appeared first on The War Zone.

NASA is moving to hire a contractor to assess whether or not a Boeing 737-73W can meet its needs for a new reduced-gravity testbed aircraft. The use of planes modified for this role is now new, and they are often called “Vomit Comets” because of the extreme maneuvers they perform to simulate zero-G environments and the physical side effects this often induces. However, there’s an unusual twist here with the specific plane that NASA is now eyeing: it currently belongs to the U.S. Air Force and is part of a “classified military program.” There is a strong possibility that the aircraft in question is a mysterious 737 that the service acquired in 2020, and that has been the subject of much speculation as to its purpose ever since.

NASA’s Armstrong Flight Research Center posted a contracting notice yesterday justifying a planned sole-source contract to Denmar Technical Services, Inc. in relation to “Reduced Gravity Modification” of the 737-73W aircraft. Earlier this year, signs had already emerged that NASA might be in line to get a heavily modified and highly secretive 737 from the Air Force, designated the NT-43A and commonly referred to by the callsign RAT55. However, yesterday’s notice does not appear to refer to the NT-43A, long used as an airborne signature measurement platform and described in the past as the world’s most secretive 737, which is based on a much older 200-series airframe. We will come back to this later on.

What NASA wants now

“NASA requires Denmar Technical Services, Inc. to conduct a feasibility assessment to determine the Boeing 737-73W’s suitability to perform the NASA reduced gravity mission; modify the aircraft cabin, if required, to support reduced gravity operations; perform overdue maintenance and inspections, perform airworthiness restoration tasks, and paint the aircraft exterior with NASA identifiers,” the contracting notice NASA released yesterday explains.

The notice adds that the aircraft, if modified, would be used, at least most immediately, “for the Reduced Gravity Test Bed Project in support of the agency [sic] need for performing validation testing on Space Suits in support of the Artemis program.”

Artemis is NASA’s current effort to return U.S. astronauts to the lunar surface. The Artemis II mission, conducted in April, involved the first fly-by of the Moon by a crewed spacecraft since the end of the Apollo program in the early 1970s. However, the spacecraft did not touch down on the surface. The goal now is for a crewed lunar landing to come in 2028. RAT55 was notably used to support the launch of the Artemis II mission and the subsequent recovery of the capsule after its return to Earth.

Back in January, NASA had put out a separate contracting notice calling for information about new options to provide “parabolic flight services” to simulate “reduced gravity environments, including microgravity” for testing and scientific research purposes. The Florida-based Zero-G corporation is currently the primary provider of these services to NASA, using a retrofitted Boeing 727-200 dubbed ‘G-Force One.’ You can read more about NASA’s general use of Vomit Comets in the context of that notice here.

The Boeing 737-73W under consideration to be turned into a Vomit Comet “is owned by the United States Air Force (USAF). Denmar Technical Services, Inc. has specialized knowledge of this Boeing 737-73W aircraft as they are currently contracted by the USAF to modify the aircraft under a classified military program,” the contracting notice NASA released yesterday adds. “NASA does not have a ‘need to know’ regarding the details of the current modifications being made under the USAF contract and therefore is unable to provide modification details to another contractor or provide another contractor with access to the aircraft. The USAF will transfer ownership of the aircraft to NASA upon completion of the closeout tasks.”

“Denmar Technical Services, Inc. is uniquely positioned to close out work under their existing obligations while performing the feasibility assessment, maintenance, and any modifications required under this action,” the notice continues. “Additionally, due to the constrained timeline for the NASA Extravehicular Activity and Human Surface Mobility Program’s space suit testing for Artemis, NASA requires the assessment and overdue maintenance to be performed immediately upon contract award and any subsequent aircraft modifications to be complete no later than October 1, 2026. The timeline can only be supported if this requirement is fulfilled concurrently with the USAF closeout tasks.”

Denmar is a small aviation firm headquartered in Reno, Nevada. At the time of writing, its website lists a wide array of specialized design, modification, flight testing, and other work among its portfolios. This includes “advanced customized mission system development” that “encompasses the design of unique airborne operator interfaces, specialized emitters and sensors, system integration, and post-mission analytics and processing.” The company also describes itself as the “Nation’s leading experts on IR [infrared] and RF [radiofrequency] survivability, signature modeling, [and] agile software development for analysis and real-world operational assessments.”

