The USAF's secretive NT-43A testbed is a highly modified 737-200 that goes far beyond ground-based radar and infrared signature testing on stealthy aircraft by plying its trade high up in the sky in their target aircraft's natural operating environment.
The aircraft's massive radomes and structural modification were said to have been designed by Lockheed's Skunk Works and were installed by the Goodyear Aerospace plant in Arizona around the turn of the century.
Before that, USAF serial number 73-1155 lived its life as a humble T-43A navigational training aircraft from 1974 to 1997. It was then retired to the boneyard and stored there for over two years before being chosen for its new unique role. The aircraft's first flight in its monstrous NT-43A form was on March 21, 2001.
According to Globalsecurity.com, the NT-43A's genesis may have deep roots dating back to the origins of stealth technology itself. It seems that the company behind the project has direct links to the creator of the famous Skunk Works' ECHO-1 software program that resulted in the stealthy 'Hopeless Diamond' which eventually turned into the Have Blue demonstrator and then the famous F-117A Nighthawk.
Boeing NT-43A Radar Test Bed aircraft.