Safe and Secure Operations of Small Unmanned Aircraft Systems (Advance Notice of Proposed Rulemaking, 84 FR 3732)

The Policy


The Federal Aviation Administration (FAA) issued an Advance Notice of Proposed Rulemaking (ANPRM) on Unmanned Aircraft Systems (UAS) raising questions regarding stand-off distances, payload restrictions, and altitude, airspeed, and performance limitations of UAS. This ANPRM was issued in response to concerns about the safety and security of integrating UAS into the National Airspace System (NAS).

Small UAS (sUAS), also known as drones, do not require a human aboard to operate. Their small, lightweight design enables these systems to have superior performances, such as improved maneuverability and speed, compared to conventional aircraft. These enhancements make sUAS useful for recreational, commercial, and governmental applications, but also provide a potential channel for exploitation. As the organization responsible for regulating civil aviation, the FAA is interested in public comment on these specifications. More explicitly, the FAA asks for comments related to:

  • stand-off distances: “the amount of space between a sAUS and the closest person or object”;
  • payload restrictions: rules regulating the cargo transported using sUAS;
  • altitude, airspeed, and performance limitations: limits on how high and fast sUAS can operate

sUAS are controlled remotely by an operator, meaning they are more easily navigated in tight corridors and over people. The FAA is concerned about the operation of these systems in close proximity to objects and people due to risk of collisions. In an attempt to regulate this, the FAA is accepting comments on stand-off distances. In addition, sUAS have the ability to be used as an efficient transporter of goods. A 2016 report by McKinsey & Company projected that 80% of all packages will be delivered by autonomous sUAS by 2026. This ability to efficiently transport goods can be used to carry dangerous materials. The FAA is open to comments on other payload restrictions for their new policy. Lastly, the compact design of sUAS means these systems can travel at extraordinary speeds and at altitudes similar to commercial aircraft. These capabilities enhance the performance of sUAS but also pose a risk to other systems in the NAS, existing infrastructure, and humans on the ground. The FAA is continuing to assess limitations on airspeed and altitude to reduce these risks.


The FAA Modernization and Reform Act of 2012 sought to determine which UAS pose a risk to the public or to national security. This act projected to “develop and implement operational and certification requirements for the operation of public unmanned aircraft systems in the national airspace system” no later than December 31, 2015. The FAA began studies by granting government entities a Certificate of Waiver or Authorization (COA) to operate UAS. Between 2012 and 2014, the FAA issued over 1,200 COAs and in November 2013, the Department of Transportation (DOT) and FAA released their first Integration of UAS in the NAS Roadmap, which “[outlined] the actions and considerations needed to enable UAS integration into the NAS.” The DOT and FAA issued an ANPRM in February 2015 addressing the operational and certification requirements of sUAS to enter the NAS. On June 28, 2016, this APRM finalized to become the Operation and Certification of Small Unmanned Aircraft Systems. In summary, these sUAS provisions include:

  • must weigh less than 55 lbs
  • may only be operated within the pilot’s visual line-of-sight (VLOS)
  • may not be used over any person not covered by a structure
  • may only be operated during the daytime
  • maximum groundspeed of 100 mph and altitude of 400 feet above ground level

Following the introduction of the Operation and Certification of Small Unmanned Aircraft Systems, many federal and private stakeholders supported the expansion of commercial sUAS operations. The FAA “[anticipated] an increased demand for flexibility in operational restrictions” as novel applications in recreational, federal, and commercial fields were identified. McKinsey and Company reported that the drone industry increased from $40 million in 2012 to $1 billion in 2017. According to the report, these systems are used in five main categories:

  • surveillance: conducting short- and long-range surveillance, image capture, and photo and video applications;
  • operations: “facilitating labor-intensive or difficult tasks”;
  • entertainment/advertising: “leveraging drones to entertain or advertise”;
  • signal emission: “providing multimedia bandwidth by emitting signal/video/sound”;
  • movement: transportation of people or delivery of objects

As a result of the growing interest in UAS, McKinsey and Company estimates the commercial drone industry can grow to $20 billion by 2026. Project X-Wing, owned by Google’s parent company Alphabet, argues that UAS can “increase access to goods, reduce traffic congestion in cities, and help ease the CO2 emissions attributable to the transportation of goods.” According to McKinsey & Company, UAS start-ups have received over $3 billion in funding due to the promise UAS hold. This promise is contingent on flexibility in operational and certification regulations of these systems.

