You’ve probably seen pictures of "weird" airplanes online, but nothing quite matches the visual insanity of the NT-43A. It looks like a Boeing 737 that got into a fight with a swarm of bees and lost. Badly.
With two massive, bulbous radomes—one on the nose and one on the tail—it’s easily the most ungainly bird in the sky. To the casual observer, it’s a Frankenstein’s monster of aviation. To the U.S. Air Force, it is a crown jewel. They call it RAT55, or the Radar Airborne Testbed, and it’s basically the only reason American stealth planes can confidently claim they’re "invisible" to enemy eyes.
Honestly, stealth isn't just about the shape of a plane. It’s a constant battle of physics. You can build a B-21 Raider in a clean room, but once it’s in the air, things change. Coatings wear down. Screws loosen. Heat happens. That’s where the NT-43A RAT55 radar test aircraft comes in, acting as a high-tech mirror that tells a pilot exactly how "bright" they look on a radar screen.
Why Ground Tests Just Aren't Enough Anymore
A lot of people think you just put a stealth jet in a big indoor chamber (called an anechoic chamber), bounce some waves off it, and call it a day. That’s great for the design phase, but it doesn't account for the "real world."
When a jet is flying at 30,000 feet, it’s vibrating. The air is pushing against its skin. The engines are pumping out heat. Ground-based systems, like the Dynamic Coherent Measurement System (DYCOMS) in Nevada, are limited by geography and physics. They can only see the plane from certain angles.
The NT-43A changes the game because it’s mobile. It flies in tight formation with its target. If a B-2 Spirit is cruising over Death Valley, RAT55 is right there with it, staring at it from the front, the back, and even slightly above.
By using those massive radar arrays, it collects what’s essentially a 3D "picture" of the target’s radar signature. If there’s a tiny leak—a spot where the stealth coating has degraded or a panel isn't sitting flush—RAT55 finds it.
The Weird History of Serial Number 73-1155
This isn't a new plane. Far from it. This specific airframe started its life as a T-43A "Gator," a navigator trainer delivered to the Air Force back in 1974. Most of its siblings are either in museums or rotting in the boneyard at Davis-Monthan.
But 73-1155 had a different destiny. Around 2000, it was pulled from storage and sent to a facility in Goodyear, Arizona. The transformation was radical. Lockheed Martin’s famous Skunk Works and a secretive company called Denmar were involved in the conversion. They took a humble passenger jet and turned it into an airborne laboratory.
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It’s a bizarre mix of eras. You’ve got a fuselage and engines from the 1960s carrying radar tech that’s probably still classified today. It shouldn't work, but it does.
What’s actually inside those "bulges"?
- Massive Radar Arrays: The front and rear radomes are over 16 feet long. They house powerful radars capable of mimicking the frequencies used by high-end Russian and Chinese air defense systems (like the S-400).
- Infrared Sensors: If you look closely at the top of the radomes, there are small turrets. These are IR sensors that measure the heat signature of the target aircraft. Stealth isn't just about radar; if you’re glowing like a lightbulb in the infrared spectrum, you're still dead.
- Advanced Avionics: The interior is stripped of its trainer seats and filled with data recording stations where engineers analyze the returns in real-time.
The Groom Lake Connection
For years, RAT55 was a ghost. People would see it on flight trackers occasionally, then it would vanish. Its home base was the subject of endless debate. Was it at Tonopah? Edwards?
In 2025, we finally got a clearer picture. Photographers captured the NT-43A performing "touch-and-go" landings at Groom Lake (the infamous Area 51). It was even seen taxiing into Hangar 18, one of the largest and most mysterious buildings on the base.
This confirms its role in "Black Projects." While it spends plenty of time validating the stealth of the B-2 and F-22, its real value is in testing things we haven't seen yet. Think about the B-21 Raider or the Collaborative Combat Aircraft (CCA) drones currently in development. Before those planes go into combat, they have to pass the "RAT test."
Why the NT-43A is Busy in 2026
You might think that after 50 years, the Air Force would want something newer. A 737 Max, maybe? But the "if it ain't broke, don't fix it" rule applies here. Supporting an old 737-200 is getting harder, but the data this specific plane provides is irreplaceable.
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America is currently in a "stealth arms race." Adversaries are getting better at spotting low-observable aircraft using low-frequency radars and multi-static systems. To stay ahead, the U.S. has to constantly tweak its stealth coatings (the "skin" of the plane).
RAT55 is the validator. It’s the "final exam" for any new stealth material. When a B-2 comes out of heavy maintenance, it often goes for a ride with RAT55 to make sure it’s still as invisible as the day it was built.
Spotting the Ghost
If you’re an aviation nerd, spotting RAT55 is the ultimate "win." It usually operates under the callsign RAT55, SABRE98, or STRMY29. It stays mostly within the Nevada Test and Training Range (NTTR), but occasionally it goes on "cross-country" trips.
Just last year, it was spotted in Amarillo, Texas, and parts of Arkansas. Why? Probably for specialized maintenance at contractor facilities like King Aerospace. These rare public appearances are the only times we get to see the weird, bug-eyed plane in high definition.
Next Steps for Aviation Enthusiasts
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If you want to dive deeper into the world of "Black Projects" and the NT-43A, here is what you should do:
- Monitor Flight Tracking Sites: Keep an eye on ADSB-Exchange for the hex code AE0925. This is the unique identifier for 73-1155. It often flies with its transponder off, but it "pops up" occasionally.
- Study the B-21 Raider Program: The B-21 is currently in its flight test phase. Wherever the Raider goes, RAT55 is likely to follow. Look for flight patterns around Edwards Air Force Base.
- Research Low-Observable (LO) Maintenance: Learn about the "RAM" (Radar Absorbent Material) used on stealth jets. Understanding how this material degrades over time explains exactly why a testbed like the NT-43A is a permanent necessity for the Air Force.