The shadowy world of flying sensor test bed aircraft, both foreign and domestic, is a fascinating one. These highly modified airliners and business jets do critical work validating new radars, missile seekers, data-links, targeting pods and much more. Some of the shyest among them also work to quantify aircrafts' thermal and radar signatures from an air-to-air perspective. But one of these aircraft—a gonzo-nosed DC-9, known as a NC-9D, with an interesting backstory—has been suddenly quite active and seems to suffer from a case of multiple identifies.

The DC-9 in question began its life 41 years ago as a typical airliner and went on to serve with Ansett, Spirit, and Midway airlines. Then in 1998 it was converted into a major avionics and sensor systems test bed by BAE and Raytheon. The jet had a major modification to its nose section, with a big bulbous fairing installed that can accept modular sensor payloads, such as fire control radars and missile seekers. The aircraft is also fitted with a large communications array that runs along its spine. A ventral antenna farm is also present on the aircraft as well.

Akradecki/Wikicommons Firebird II

The aircraft was named "Firebird II" and it wore a high-profile purple and white scheme with a big phoenix on its tail. Its civilian registration was N932ML. In the mid 2000s the jet was put into storage at Mojave Air and Space Port before being brought back into service a couple years later in 2008, when it began flying sporadically for testing assignments once again. At some time there appears to have been an organizational change with how the aircraft was owned and operated. According to Flightaware.com, the last time the aircraft was flown under its N number—which it supposedly still wears—was in 2011. According to FAA records the aircraft's registration is not active and hasn't been for some time. What's most interesting is that the owner under its lapsed registration is listed as the US Navy with an address at Naval Air Weapons Station China Lake—the Navy's leading-edge research and flight test center near Death Valley, California. The jet, which has been repainted in a discreet blue and white motif, sans giant phoenix on its tail, also has the active Navy bureau number 168277, which odd. But what makes all this even more interesting is that it has been flying under a completely different N number, that being N879AD. This registration does not exist at all in the FAA's database.

James O'Rear N932ML rotating away from Tucson International Airport after leaving the Raytheon Missile Systems compound.

The aircraft shows up on Flightaware.com and on ADS-B flight trackers under this registration and it has been quite active over the last month and a half, flying between Tucson, Phoenix, Mojave, Holloman AFB, and NAS Point Mugu. The fact that it has been flying under this registration for at least four months largely discounts the possibility that it's the result of some sort of error.

Flightradar 24 Just some of the tracks the NC-9D has been making as of late (NAS Point Mugu 2X and Holloman AFB). As of yesterday it was still flying missions out of NAS Point Mugu.

Convoluting things even more is that the aircraft also flies under the callsign "Flight Systems 01" which is a BAE Systems reference to their aerospace modifications and services division based at Mojave Air and Space Port. In the following air traffic control audio you can actually hear the aircraft as "Flight Systems 01" on approach to Tucson International and being cleared to taxi to Raytheon's hangar.

Flightaware.com Recent flight log of the NC-9D under the non-existent N number N879AD. Starting November 14th there is a big uptick on flights operations.

So what's going on here? We really can't say conclusively. Even the arrangement of who owns, operates, and provides testing systems for the aircraft remains unclear. It very well could be a convoluted arrangement where the Navy owns the jet but it is operated and modified by BAE Flight Systems, while Raytheon and BAE Systems provide sensors and systems for testing purposes. These types of complex and often fluid arrangements between the DoD and defense contractors aren't unheard of by any means when it comes to sensitive missions and projects, and they can be just as much a tool used to hide an aircraft's true identity as one of operational convenience. But this still doesn't explain why the aircraft is flying under a non-existent registration or why the registration number it wears isn't even active or in most cases relevant if it is indeed a military aircraft.

James O'Rear The NC-9D's nose section can accommodate different fairings to test different radars and missile seeker arrays.