Before the FAA could proceed with amending the current restrictions, comments on the risks associated with public safety and national security are requested by the Administration. Accordingly, the FAA issued this ANPRM to seek comment on safety and security of UAS expansion.


The FAA is also addressing Executive Order (EO) 13610, which urges agencies to reduce unjustified regulatory burdens and costs through “retrospective analyses of existing rules”. On the similar topic, President Trump’s Executive Order 13771 aims to reduce regulation and regulatory costs by requiring agencies proposing a policy to identify two existing regulations to be repealed. This EO also requires that costs of proposed regulations are carefully budgeted. In addition, EO 13771 and Executive Order 13563 require public participation in proposed rulemaking, and the FAA is looking for comments on their proposed rules.

The Science

Science Synopsis


Unmanned Aircraft Systems (UAS) are defined as any flying machine that is not piloted by a human aboard the system. These systems mainly present as winged aircrafts or copters, but UAS encompass all aircraft systems that are unmanned. The most common UAS are small UAS (sUAS), also known as drones, are characterized as being less 55 pounds including everything on board. UAS operate either by remote control of a human or by autonomous systems. These devices can be used for recreational purposes as well as commercial, federal, and educational operations. Some examples include using drones to capture photos or videos, deliver packages, and aerial imaging and mapping. In the US, drones operate in the NAS.

The National Airspace System is comprised of “a network of air navigation facilities, air traffic control (ATC) facilities, airports, technology, and appropriate rules and regulations that are needed to operate the system.” Operation in the NAS is dependent on aircraft type, weather, and flight rules. Under the ATC, the Unmanned Aerial Systems Traffic Management (UTM) ensures the safe operation of UAS. UTM systems are a network for “communication and coordination between the FAA, UAS operators, and other stakeholders…through automated systems”. This is accomplished through services such as:

  • airspace design: the designation or restriction of specific portions of the atmosphere for operations
  • corridors: sub-sections of an airspace that an aircraft is restricted
  • geofencing: a means of overriding UAS operations to restrict flight navigation
  • weather and wind avoidance: the coordination with meteorological monitoring systems to prevent severe weather and wind impediment
  • congestion management: mitigation of risks associated with increased UAS use
  • terrain and collision avoidance: assistance to ensure that UAS can sense and avoid obstacles
  • route planning, re-routing, and location management: directions given by the UTM to determine appropriate location, speed, spacing, and sequencing of all UAS
  • contingency management: anticipation of and reaction to possibility of deviating from flight plans

Safety and Security

The main concerns regarding the expansion of sUAS operational guidelines are related to public safety and national security. sUAS can cause physical damage and harm by colliding with other systems operating in the NAS, crashing into existing infrastructure, or hitting a person on the ground.

Through simulations, studies have found that sUAS can cause significant damage to a commercial or business aircraft upon collision. Extensive research has been conducted on the impact of bird collisions into aircrafts. These wildlife-collision studies found that bird collisions “have resulted in the loss of hundreds of lives worldwide, as well as billions of dollars in aircraft damage.” sUAS collision studies determined that sUAS cause more damage than birds of an equivalent size and speed due to the material build of sUAS.

sUAS can also cause damage by crashing into infrastructure. In Mountain View California, a drone crashed into a power line that supplied power to over 1,600 people. Residents were left without power for three hours, and the City Hall and the main library were also affected. This resulted in tens of thousands of dollars in repairs.

The FAA studies on sUAS human collision hazards identified three main injury types caused by these systems: blunt force trauma, lacerations, and penetration injuries. In 2017, a drone crashed into a building during Seattle’s Pride Parade and fell into the crowd. It ended up striking a woman’s head resulting in a concussion. The operator of the drone was fined $500 and sentenced 30 days in jail.

