why it matters
Unmanned aircraft systems, or “drones,” can pose safety and security risks to critical US sites and can be used for smuggling or other criminal activities. With more than 2 million drones expected in the United States by 2024, these risks are expected to increase. Detection and mitigation technologies could counter these risks, but could face problems with effectiveness and unintended impacts.
What is that? Unmanned Aircraft Systems (UAS), or “drones,” have a variety of uses, such as photography, package delivery, and crop monitoring. However, UAS can also pose significant safety and security risks if they enter the airspace around critical US sites without authorization or are used for illegal activities. To reduce these risks, anti-UAS technology can detect these unauthorized or dangerous UAS and, if necessary, block, capture or disable them.
Several UAS incidents have been reported in the United States. For example, in January 2019, Newark Liberty International Airport halted all landings and diverted planes for over an hour after a potential UAS sighting nearby. Additionally, smugglers have used UAS to deliver illegal drugs into the country (see Fig. 1).
Figure 1. Some of the risks posed by unmanned aircraft systems.
Reported incidents like these may increase as the use of UAS increases. The Federal Aviation Administration (FAA) has projected that by 2024, the commercial UAS fleet will grow to around 828,000, and the recreational fleet will number around 1.48 million.
At the national level, counter-UAS activities may be restricted or prohibited by existing federal laws such as the Aircraft Sabotage Act or the Computer Fraud and Abuse Act. However, four federal agencies – the Departments of Defense, Energy, Justice, and Homeland Security – have been authorized to deploy anti-UAS technologies under certain circumstances, such as to protect sensitive government facilities, including including national military bases and prisons, or to provide security at sports championships.
How it works? Anti-UAS technologies generally fall into two categories: detection and mitigation. Detection technologies include infrared devices to track heat signatures, radio frequency systems to search for command signals, and acoustic methods to recognize the unique sounds produced by UAS engines. According to a 2019 Bard College report, radio frequency and radar systems are the most common detection technologies (see Fig. 2).
Figure 2. In this example, a critical site detects an unauthorized UAS nearby. An interfering signal scrambles the connection between the UAS and its operator to redirect the UAS away from the site.
Mitigation technologies can repel or intercept an unauthorized UAS. For example, interfering signals may jam or break the communication connection between the UAS and its operator, which may trigger the UAS to land or return to its operator. According to the Bard College report, jamming is the most common mitigation technology. Other mitigation technologies may use net or kinetic force (such as lasers or projectiles) to disable or destroy the UAS. However, kinetic methods can be problematic because a falling or exploding UAS can cause unintended damage.
How mature is it? Although the Department of Defense has used anti-UAS technology overseas since at least 2014, domestic use has been limited. Over the past 4 years, authorized agencies have deployed certain anti-UAS technologies domestically. However, some of these technologies have a limited ability to detect and track small UAS (less than 55 pounds). Additionally, few are successful in jamming or disabling a UAS, and many who can are only effective at around 1,000 feet or less.
To address UAS risks, the FAA (which has been authorized to conduct limited testing activities) and authorized agencies continue to test, evaluate, and develop integrated counter-UAS platforms. The capabilities of these platforms are designed to respond to specific risk environments. For example, a powerful long-range signal jammer can be effective in mitigating UAS in rural areas, such as near some national military bases, but this same technology could also disrupt legitimate, life-saving communications if used in a city or near an airport.
UAS technology continues to advance and become more accessible to the public. For example, UAS have become smaller and more maneuverable, making detection and mitigation more difficult. To remain effective, anti-UAS technology will need to adapt to these changes.
- Reinforced security. UAS have interfered with military and commercial air operations, entered airspace at major sporting events, illegally accessed wireless networks, and been sighted over sensitive national security installations. Anti-UAS technologies could address these threats to critical sites and assets.
- Better situational awareness. Anti-UAS platforms could enable tracking of UAS activity near critical sites and enable analysis of data over time or across locations to better understand the threat.
- Efficiency. Electromagnetic interference (eg, power lines and LEDs) and small airborne objects (eg, birds) can reduce detection capabilities or generate false detections. Mitigation systems may have limited effective range or struggle against UAS that are fast or move in unpredictable patterns.
- Unintended effects. Anti-UAS platforms can pose security risks by interfering with nearby communications, such as devices that use navigation systems. For kinetic mitigation, errant projectiles or falling UAS could damage property or injure people on the ground.
- Limited number of authorized agencies. As of March 2022, only four federal agencies are authorized to conduct counter-UAS operations under certain circumstances, and no state or local agency (or individual) has such specific federal authorization. According to the Bard College report, local agencies typically rely on a small number of federal counter-UAS units to respond to and protect against UAS threats in their area.
- Privacy issues. Counter-UAS detection methods could collect personally identifiable information, such as operator information or camera footage of bystanders.
Policy Context and Issues
With the increased use of UAS and, at the same time, the increased demand for anti-UAS technologies, the key questions for policy makers are:
- What research and development could lead to innovative counter-UAS solutions that can more effectively address UAS safety and security risks while minimizing unintended effects on airspace or the public?
- What are the potential trade-offs if policymakers consider allowing the use of counter-UAS by others, including state and local law enforcement agencies, and expanding the use of these technologies?
- If policymakers are considering expanding authorization, what is the appropriate level of jurisdictional coordination and regulatory oversight for the use of these technologies between federal and other agencies?
For more information, contact Brian Bothwell at (202) 512-6888 or BothwellB@gao.gov.