On January 29, 2025, a fatal midair collision between a Bombardier CRJ-550 regional jet and an Army UH-60 Black Hawk helicopter shocked the aviation community and the nation. The incident, which occurred near Reagan National Airport in Washington, D.C., marked the deadliest commercial airline crash in the U.S. in nearly two decades. Investigators continue to piece together the events leading to this tragedy near our nation’s capital. While many questions remain in the interim, one thing is clear: technological solutions exist today that could have prevented such a catastrophe.
The Incident and DC’s Complex Airspace
The collision took place in one of the most restricted, yet at the same time congested, airspaces in the world. A complex web of commercial, military and government flights clutter Washington, D.C.’s airspace, with Reagan National Airport situated right at its heart. The area is known for its high volume of helicopter traffic, military operations and commercial aviation.
At the time of the incident, the CRJ was on final approach to Reagan National, a critical phase of flight, while the Black Hawk was conducting a training mission along the Potomac River. The helicopter was operating on UHF (ultra-high frequency) radio, while the commercial jet was on VHF (very high frequency) – a common practice in this mixed-use airspace. This means they could not hear each other.
Near Misses: Warning Signs Ignored?
The recent tragedy highlights a broader issue: near midair collisions (NMACs) have been a recurring concern in the vicinity of Reagan National Airport for years. According to FAA data, there have been at least 30 reported NMACs since 1987, with at least 10 involving military aircraft – seven of which were helicopters. This frequency of military involvement is higher than the national average, likely due to the military presence in the area. The FAA investigated each of these incidents and took remedial action to enhance safety and reduce the risk of future near midair collisions. These ranged from pilot remedial training to technological improvements and operational procedure modifications to enhance safety and reduce the risk of future near midair Collisions.
The NASA Aviation Safety Reporting System (ASRS) has also documented numerous additional reports of near misses involving helicopters and other aircraft near Reagan National. Unlike the FAA-documented incidents, ASRS consists of unverified voluntary reports, the majority of which remain uninvestigated. All of these incidents, however, underscore ongoing concerns about airspace congestion and the need for enhanced safety measures.
Transponders and ADS-B: A Patchwork of Requirements
The Federal Aviation Administration (FAA) requires all aircraft operating in this complex airspace to use transponders, which respond to radar interrogations from air traffic control (ATC). However, the situation becomes more complex when it comes to Automatic Dependent Surveillance-Broadcast (ADS-B) technology.
Automatic Dependent Surveillance-Broadcast (ADS-B) technology plays a crucial role in modern aviation safety. ADS-B Out, which automatically broadcasts an aircraft’s position and other information, is mandated in most controlled airspace. Tom Furey, CEO of Sagetech Avionics, explained, “Unlike transponders which are generally only seen by ATC with specialized interrogators, ADS-B transmitters can be visible to anyone on the ground or in the air. The significant advantage of this system is it enables a pilot to maintain awareness of other traffic with only a certified ADS-B receiver on board, providing a critical additional level of safety over solely relying on ATC to verbally provide them with traffic information.”
ADS-B Out has been required in most controlled airspace in the United States since 2020. However, surprisingly, ADS-B In, the ability to receive ADS-B signals from other aircraft, is not required, even in airspace – such as the DC swath in question – where ADS-B Out is mandatory. This discrepancy means that even if an aircraft broadcasts its position, others may not be equipped to receive and display that information.
While not confirmed, generally speaking, military aircraft such as the Black Hawk here, lack ADS-B In equipment. For operational security reasons, the military can obtain approval to operate with ADS-B transmitters turned off in certain situations. This exception in conjunction with the lack of ADS-B In on many military aircraft, can create gaps in situational awareness where the military aircraft cannot see the signals from other traffic, and other aircraft cannot receive signals from them.
TCAS: A Critical System with Limitations
Traffic Collision Avoidance System (TCAS) is another crucial safety technology. TCAS works by interrogating the transponders of nearby aircraft and providing traffic advisories (TAs) and resolution advisories (RAs) to pilots. However, TCAS has purposefully designed limitations that kick in, particularly during the final approach phase of flight.
Below 1,000 feet on final approach, TCAS enters a different mode. While traffic is still observable, RAs become automatically inhibited. Below 500 feet, oral warnings are turned off to avoid distracting pilots during the most critical phase of landing. In this incident, the CRJ was likely within this zone where TCAS warnings were suppressed.
The Fallibility of See and Avoid
The aviation industry has long relied on the see and avoid principle as a fundamental safety measure. However, this incident highlights the limitations of human visual perception, especially in complex, high-traffic environments and at night.