Aside from public safety, sUAS also have the potential to pose threats on national security. Drones allow operators to remotely monitor locations, which can be useful but also used for espionage. Terrorist organizations can use drones to gather intelligence and conduct attacks as these systems become more advanced. These systems can also be used to gather sensitive intellectual property information. sUAS may also be used to transport contraband or explosives. The FAA has noted that sUAS have been used for “illegal surveillance and industrial espionage; to deliver contraband to prison inmates; to deliver incendiary, explosive, chemical, and radiological payloads; to damage or disrupt critical infrastructure…; and to conduct malicious cyber activity.”

Stand-off Distances

The FAA defines stand-off distances as “the amount of space between a [sUAS] and the closest person or object.” In other words, it is the minimum distance between a sUAS and another person or object in a horizonal or vertical component. Currently, sUAS do not have any stand-off distance restrictions, meaning sUAS are permitted to be as close to a person or object as the operator desires. Remote pilots are only required to follow general guidelines to reduce risk. This includes avoiding flight directly over any person not protected by a covered structure. The FAA acknowledges that stand-off distances can be burdensome, but they also provide measures to mitigate safety and security concerns when sUAS are operating too closely to people or buildings.

Payload Restrictions

Payload describes the carrying capacity of aircraft systems. UAS are a convenient method to carry goods. For example, Amazon Primer Air began trials with autonomous sUAS in 2016. McKinsey & Company expect these small-scale projects to expand in the next five to ten years. They also project 80% of all parcels to be delivered by autonomous sUAS by 2026.

The use of sUAS as a transporting mechanism can revolutionize the commercial sector, but these carrying capacities can also be dangerous depending on the goods carried. The FAA has noted instances where sUAS were used to “interfere with law enforcement, firefighting, and aviation operations.” Current restrictions on payloads address hazardous materials such as chemicals or hazardous waste; however, the FAA is considering amending this to include other types of payloads and defining conditions under which specific payloads would be restricted.

Altitude, Airspeed, and Performance

sUAS are constructed from light, durable materials. This enables them to have performances superior to conventional aircraft systems. For example, some sUAS “are capable of speeds in excess of 150 knots (172 mph), altitudes of 10,000 feet or more, and climb rates in excess of 6,000 feet per minute. Some can accelerate from 0 to 60 mph in less than 1 second.” Their small size means sUAS can be operated in tight spaces not accessible by traditional aircrafts or in closer proximity to people or infrastructure. The current restriction on sUAS performances are “a maximum groundspeed of 87 knots (100 mph) and a maximum altitude of 400 feet above ground level, unless operated within a 400-foot radius of a structure, in which the case is 400 feet above the structure’s uppermost limit.” Implementing restrictions on sUAS performances would prevent these systems from becoming overly hazardous.

Scientific Assumptions

The underlying assumption of this ANPRM is that drones may cause risk to the public and to national security. Since sUAS are relatively novel technologies, insufficient research has been conducted on the safety of these systems. The FAA determined “which types of UAS do not create a hazard to users of the NAS or the public or pose a threat to national security” following the FAA Modernization and Reform Act of 2012. Given this, the FAA is still hesitant to promulgate modifications in their current guidelines for sUAS operations as defined outlined in the Operation and Certification of Small Unmanned Aircraft Systems. More research and public input are needed, and this ANPRM pursues the latter.

Relevant Experts

Michail Zavlanos, Mary Milus Yoh and Harold L. Yoh, Jr. Associate Professor in Mechanical Engineering and Materials Science, Pratt School of Engineering. Dr. Zavlonos specializes in networked control systems with a focus in flying and communication maintenance of robotic and sensor networks. The Challenge: Controlling Drones After You Lose Communication With Them

Mary “Missy” Cummings, Professor in the Department of Mechanical Engineering and Materials Science. Her research interests include human-unmanned vehicle interaction, human-autonomous system collaboration, human-systems engineering, public policy implications of unmanned vehicles, and the ethical and social impact of technology.

Charles J. Dunlap, Jr., Professor of the Practice of Law. Dunlap focuses on national security and ethical issues related to the practice of national security law.

