Unusual High-Altitude Spy Plane Appears at Special Operations Exercise

German company Grob only ever made five G 520s and one showed up for drills in Indiana.

byJoseph Trevithick|
MH-47 photo


The U.S. military, including the U.S. Coast Guard, has a long history of operating high-flying surveillance aircraft based on or otherwise derived from powered gliders. Recent pictures show U.S. special operators are at least training with one particularly rare type, the Grob G 520.

On July 12, 2017, Indiana’s North Vernon Municipal Airport posted a series of pictures on its official Facebook page of U.S. Air Force and Army special operations aircraft on their way to an exercise. The photographs showed what appeared to be C-130H Hercules and an MH-47G Chinook, as well as what looked like stock photos of a CV-22B Osprey, an AH-6M Little Bird, and multiple MH-60M Black Hawks. There was also a picture of an odd looking white-and-gray aircraft and someone had blacked out its only apparent marking.

We have been unable to confirm the exact model or owner conclusively. However, this plane is most likely the Grob G 520 EGRETT II, which Bear Defense currently owns. The defense contractor, based in Tampa, Florida, home of U.S. Special Operations Command (SOCOM), refers to the plane as the “NYX ISR” on their website. At the time of writing, the company had not responded to a request to confirm they had participated in any recent U.S. military exercise in Indiana or provide additional information about their aircraft, which carries the registration N520DM and has subdued shark mouth art on the nose. SOCOM had similarly not returned a request for more information on the drill, which was called Total Force Exercise (TFX) 17-3.

From the image on their website, Bear Defense's NYX ISR has a large sensor turret, which almost certainly contains a full-motion video and a forward-looking infrared system. For some reason, this appears to be missing on the aircraft at North Vernon Municipal Airport. It could be that the crew planned to install it once they arrived or had otherwise removed it for servicing. It is also possible that the U.S. military opted for another particular sensor package for the exercise that would be fitted once the aircraft arrived or that is mounted internally, such as a radar system.

The aircraft spotted at North Vernon Municipal Airport in July 2017., North Vernon Municipal Airport

Bear Defense aircraft appears to have a satellite communications antenna on the dorsal spine, which would allow for sharing video footage or other data in near real time with troops on the ground. In 2015, Bear Defense reportedly installed the SCOTTY Communication Platform-Air on the aircraft, allowing for fast, encrypted streaming of the video feed to internet-enabled terminals.  The rear portion of the aircraft's ventral gondola would be perfect for a side-looking airborne radar with synthetic aperture and/or ground moving target indicator modes, or some combination of those capabilities.

The history of the slim-winged aircraft is somewhat nebulous itself. The design reportedly originated from a late Cold War joint U.S.-German requirement for a relatively low-cost, high-altitude surveillance plane. In response, in the 1980s, Germany’s Grob Aircraft, which still builds powered and unpowered gliders, as well as other aircraft, teamed up with E-Systems and Garrett AiResearch, both in the United States. The name EGRETT comes from a combination of the three companies’ names.

Bear Defense's NYX ISR aircraft, a Grob G 520 EGRETT II., Bear Defense

According to the publicly available accounts, the official purpose of the program, which the U.S. Air Force reportedly nicknamed Senior Guardian, was to provide a cheaper alternative to the U-2 Dragon Lady spy plane for both treaty verification and environmental monitoring purposes. In the 1980s, the United States and the Soviet Union were negotiating the terms of what would become the Intermediate-Range Nuclear Forces Treaty (INF) and the Treaty on Conventional Armed Forces in Europe (CFE). INF entered force in 1988, while CFE did not go into effect until 1990. Both required robust verification methods.

However, “although the mission of the Senior Guardian project is publicly portrayed as focused environmental monitoring and treaty verification, a similar cover story was used during the early years of the U-2 program,” defense information website GlobalSecurity.org’s entry on the aircraft notes. Early on in the Dragon Lady’s development, the Air Force and the Central Intelligence Agency claimed the aircraft was focused on “weather reconnaissance,” referring to the aircraft WU-2s to try and hide their true function.

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The involvement of E-Systems could only have fueled conspiracy theories and the belief that the EGRETT’s official job description was a cover for something else. The Greenville, Texas-based electronics company had previously worked on a number of secretive Air Force programs in the 1960s and 1970s, including the NC/AC-123K Black Spot “gunship.” In addition, the word “Senior” is reserved for Headquarters, Air Force projects and is widely associated with spy planes and associated equipment, such as the “Senior Year” U-2 and the “Senior Crown” SR-71 Blackbird.

Grob and the rest of the team ultimately built total of five aircraft in various versions, starting with the prototype D 450 EGRETT, followed two more D 500 EGRETT II aircraft. The contractors then modified the D 500s into the final G 520 configuration before building a third of these pre-production planes. Finally, Grob produced a two-seat G 520T trainer version.

Whatever, the original impetus, the aircraft with its composite airframe did boast impressive performance characteristics. It was able to carry more than 2,000 pounds of sensors and equipment in any of 12 separate, modular bays, five of which lined the bottom of the fuselage. There was enough room there for turreted day- and night-vision cameras, as well as synthetic aperture radars and other gear, similar to what we see on the aircraft at North Vernon Municipal Airport and on Bear Defense's stock picture of their NYX ISR.

