The U.S. Army has completed the divestment of its three aerial intelligence, surveillance and reconnaissance (A-ISR) aircraft types, marking the end of a five-decade legacy. The RC-12X Guardrail, MC-12S EMARSS-M (Enhanced Medium Altitude Reconnaissance and Surveillance System-Multiple Intelligence), and EO-5C ARL-M (Airborne Reconnaissance Low-Multifunction) have all been retired, the service announced on December 11, 2025.
In July, the ARL-M and Guardrail conducted their last flight missions in Korea, concluding 54 years of A-ISR turboprop support on the peninsula. In September, the last EMARSS-M aircraft conducted its final mission, bringing the fleet’s historical journey to an end.
Five Decades of Service
Beginning in 1971, the Army deployed the first Guardrail aircraft to the 1st Military Intelligence Battalion in Germany to monitor Soviet Bloc troop movements in East Germany and Czechoslovakia. This mission continued for nearly three decades during the Cold War.
Following the Cold War, three Guardrail system configurations deployed with the 224th MI Battalion and 15th MI Battalion during Operation Desert Shield/Desert Storm. The platforms played a crucial role in identifying Iraqi Republican Guard locations and monitoring troop movements for coalition forces, directly supporting the Marine Corps’ advance along the coast into Kuwait City.
Guardrail aircraft from the 3rd MI Battalion maintained continuous operations in Korea since the mid-1970s, monitoring the demilitarized zone. In 1996, ARL-M joined Guardrail in response to a U.S. Forces Korea and U.S. Pacific Command requirement to replace the retiring OV-1D Mohawk aircraft.
The ARL-M provided a crucial moving target indicator/synthetic aperture radar (MTI/SAR) subsystem for the first time, delivering surveillance, imagery reconnaissance, target identification, and communications intercept capabilities that significantly exceeded the aging OV-1D Mohawk’s performance.
The EMARSS became the final aircraft to join the Army’s A-ISR turboprop fleet. Based on the Beechcraft King Air 350ER platform, the first prototype flew in 2013 and became operational by 2016, with deployments to Africa, Latin America, Iraq, and Afghanistan. The program used common architecture with five different variants, allowing the aircraft to respond to diverse operational demands while remaining at the technological edge of ISR collection.
In 2006, Project Director Sensors-Aerial Intelligence led the Guardrail Modernization Program, upgrading the Army’s RC-12 fleet to the RC-12X standard, commonly known as the Guardrail Common Sensor (GRCS). The modernization replaced aging sensors and introduced modern payloads that extended the fleet’s life by nearly 20 years. The enhancements significantly increased the frequency range and types of signals collected, enabling the system to capture and characterize signals within a fraction of a second while simultaneously processing different emitters and signal types.
Strategic Divestment
In 2022, the Army made a deliberate funding decision to prioritize aerial modernization and focus on deep sensing capabilities, aligning with future Army strategies. Deep sensing requires more capable sensors and higher flight altitudes. The higher platforms fly, the further they can collect intelligence for many sensors.
The legacy turboprop fleet had limited speed, range, altitude, power, and payload carrying capacity for deep sensing. The fleet could not meet requirements for near-peer competition.
The divestment of all three systems began in fiscal year 2023. Project Director Sensors-Aerial Intelligence divested all mission equipment packages from the legacy aircraft, while the Fixed Wing Project Office, which oversees aircraft life cycle management, completed the strategic divestment of the legacy turboprop fleet in FY25. To ensure soldiers remained supported throughout the divestment process, PD SAI, FWPO, and Headquarters Department of the Army G2 developed and executed a staggered divestment strategy. The schedule allowed several enduring systems to be divested while some were maintained in current configuration for operational use.
According to Julie Isaac, PD SAI, the Army is pivoting from 24 years of counterinsurgency operations to align with the Multi-Domain Operations fight and a modernized Army 2030 focus. A smaller fleet of aircraft that can cover much larger footprints for longer periods of time is now the way forward.
Transition to HADES
The Army began shaping the High Accuracy Detection and Exploitation System (HADES) program in 2020 to replace the legacy turboprop aircraft fleet. HADES is part of the Multi-Domain Sensing System (MDSS) program and represents the keystone of the modernization strategy for deep sensing of adversary forces and greater range capabilities.
In preparation for HADES, PD SAI partnered with FWPO to demonstrate and operationally deploy jet-based ISR sensing on contractor-owned and contractor-operated platforms. These include the Airborne Reconnaissance Targeting Exploitation Mission Intelligence System (ARTEMIS), Aerial Reconnaissance and Electronic Warfare System (ARES), and Army Theater-level High Altitude Expeditionary Next Aerial ISR Radar/SIGINT (ATHENA-R/S) jet platforms.
According to Eric Hughes, Product Manager for Multi-Domain Sensing System, PD SAI evaluates ISR sensors on demonstrator platforms to inform HADES program requirements and collect feedback about how the sensors operate on demonstrator jets at the altitudes, speed, and ranges that HADES is expected to perform.
These aerial ISR bridge systems allow the Army to rapidly innovate and accomplish interim objectives, including continuing to meet operational requirements, transforming formations and intelligence infrastructure to exploit HADES capability, and establishing initial quantities of trained aircrews for the transition. As HADES program-of-record capabilities are fielded, these bridging systems will be retired.
In 2023, the Army selected L3Harris and MAG Aerospace for ATHENA-R and Sierra Nevada Corporation for ATHENA-S. In May 2025, SNC announced successfully completing the initial Flight Performance Handling and Qualification test of the Bombardier Global 6500 business jet in the RAPCON-X (Rapidly Configurable to Any Mission-X) airframe for ATHENA-S.
HADES will be incorporated into a government-owned, government-operated modern business jet aircraft. The first Bombardier Global 6500 aircraft for HADES was delivered to FWPO in 2024, with a second aircraft delivered in July 2025. The first fully developed HADES prototype system is expected to be delivered in FY26, followed by a second prototype in FY27.
HADES will provide transformational increases in speed, range, payload, and endurance for Army aerial ISR collection capabilities, supporting the Joint force to strengthen deterrence and succeed in Multi-Domain Operations. The modernized fleet will enable greater altitude for deep sensing of adversary forces and greater range to address an increasingly diverse set of challenges in an increasingly connected global threat landscape.