The Debate

Scientific Controversies / Uncertainties

Uncertainties of integrating UAS into the NAS include stand-off distances, altitude, airspeed, and performance limitations, unmanned traffic management (UTM) operations, payload restrictions, and critical system design requirements. Insufficient research has been conducted on these issues, and for this reason, the FAA is opening public comments to address these uncertainties. Specifically, the FAA asks these questions:

Stand-off Distances

  • “What types of operations, if any, should be excluded from a proposed stand-off distance requirement and why?
  • How would a horizontal or vertical stand-off distance requirement help reduce hazards to public safety and national security?
  • What are the incremental costs of introducing a stand-off distance requirement compared to how operations are conducted today?
  • Does requiring a minimum stand-off distance necessitate additional instrumentation? If yes, provide costs and other relevant information.
  • If minimum stand-off distances are required, would training or testing be necessary? If yes, provide estimate of time and cost.”

Altitude, Airspeed, and Other Performance Limitations

  • “If the FAA were to establish additional operating or performance limitations for [sUAS], what should those operating or performance limitations be and why?
  • If the FAA were to establish additional operating or performance limitations for only certain types of [sUAS] operations, what types of [sUAS] operations should require additional operating or performance limitations, what should they be, and why?
  • How would additional operating or performance limitations help to reduce risks to public safety or national security?
  • What type of current [sUAS] operations would be impacted by establishing additional operating or performance limitations?
  • What are the incremental costs of altitude, airspeed, and other performance limitations?”

Unmanned Traffic Management Operations

  • “How can additional information sharing (e.g., intended flight path, operational boundary) via UTM help reduce risks to public safety and national security? What suite of capabilities should UTM have?
  • What types of small UAS operations should be subject to UTM requirements? Should any be excluded? Should the requirement be based on geographical location, the type of operation, or other factors? Please provide data or explanations to justify your response.
  • For small UAS subject to UTM requirements, what type of information should be available to the general public? What type of information should be available to security personnel?
  • What are the initial nonrecurring investment costs associated with establishing a UTM architecture? Once implemented, what are the annual recurring operation and maintenance costs?
  • Would additional testing or training be required for a remote pilot to safely operate a small unmanned aircraft subject to UTM requirements? Please explain.
  • What would be the costs for information sharing if UAS operations are subject to UTM requirements?”

Payload Restrictions

  • “Should the prohibition from carrying hazardous materials…be expanded to include other types of payloads or installed equipment that could pose a threat to public safety or national security? If yes, what types of payloads should be prohibited and why?
  • Should the FAA consider rulemaking to restrict the use of certain types of small UAS payloads or installed equipment? If yes, what types of payloads should be restricted, under what conditions should they be restricted? Should there be exceptions or special provisions applicable to certain conditions or other factors such as location, time, population density, or purpose? Please provide data or explanations to justify your response.
  • What types of operations would be affected if additional restrictions are placed on the type of payloads and equipment that can be installed on a small UAS? Would there be any costs or lost revenues associated with those restrictions?”

Small UAS Critical System Design Requirements

  • “For small UAS operations beyond the visual line of sight of the remote pilot, should the FAA establish design requirements, such as redundancy, for systems critical to safety of flight? If yes, what should these requirements be and why? Are there other means the FAA should consider to address public safety and national security risk for [beyond visual line of sight] BVLOS operations?
  • For small UAS operations over people that exceed the NPRM safety thresholds indicated above and therefore still must seek a waiver…to operate over people, should the FAA establish design requirements, such as redundancy, for systems critical to safety of flight? If yes, what should these requirements be and why? Are there other means the FAA should consider to address public safety and national security risk for operations over people?
  • Are there other types of small UAS operations besides BVLOS and operations over people that the FAA should establish design requirements for, such as redundancy, to address public safety and national security risk?
  • What are the costs and benefits to incorporate redundant systems critical to safety of flight for BVLOS operations or operations over people that exceed the NPRM safety thresholds indicated above?”

