Spain is moving ahead with plans to rebuild its airborne signals intelligence (SIGINT) capability, with the Airbus A321— part of the highly successful A320 twin-engine airliner family— selected as the basis for three new SIGINT aircraft.

The choice is disclosed in the latest issue of Spain’s , the Ministry of Defense’s official publication. Airbus and Indra are currently working on the program’s conceptual design under the Santiago II initiative, which aims to deliver a crewed platform capable of collecting and processing intelligence across the electromagnetic spectrum.

The program is intended to restore a capability Spain lost when its last Boeing 707 SIGINT aircraft was retired in 2014. Equipped with Israeli SIGINT equipment, this 707 was designated TM.17-4 in Spanish service, and nicknamed (Queen of the Spectrum).

También del 707-351C (TM.17-4 / 47-04) "BRUJO".

@EjercitoAire @SpottersMurcia April 17, 2020 It served in the 47th Mixed Air Force Group, alongside four Dassault Falcon 20s (designated TM.11 in Spain), that were used for navigation aid calibration, remote sensing, and electronic warfare training.

The new aircraft will have to undergo extensive modification, including the installation of antennas, receivers, signal-processing equipment, operator consoles, communications systems and associated electrical and cooling infrastructure.

Indra is expected to provide much of the mission-system architecture. The company’s AirSign concept, unveiled in 2023, incorporated COMINT and ELINT sensors alongside data fusion, real-time signal analysis, communications, and command-and-control functions.

While COMINT is concerned primarily with collecting intelligence from communications, ELINT focuses on non-communications electromagnetic emissions, including radar signals. Together, these capabilities provide a much fuller intelligence picture of not only what the enemy is doing in terms of their electronic emissions, but what they are planning, and their processes of operation.

Bizjets have become the platform of choice for many new intelligence aircraft particularly where operators want a relatively low-cost, long-endurance platform with a smaller logistical footprint. Aircraft such as the Bombardier Global 6000/6500 Gulfstream G550 Dassault Falcon 8X have been adapted for electronic intelligence and special-mission roles.

Spain’s decision to use the substantially larger A321 points instead toward the other end of the spectrum, providing significantly more room for antennas, processing hardware and crew, and allowing the aircraft to carry a much larger and more power-hungry mission system than the typical bizjet-based SIGINT platform.

At one time, the A321 was envisaged as the platform for NATO’s Alliance Ground Surveillance (AGS) system, which provides the alliance with reconnaissance capabilities, including synthetic aperture radar. However, this capability was eventually fielded on NATO’s fleet of five RQ-4D Phoenix uncrewed aerial vehicles, specialized versions of the Global Hawk.

Elsewhere in Europe, Airbus launched a risk-assessment study for France’s future maritime patrol aircraft (MPA), also to be based on an A321 platform Billed as a “flying frigate” by the company, the new MPA is intended to replace the French Navy’s Dassault Atlantique 2 fleet and emerges at a time when NATO nations are increasingly adopting the in-production Boeing P-8 Poseidon for their maritime patrol requirements.

Airbus does, however, have relevant experience in the conversion of airliners for military roles. The company’s A330 Multi-Role Tanker Transport (MRTT) aircraft are modified at Airbus’s Getafe facility providing an existing industrial base for converting commercial-derived aircraft into specialized military platforms.

The Santiago II program is currently in its definition phase. Spain awarded Airbus and Indra a €16-million ($17.9-million), 18-month contract to study the platform and define the overall system. A subsequent phase will cover modification and integration of the three aircraft. The Spanish Ministry of Defense estimates the complete program at approximately €436 million ($489 million).

The program also has an industrial objective. Spanish authorities want domestic industry to acquire expertise and control over the integration of the SIGINT system, rather than simply purchasing a finished foreign intelligence aircraft.

The A321-based Santiago II fleet is intended to address the shortfall left by the retirement of the specially modified Boeing 707, providing a substantially more modern platform, and with more airframes for improved availability.

The three new aircraft will also complement Spain’s emerging uncrewed SIGINT capability. The Spanish Air and Space Force is introducing the L3Harris Scalable Open Architecture Reconnaissance (SOAR) system on its Predator B drones, giving the fleet ELINT and COMINT collection capabilities. The two systems are likely to fill different niches: the Predator B offers a relatively persistent, lower-cost uncrewed collection option, while the much larger A321 will provide substantially greater payload capacity, onboard processing, and crewed mission-management capabilities. Together, they will give Spain a layered airborne SIGINT architecture.

Spain’s decision also reflects a broader drive to invest in long-range SIGINT platforms capable of collecting, processing, and fusing vast amounts of electromagnetic data, as competition over the electromagnetic spectrum becomes increasingly central to modern warfare If the program remains on schedule, three heavily modified A321s will eventually provide Spain with a persistent airborne capability to detect, classify, locate, and analyze electromagnetic emitters in support of a host of operations. Especially when paired with the Predator B, the capability will likely be of considerable interest to other NATO partners in Europe, too. The post Spain Picks Airbus A321 For New Electronic Intelligence Aircraft