The human eye is far from perfect when it comes to detecting obstacles, particularly at high speeds or in low-visibility conditions. When military pilots use Night Vision Goggles (NVGs), as was likely the case in this incident, these issues become further compounded. NVGs, while enhancing visibility in low-light conditions, can narrow a pilot’s field of view, alter depth perception and reduce visibility of certain light wave-lengths. NVGs’ light amplification enables the pilot to see more airborne traffic, but the physics of the goggles nearly eliminate depth perception, making it hard to determine their distance from opposing traffic.
ACAS-X: The Next Generation of Collision Avoidance
As the aviation industry grapples with the limitations of current systems, a new technology, Airborne Collision Avoidance System X (ACAS-X), offers promise. ACAS-X represents a significant improvement over traditional TCAS.
Furey elaborated on ACAS-X: “ACAS-X, developed by MIT and Johns Hopkins on behalf of the FAA, essentially uses an aircraft’s track history and velocities to predict where both aircraft (yours and theirs) are going to be. Unlike TCAS, it is suitable for use in any type of aircraft, including rotorcraft. And it doesn’t just tell you to climb or descend. It can tell you to climb, descend, turn left, turn right, and can give you blended maneuvers around obstacles.”
ACAS-X offers several advantages over current collision avoidance technology:
- Improved collision prediction using probabilistic models
- Ability to provide more nuanced advisories, including horizontal maneuvers
- Compatibility with various aircraft types, including rotorcraft and uncrewed systems
- Reduced false alarms, potentially by up to 50% or more
Despite these benefits, the certification and widespread adoption of ACAS-X have been slow. Industry experts argue that expediting the certification process and encouraging adoption through regulation, coupled with financial incentives, could significantly enhance aviation safety.
Sagetech Avionics: Advancing Aviation Safety
Sagetech Avionics, a leading company in aerospace safety technology, offers products that could have been instrumental in preventing this type of incident. The company’s MX12B transponder, certified for both civil ADS-B (In and Out) and military dentification Friend or Foe (IFF) applications, provides critical situational awareness capabilities in a compact form factor.
Furey additionally explained the company’s ACAS-X family of products, which includes different versions tailored to specific aircraft types:
- ACAS-Xa for large transport aircraft
- ACAS-Xo for special operations like parallel runways
- ACAS-Xu for large fixed-wing drones
- ACAS-Xr for rotorcraft
- ACAS-sXu for smaller drones (less than 55 pounds)
“Our ACAS-X family is a hardware platform that has military or civil interrogators and other things on a circuit card,” Furey said. He continued “We have a prototype of a single circuit card version of the Xu family for drones and an Xr version for rotorcraft. There is also a version (ACAS sXu) with only passive receivers for use in small drones. It could also be outfitted to recognize remote identification signals. Basically, it will be a one-stop-shop situational awareness tool.”
These technologies, if widely adopted, could significantly enhance the safety of both military and civilian aircraft operations in complex airspaces like Washington, D.C.
Military Applications and Challenges
The DC incident highlighted the need to upgrade military aircraft with modern awareness technologies. But other events, such as Jordan Tower 22, have also brought to light that traditional military operational environments cry out for additional tech as well.
According to Furey, the use of Mode 5 (an encrypted version of Mode S) and Level 2 broadcast (encrypted ADS-B) can provide secure identification of friendly aircraft. However, challenges remain in distinguishing between friendly and potentially hostile drones in congested combat airspace. He highlighted the increasing complexity of modern combat airspace. “Think about combat airspace today. Well, we know the airspace over Gaza and in Ukraine is very different, much more congested, much more crowded, when compared to the combat airspace during the Gulf War,” he said. “The risk of shooting down your own assets, or mistaking a hostile aircraft for a friendly like Tower 22, continues to increase exponentially.”
To address these challenges, Furey suggests prioritizing the upgrade of legacy fleets to current standards, implementing proper IFF systems and automating counter-UAS capabilities. He also emphasized the need for collaboration across the industry to develop and implement these advanced safety systems.
The Path Forward: Technology and Policy
As Furey aptly put it, “2025 is going to be the year of collaboration for the aviation industry.” This collaboration between technology providers, regulators and operators will be crucial to implement the next generation of aviation safety systems and prevent future tragedies, at home and abroad. The technology to help prevent midair collisions already exists. So does the ability to detect friend or foe. The challenge now lies in ensuring its widespread adoption and effective implementation across the complex tapestry of modern aviation.
By: Dawn Zoldi (Colonel USAF, Ret.)