A schematic of the payload bays on the latest G 520NG, similar to those in the original G 520., Grob Aircraft

The G 520 could fly this equipment to an altitude of 50,000 feet. This can’t match the service ceiling of the Dragon Lady, but begins to approach that of the RQ-4 Global Hawk drone. The aircraft has a very narrow cord wing with a span of just more than 108 feet – close in overall length to that of a 737 airliner – another feature it shares with the Global Hawk. Depending on the exact load out and flight profile, the plane reportedly could have a range of more than 1,500 miles or loiter over a particular area for up to eight hours.

While it has single turboprop engine and a slender fuselage, it is not clear if the G 520’s design included any features to make it particularly physically stealthy or acoustically quiet, unlike the Vietnam-era Lockheed YO-3A Quiet Star or the late Cold War Schweizer RG-8A Condor. On its website, Grob does say that its latest version, which it calls the G 520NG, has a “reduced footprint, very low probability of intercept.” The composite structure would help reduce the aircraft's radar cross section and all of the known versions of the aircraft have large exhaust mufflers that could reduce both infrared and acoustic signatures.

Though the INF and CFE treaties remain in force, the end of the Cold War seems to have killed the official requirement for the Senior Guardian aircraft. Neither the United States nor the Germans officially adopted the aircraft in any capacity. Germany formally cancelled its portion, known as the Luftgestutztes Abstandsfahiges Primar Aufklarungssystem (LAPAS), translating to airborne, long distance primary reconnaissance system, in 1993. At that time, the German government’s expected nine aircraft order had an estimated price tag of $800 million.

The Grob G 520 EGRETT II N520DM while still flying with Raytheon in 2010., Mark Harkin via Wikimedia

The Air Force may have briefly reconsidered the concept in the 1990s. David Kier, the deputy director of the National Reconnaissance Office from May 1997 to August 2001, described a “minimalist design” he referred to as the “TR-3,” which “he derisively called ‘a Cessna 172 compared to a 747,’” according to official historical monograph Air Force UAVs: The Secret History. The nomenclature TR-3 is itself the subject of wide speculation.

“A likely candidate for a program fitting Kier’s description was a moderately stealthy (all-composite) high altitude German airframe called Egrett that was built in cooperation with a major American electronics firm,” the history's author Dr. Thomas Ehrhard wrote in a separate footnote. Interestingly, Ehrhard says the aircraft was “optionally piloted,” a detail not found in other accounts.

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In the end, the existing prototypes filtered out onto the open market through the original partners. In 1995, Raytheon bought E-Systems, ultimately renaming it as their Intelligence, Information and Services division. The company’s flight test outfit continued flying at least one EGRETT II for some time afterward, providing support to NASA’s Airborne Science Program. According to the Federal Aviation Administration, this aircraft, N520DM, apparently passed to Bear Defense circa 2012.

The D 450 EGRETT aircraft is also still in the U.S. civil registry, listed as N520EG, and property of a company called Gentran Corporation. This Omaha, Nebraska-based “trucking company” has one employee, according to publicly available records. Spotters caught this all-white aircraft in California in 2012 and it does not appear to match the one flying in Indiana earlier in July 2017.

The two-seat Grob G 520T., Grob Aircraft

Grob continues to offer the updated single and two-seat G 520NG variants, though these aircraft do not appear to be in active production. The company brought the demonstrator to the 2014 Farnborough Airshow in the United Kingdom, claiming it could start series production of the type by 2016. The G 520T appeared at the 2015 iteration of the event, but there is still no word about potential sales.

We do not know if the U.S. military is actively considering adopting the plane again. During TFX 17-3, it could have simply provided a cheap surrogate for a high-altitude system such as the U-2, RQ-4, or even a much more rare aircraft such as the RQ-170 Sentinel, as well as more common aircraft such as the unmanned MQ-9 Reaper or MQ-1C Gray Eagle

Grob claims its G 520NG has the “lowest operational cost in class.” Regardless, the G 520 series would be able to offer roughly comparable capabilities for training purposes, but be significantly simpler and cheaper to operate and maintain than either the Dragon Lady or Global Hawk. On top of that, those aircraft are already in high demand for actual missions around the world. 

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In addition, the modular nature of the Grob 520 would make it particularly well suited for cost effective, rapid testing of new sensors or equipment. At the National Defense Industry Association's annual Special Operations Forces Industry Conference in Tampa, Florida in May 2017, U.S. Air Force Colonel Eric Forsyth, head of SOCOM's Program Executive Office-Fixed Wing, said his organization was actively working on color night vision video cameras, as well as looking into the possibility of color three-dimensional imaging technology, improved radars, and other systems.

No matter the reason why, its still impressive to see this essentially experimental plane still in active use after all these years. You can be sure we'll be keeping a look out for more information on this particular exercise and we'll be sure to follow-up if the Grob G 520 makes any more notable appearances. 

Contact the author: joe@thedrive.com