Endorsements & Opposition

Proponents of Integration

American Civil Liberties Union (ACLU), letter to Congress, June 6, 2018: “While the potential security threat posed by drones is real and the need to protect certain facilities is legitimate, strong checks and balances to protect property, privacy, and First Amendment rights are vital. S.2836 [a bill “ to assist the Department of Homeland Security in preventing emerging threats from unmanned aircrafts and vehicles”] lacks such measures. The bill amounts to an enormous unchecked grant of authority to the government to forcefully remove drones from the sky in nebulous security circumstances.”

National Academies of Sciences, Engineering, and Medicine (NASEM), news report, June 11, 2018: “Introducing drone operations into the nation’s airspace can provide substantial benefits to society, such as preventing derailments, inspecting cell phone towers, delivering medical devices to patients in cardiac distress, and assisting firefighters, says a new congressionally mandated report by the National Academies of Sciences, Engineering, and Medicine. However, an overly conservative approach to safety risk assessments at the Federal Aviation Administration (FAA), which the report says tends to overestimate the severity and likelihood of risks from many types of drone operations, can be a significant barrier to introduction and development of this emerging and rapidly changing technology.”

Association for Unmanned Vehicle Systems International (AUVSI), statement, January 14, 2019: “These FAA rulemakings will help advance the commercial UAS industry beyond the current regulatory framework. Expanded operations such as operations over people are currently allowed through the FAA’s waiver process on a case-by-case basis, and CNN and State Farm are among the companies already conducting these flights safely. A rule that allows for widespread operations over people without requiring a waiver will allow more operators to harness the great potential of UAS. The FAA’s separate call for comments on a proposed rule concerning operational limitations, airspace restrictions, hardware requirements, and associated identification and tracking technologies will further shape a national UAS policy. We are very encouraged by the announcement of these proposed rulemakings, and AUVSI welcomes this opportunity to provide comments on these policies, after our members have reviewed and analyzed them, to continue to move the industry forward.”


Safety Concerns

Lisa Ellman, co-executive director of the Commercial Drone Alliance, op-ed, December 19, 2017: “…to integrate the airspace properly, and in a way that is safe and secure, basic ‘rules of the road’ are necessary. Just like the highways we traverse every day in cars and trucks, it is critical that all vehicles navigating ‘highways in the sky’ participate in the broader drone ecosystem. Policy and regulations defining these rules of the road, combined with technology able to assign drones a ‘license plate,’ are a necessary step to expand commercial drone operations…It is critical to consider the benefits of commercial drone integration, in addition to safety and security, as the FAA decides whether to actually scope out model aircraft from a remote identification and tracking requirement. The future of the commercial drone industry in the United States depends on it.”


James Mattis, Defense Secretary, Congress meeting, September 5, 2018: “The problem is it’s only a matter of time before the threat manifests in a violent way…We are going to have to come in with a very clear statement of what we need from the Congress or the FAA and then get that authority out, get the systems out to take them down.”


Edward J. Markey, Senator, press release, January 15, 2019: “Drones have the capability to collect treasure troves of sensitive personal information using technologies like facial recognition and automated license plate readers, yet the FAA has failed to establish any baseline privacy protections, despite its obligation to integrate drones into the national airspace. This neglect of American’s right to privacy in the age of drones is unacceptable. Congress must man the controls, which is why I will be reintroducing my Drone Aircraft Privacy and Transparency Act to protect the public from these potential flying spies in the skies.”

Potential Impacts

According to AUVSI, the FAA policy to modify current sUAV regulations to be more flexible will help advance society. “A rule that allows for widespread operations over people without requiring a waiver will allow more operators to harness the great potential of UAS.” AUSVI specifically highlights State Farm and their permission to fly drones BVLOS and over crowds of people. State Farm was granted this waiver from the FAA to assess damages following Hurricane Michael. “State Farm requires the ability to quickly assess damage after significant weather events in order to serve customers as efficiently as possible. Drone technology is an additional tool providing technical capabilities to quickly deploy over an event site and assess damage from the air.”

On the other hand, Senator Markey raises concerns about privacy and safety. He believes that making sUAVs more accessible without consideration of privacy protections is a “neglect of American’s right to privacy.” He plans to reintroduce his Drone Aircraft Privacy and Transparency Act, a bill to amend the FAA Modernization and Reform Act of 2012, to “protect the public from these potential flying spies in the skies.”