The unique NT-43A RAT55 plays a key role in evaluating air stealth technologies.
The NT-43A RAT55: an essential tool for evaluating air stealth
The NT-43A, nicknamed RAT55, is a unique aircraft designed to measure the radar signatures of other aircraft in flight. Based on a Boeing 737-200, it has been extensively modified to fulfill this specific mission.
Technical modifications to the NT-43A
The RAT55 is equipped with two large radar antennas, located at the front and rear of the aircraft. These antennas measure the radar cross section (RCS) of stealth aircraft in flight. RCS is a measure of an object’s ability to reflect radar waves, expressed in square meters. A low RCS indicates better stealth.
In addition to the radar antennas, the RAT55 has electro-optical and infrared sensors, as well as dorsal fairings that can accommodate other systems. This equipment allows for a comprehensive assessment of the stealth of the aircraft being tested.
A crucial mission for air stealth
The RAT55 is used to validate stealth designs and surface treatments on aircraft. It measures the SER of aircraft from all directions, including from above, which is difficult to achieve from the ground. This capability is essential to ensure that stealth aircraft meet design specifications.
For example, B-2 Spirit bombers undergo maintenance and then fly with the RAT55 to verify that their stealth capabilities have been maintained. The RAT55 is also involved in the development of other advanced stealth programs.
RAT55 operating bases
The RAT55 is primarily based at Tonopah Test Range (TTR) Air Force Base in Nevada, a highly secure facility used for experimental aviation programs. It also operates in test areas in southern California and Nevada, including near Area 51 and Edwards Air Force Base.
These areas offer restricted and secure airspace, ideal for testing sensitive technologies.
A rare appearance in Arkansas
In May 2025, the RAT55 made an unusual flight from the Nevada Test and Training Range (NTTR) to Northwest Arkansas National Airport (XNA), with a stopover in Amarillo, Texas. The reason for this flight remains unknown, but it may have been related to maintenance or modification work.
King Aerospace, a company specializing in military aircraft maintenance and modification, has facilities at XNA Airport. In 2022, the RAT55 had already been observed at another King Aerospace facility in Ardmore, Oklahoma.
The strategic importance of the RAT55
The RAT55 plays a critical role in developing and maintaining the stealth capabilities of the United States. It ensures that stealth aircraft, such as the B-2, F-22, F-35, and future aircraft such as the B-21, meet stealth requirements.
Despite its age, the RAT55 remains a valuable tool for evaluating stealth technologies. However, support for the early 737 models is declining, raising questions about whether it needs to be replaced or supplemented with a new aircraft.
The NT-43A RAT55 is a unique aircraft that is essential for evaluating stealth technologies. Its role in validating stealth designs and surface treatments is crucial to maintaining US technological superiority in military aviation.
War Wings Daily is an independant magazine.