In line with all this, Denmar is understood to have been the prime contractor behind the extensive modifications to RAT55. In April, the Air Force confirmed to TWZ that the NT-43A was “being transitioned to start the next phase of its career,” as reflected by its involvement in the Artemis II mission, “after decades of flights supporting the Air Force in various roles.” The aircraft, which is understood to have long called the secretive and remote Tonopah Test Range Airport (TTR) in Nevada home, has been seen much more publicly since then.

Best views of RAT55 yet. Dorsal sensor pod (EO ball) seen in detail here. Also shot inside. I wonder if this is going to be ported in full to a contractor (it is currently operated by a contractor) https://t.co/XoE1zGFN78

— Tyler Rogoway (@Aviation_Intel) April 4, 2026

However, as NASA’s recent contracting notice makes clear, the 737 it is now looking at as a potential Vomit Comet is a much newer 700-series model. TWZ has reached out to the Air Force and NASA for more information.

The curious case of N712JM

As mentioned, it is very possible, if not highly probable, that the 737 NASA is now considering turning into a Vomit Comet is one that the Air Force acquired in 2020, which TWZ explored in-depth at the time. That aircraft, which is a -73W model, is still officially on the U.S. civil register, with the registration code N712JM. Federal Aviation Administration (FAA) records show that the preceding owner of this aircraft was Denmar, which acquired it in 2019. The plane’s history before that is murky, with Boeing delivering it in 2013 to East West Bank via a trusteeship with Wells Fargo Bank, per the FAA’s records.

N712JM had drawn particular attention in 2020 not just because of its transfer to the Air Force, but also because it emerged at that time wearing a green protective coating and otherwise looking like it had just rolled off the production line. It also had some unusual external features that raised questions about its role, as we explored at the time.

In 2020, Jon Ostrower, long-time aviation journalist and editor-in-chief of The Air Current, told TWZ the following:

“This is definitely an airplane that never made it to a formal finish you’d expect from a commercial airplane. The green finish is a protective coating applied to fuselages during manufacturing to protect from scratches and other damage. It is dissolved during painting. You can also still see the manufacturing (line) number as well. That’s from its original trip down the assembly line. There’s also quite a bit of instrumentation visible with sensor wiring leading into the cabin through the passenger windows. This type of arrangement points to a flight test setup of some kind.”

In 2020, N712JM conducted many test flights in U.S. military ranges off the coast of Southern California, flying various flight profiles, some of them quite unusual. The aircraft flew those sorties from Santa Maria Airport in California, and used the callsign STING 38.

The 'mysterious' USAF Boeing 737-700 N712JM is just back to Santa Maria, Ca. after another 3+ hour flight as 'Sting 38'. https://t.co/3sxMyligwM

Seven years old yet still in 'greenie' primer, lots of sensors in odd places… Article: https://t.co/erZf3MMSwi @thewarzonewire pic.twitter.com/ivs2WQFkt4

— Airport Webcams (@AirportWebcams) June 15, 2020

What the Air Force has been using N712JM for to date is unknown. Per FAA, the aircraft has been and continues to be registered to an address at Bolling Air Force Base (technically now part of Joint Base Anacostia-Bolling) in Washington, D.C., which looks to belong to the Air Force’s Rapid Capabilities Office (RCO). The RCO has headed up multiple cutting-edge, high-priority programs over the years, including the development of the B-21 Raider stealth bomber and the X-37B reusable spaceplane. A 737-based platform could be configured to support an array of different research and development and test evaluation activities that would fall under the purview of RCO, as well as other stakeholders that this office might engage with.

