Gulfstream Special-missions Business Continues To Grow

L3Harris is in the process of delivering the first of a new class of special-missions aircraft, based on the Gulfstream G550 airframe. The first EC-37B aircraft made its first flight in fully mission-equipped configuration in early May.

The EC-37B is an electronic attack platform that targets the enemy’s command and control communications network, as well as radars and navigation systems. Currently the role—known as Compass Call—is handled by the Lockheed EC-130H, a variant of the Hercules. The fleet has been in service since 1982 and, following a lengthy career that included active service in all of the major U.S. military actions over four decades, is ready for replacement.

L3Harris is the lead systems integrator in what is known as the Compass Call Rehost team, alongside Gulfstream and BAE Systems. As its name suggests, the program ports the current Compass Call Baseline 3 system from the EC-130H into the G550. Five Gulfstreams are currently receiving this system and should be in service with the 355th Electronic Combat Group at Davis-Monthan AFB in Arizona by year-end.

Following these initial aircraft will be at least five more with the Baseline 4 system. This employs BAE Systems’ Sword-A technology, with software-defined components and an open-systems architecture. This will allow the system to be updated quickly to meet emerging threats without requiring physical adaptation. The Air Force plans to operate at least 10 EC-37Bs but may expand the fleet to 14 to replace the current EC-130Hs on a one-for-one basis.

Choosing the G550 as a platform for the system highlights the growing trend to employ larger business jet types for the special-missions arena that were once performed by modified airliners or military transports. Advances in electronics have shrunk the size of the mission systems considerably, as well as their power requirements.

Similarly, increased automation, the rise of artificial intelligence, and the improvement in datalink communications have greatly reduced the number of human operators required onboard the aircraft. Compared with earlier platforms, the modern business jet also provides improved range performance, and also higher service ceilings, increasing the effective horizon for surveillance systems. Modern business jet cabin environments also make life far more comfortable for the crew.

Gulfstream is not the only manufacturer to benefit from this trend. Bombardier has seen its Challenger 650 and Global Express/6000/6500 employed for a number of electronic missions—notably the Global 6000-based GlobalEye multi-sensor reconnaissance/airborne early warning aircraft for the United Arab Emirates. Dassault’s Falcon family has also been adapted to a number of electronic roles, and the company is currently working on the Archange, a signals intelligence (Sigint) gatherer for the French air force based on the Falcon 8X.

Gulfstream's Legacy

Gulfstream, of course, is no stranger to the special-missions world, and the sector remains an important element of the company’s portfolio. The original turboprop-powered Gulfstream I was the basis of the U.S. Navy’s TC-4C Academe multi-engine trainer, and the jet-powered Gulfstream II, III, and IV have all been modified for a variety of special missions.

Perhaps the most notable are the two Gulfstream IV-SPs converted for Sigint gathering. Known in service as the S 102B Korpen (raven), the Gulfstreams have recently been active along NATO’s border with Ukraine. Large numbers of Gulfstreams have been acquired by governments and air forces for VIP and staff transport duties, those in U.S. service being designated VC-11 (GII), C-20 (GIII/IV), and C-37 (GV/550).

Perhaps the most important development was the creation of the G550-based Conformal Airborne Early Warning (CAEW) variant, which first flew in May 2006. Developed in concert with Israel Aircraft Industries, the CAEW is a radical modification of the aircraft to house the Elta EL/W-2085 radar system. This is a 360-degree AEW suite developed from the EL/W-2075 Phalcon for the Boeing 707.

In the G550 application, the system comprises two large side-looking L-band phased arrays on either side of the fuselage, with S-band arrays in the nose and tail to complete the 360-degree coverage. Huge fairings were created for the side arrays, while the S-band arrays are covered by large bulged radomes. Completing the major airframe modifications is a large bulged fairing at the top of the fin to house satellite communications antennas.

As well as the major aerodynamic modifications the CAEW has numerous changes internally, including revised cabling, three power generators instead of one, and a liquid cooling system. The flight deck retains the Gulfstream PlaneView cockpit with Honeywell Primus Epic avionics. Six operators are accommodated in the rear of the cabin, while the forward cabin houses most of the electronics along the sides, including the transmit/receive modules for the side-facing arrays.

CAEW aircraft entered service with Israel in February 2008, known locally as the Eitam. Singapore acquired four to replace its E-2 Hawkeyes, and subsequently Italy acquired two CAEW machines that have played their part in proividing AEW coverage along the border with Ukraine. They are also  in Italian service as E-550As.

CAEW and Sigint Derivatives

Clearing the much-modified aerodynamics of the CAEW for service has smoothed the path for a number of derivatives that employ the same modifications. The first was the NC-37B, a single aircraft employed by the U.S. Navy’s VX-30 for range support duties over the Pacific missile test range. The EC-37B Compass Call aircraft for the Air Force also employs the CAEW aerodynamic configuration.

Experience with the CAEW led Israel to co-develop another variant, known as the Special Electronic Mission Aircraft, or Shavit in Israeli service. This features an Elta EL/I-3001 Sigint system with a large canoe fairing for housing electronic surveillance antennas. It retains the fin-top Satcom bulge. Collectively the Israeli-modified Gulfstreams are called Nachshon, and the latest derivative to appear is the Oron. This returns to the CAEW configuration but has a multi-sensor suite that performs a range of surveillance roles, including maritime intelligence-gathering and aerial imaging. The EL/W-2085 radar and AEW role are retained.

In 2015, Australia joined the Gulfstream special-missions club, ordering two aircraft to be known as the MC-55A Peregrine in Royal Australian Air Force service. As many as five could be bought of this version, which is equipped with the Airborne Intelligence, Surveillance, Reconnaissance and Electronic Warfare (AISREW) multi-sensor system. Flight trials got underway at Gulfstream’s Savannah, Georgia headquarters in May 2022. The MC-55A features an underbelly canoe fairing but also has a tail bulge and satcom fairing similar to those of the CAEW aircraft.

Italy has also acquired two AISREW-equipped Sigint versions of the G550 to answer its Joint Airborne Multi-sensor Multi-mission System (JAMMS) requirement. They will replace the single Aeritalia G-222VS that was used for many years. The first arrived in Italy in May 2022 but appeared to have not yet received its mission equipment, which is to be integrated by L3Harris and includes the Leonardo Osprey 50 radar.

Additionally, Italy has bought six “green” G550s for modification to special-missions configurations at a later date, which will ultimately raise its number of special-missions Gulfstreams to 10. It has not been made public which configurations that the additional machines will be modified to. It has recently emerged that the Italian air force is looking at two or perhaps three of them being completed as electronic attack platforms, using similar mission equipment to that installed in the EC-37B Compass Call aircraft.