There has also been some speculation over the years that N712JM might have transformed into an Air Force 737 with the serial number 21-0024, but this appears to still be unconfirmed. The 21-0024 serial has more recently become associated with other shadowy 737s tied to the U.S. military, which have civilian-style paint schemes and may also be on the U.S. civil register. One of them was notably spotted in 2025 at a U.S. forward operating location in El Salvador, sitting directly alongside an Air Force AC-130J Ghostrider gunship and a U.S. Navy P-8A Poseidon maritime patrol plane. This, in turn, raised questions about its involvement in the ongoing U.S. campaign of strikes on alleged drug smuggling boats in the Caribbean and the Eastern Pacific Ocean, as TWZ previously explored in detail.

21-0024, for reference. When I spotted it, FR24 was indeed calling it N712JM, though ADSBx had the BuNo and a different hex. https://t.co/3WwV3kxBC4

— Volgowrath (@volgowrath) April 27, 2023

Sightings and flight tracking data have also pointed to N712JM being a resident at the Sierra Nevada Corporation’s (SNC) facility at Colorado Springs Airport, in the Colorado city of the same name, over the years. SNC is well known for highly specialized and unique aircraft modification work, especially for the U.S. military, but its exact connection to this 737 is unclear.

Interestingly, there have been several online flight tracking data ‘pings’ suggesting new activity related to N712JM at Colorado Springs Airport since at least February of this year. However, there do not appear to be any confirmed flights by the aircraft from there in that same timeframe. This airport notably sits adjacent to Peterson Space Force Base.

N712JM was on again today, this time thing ping is outside the hangar but that may not be accurate https://t.co/ijkrCDLmUh pic.twitter.com/mCdJbY5OOI

— 𝗦𝗥_𝗣𝗹𝗮𝗻𝗲𝘀𝗽𝗼𝘁𝘁𝗲𝗿 (@SR_Planespotter) April 8, 2026

Are we seeing the revival of N712JM? Last ping about 2 hours ago. What will it look like? https://t.co/vnFH9W6Afw pic.twitter.com/MZSLhkwXv8

— 𝗦𝗥_𝗣𝗹𝗮𝗻𝗲𝘀𝗽𝗼𝘁𝘁𝗲𝗿 (@SR_Planespotter) March 25, 2026

There is still a possibility that NASA could be looking at a different Air Force 737-73W for possible conversion into a Vomit Comet. As the contracting notice makes clear, the aircraft in question is currently in the classified realm. At the same time, this seems far less likely to be the case given everything that is known (and still unknown) about N712JM.

A separate question does exist now as to what effort the Air Force might be in the process of closing out that would allow it to transfer any classified 737 to NASA. TWZ has previously raised tangential questions about how the Air Force might fill the resulting gaps left by the highly-specialized RAT55 moving on to the next stage of its career. It is certainly interesting in its own right that NASA seems to be focused heavily at the moment on leveraging some of the most secretive 737s in existence today to support its much less sensitive needs.

More details may emerge if Denmar deems the “classified” Air Force 737 to be a suitable starting place to create a new Vomit Comet to support NASA’s reduced gravity training needs and the Artemis program.

Update: 3:45 PM EST –

In immediate response to our queries, NASA has directed us to an additional notice about the award of the sole-source contract, valued at $8.4 million, to Denmar Technical Services back on June 1.

“The contractor will modify a Boeing 737-700 aircraft to perform lunar-gravity parabolic flights to test NASA space equipment. Once modifications are complete, NASA Armstrong will own the aircraft and oversee aircraft operations out of NASA Johnson,” the notice says. “The aircraft will be used to validate astronaut lunar suits and associated crew systems required to support Artemis mission objectives. This can be done with the modified 737 aircraft in an operationally relevant, reduced-gravity environment prior to lunar mission execution.”

No mention is made here about the sourcing of the aircraft from the Air Force or its classified mission work, as outlined in the sole-source justification that was released yesterday.

Update: 6/11/2026 –

The U.S. Air Force has provided TWZ with a brief statement about the 737-73W aircraft in question.

“The Boeing 737-73W aircraft was originally procured to serve as a flying testbed,” a spokesperson for the service said. “The program ended and [the] USAF is transitioning the aircraft to NASA.”

Contact the author: joe@twz.com

The post Is This Secretive Air Force 737 About To Become NASA’s Next ‘Vomit Comet’? (Updated) appeared first on The War Zone.