Standardization News

Package delivery. Infrastructure inspection. Traffic management. Search and rescue operations. And someday — cue “The Jetsons” theme song — maybe even your own trips around town. When it comes to unmanned aircraft systems (UAS), the sky is most emphatically not the limit. It’s the starting point for a new world of exciting possibilities.

Tasks like those listed here (and many more) could become simpler thanks to the speed, flexibility, and birds-eye perspective provided by UAS. And in fact, “someday” is right around the corner. From Amazon and Walmart to utilities and emergency-response teams, organizations have been exploring the potential of drones for years, and in some cases, have already begun using them in limited pilot programs.

However, a number of interrelated issues need to be resolved before this technology can realize its full potential, including digital identification protocols for unmanned aircraft, real-time coordination between UAS service supplier and traffic management systems, and the ability to safely operate unmanned aircraft remotely.

READ MORE: Drones Move Into the Mainstream

Part of ASTM International’s committee on unmanned aircraft systems (F38), the subcommittee on flight operations (F38.02) is working on several key standards that will help address these concerns.

Crowded Skies

As implementation of UAS initiatives continues to expand, a tipping point will eventually be reached at which there are more aircraft in the sky operating without pilots than with them. Some of F38’s most important work is in the area of inter-system communication and digital-visibility standards that are designed to maintain a safe aerial environment.

“If you look at traditional air-traffic management, the people in the control tower are monitoring all the traffic and providing separation services,” says Amit Ganjoo, founder and president of ANRA Technologies and a member of the subcommittee on flight operations. “That was fine for crewed or legacy manned aviation, but when you move to the uncrewed world, the scale is different. Currently, you have around 10,000 aircraft in the sky at a given time. When you move to an uncrewed world, you’ll eventually have hundreds of thousands, if not millions, in the sky.”

As these numbers explode, the air traffic control system will inevitably transform from its current centralized approach and “human-in-the-loop” to one that also accommodates multiple actors and human-in-the-loop for traffic management. Two years in the making and approved last fall, a new standard is designed to facilitate the complex choreography that will keep a more crowded airspace safe for everyone.

The specification for interoperability of UAS traffic management (UTM) and UAS service supplier (USS) systems (F3548) is the standard in question. As Ganjoo explains, “This UTM-USS interoperability standard makes sure that, as all flights are strategically coordinated, the people and systems operating in the area know who they need to talk to and how talk to them, and that they talk to them in a digital format in real time.”

In response to the constant evolution of UAS technology, both in the United States and around the world, work has already begun on the next iteration of the standard, with the goal of circulating it within a year or so. International developments are helping to set the agenda.

“This is a global standard, it’s not just being used in the U.S.,” says Ganjoo. For example, F3548 is viewed as a potential means of compliance for some aspects of U-Space, the European framework for managing drone traffic that takes effect in January 2023. “Right now, we are mapping how the standard helps meet some of those U-Space requirements and identifying where gaps exist.”

Ganjoo points out that additional updates under consideration for the next version of the standard are being viewed through the prism of safety case analysis. “There are different services in this standard, like constraint management, conformance monitoring, strategic coordination,” he says. “How does each of these services add to the safety case of the flight operation?” Other concerns focus on facilitating fair, equitable use of the airspace and improving USS hygiene by creating mechanisms to deal with malfunctioning systems. 

Standards like F3548 enhance the safety of a drone mission because even before the aircraft takes off, there’s a very high level of confidence that the flight will be deconflicted, meaning there is no other traffic in the area. “But there’s still potential for unknown traffic, and then that moves into adding additional safety layers like detect and avoid (DAA) or surveillance data sources in real time that identify traffic that wasn’t known before you planned the flight,” Ganjoo adds.

It’s worth noting that a standard specification for detect-and-avoid system-performance requirements was developed by the subcommittee on airworthiness (F38.01) and approved in 2020.

UAS traffic management (UTM) and beyond visual line of sight (BVLOS) flight are two of the biggest challenges facing the industry.

Keeping Track

The crucial importance of uniquely identifying every unmanned aircraft is reflected in the work that went into establishing the newly revised standard specification for remote ID and tracking (F3411). In his role as chair of ASTM’s Remote ID work group, Gabriel Cox, a principal engineer at Intel, was part of that effort from the beginning.

After the December 2017 publication of a report by the U.S. Federal Aviation Administration (FAA) Remote ID Aviation Rulemaking Committee, it was clear to the UAS community that a standard would be needed. The ASTM work group was assembled about six months later, and published the initial version of F3411 in December 2019.

By January 2021, the FAA issued its final remote ID rule (known as FAR part 89), and Cox’s group got back to work.

“The primary impact of FAR part 89 is that manufacturers have to ensure that every UAS over 250 grams manufactured after September 16, 2022 is compliant, meaning that all covered UAS will have either Bluetooth or Wi-Fi implementation of remote ID that will transmit the ID, location, and altitude of the UAS aircraft and control station,” says Cox. “A year later, all UAS operators will be required to comply as well.”

Cox goes on to explain that FAR part 89 also contains certain requirements that went beyond the first version of the standard, such as tamper resistance, location accuracy requirements, pre-flight self-test, monitoring, and emergency status indication. Test methods that must be used to demonstrate that an unmanned aircraft complies with the rule’s requirements were spelled out as well.

The challenge? Without a standardized means of compliance (MOC), each drone manufacturer would have to develop their own MOC for each drone product they wish to declare and convince the FAA to accept it before that maker could submit declarations of compliance (DOC) for those products.

“This process can be quite arduous,” Cox notes, “So ASTM took on the task of making it easier.” The result is a new standard practice for remote ID means of compliance to Federal Aviation Administration regulation 14 CFR Part 89 (F3586), which references F3411 and was approved in April.

Cox emphasizes the importance of an industry consensus standard in a global airspace environment where regulatory requirements are being established by the U.S., Canada, the European Union, Japan, and other countries around the world seeking to meet the challenge of managing UAS traffic.

“It would be fair to think of F3411 as a ‘protocol and transmission standard’ covering the bits and bytes and the way they are sent,” he says. “It’s intended to be usable by any international constituent, primarily government civil aviation authorities. F3586 references the updated standard and adapts it to requirements that are very specific to the FAA.” Cox and his colleagues expect these standards to make life easier for large UAS manufacturers facing the burden of submitting multiple MOCs and to help level the playing field for smaller competitors.

Another benefit of F3586 is that, while it does not directly prescribe receiver requirements, it does clearly describe how the data must be transmitted. Therefore, it is inherently useful to engineers who need to incorporate this functionality into the receivers they design.

Out of View

For drones to realize their full potential, they must be able to fly safely beyond the ability of the operator to see the aircraft. In industry parlance, this concept is known as beyond visual line of sight, or BVLOS.

Industry stakeholders recognized early on that establishing BVLOS standards would be crucial for the growth of the industry. The result was the 2018 formation of administrative committee 478 (AC478) on strategy and road-mapping for BVLOS.

Phil Kenul is the chair of F38 and a member of AC478. The independent consultant describes the committee’s mandate as “establishing a flexible and modular set of standardized requirements that can be implemented by UAS industry manufacturers and operators as part of a broader effort to establish a standards-based path to widespread BVLOS operations.” Kenul cites long-line linear infrastructure inspections, industrial aerial data gathering, small package delivery, and precision agricultural operations as areas where the ability to fly beyond sightlines will be particularly valuable.

“One of the more important aspects of BVLOS is airspace situation awareness by all users of that airspace,” Cox says. “BVLOS operations could be a good bit like Instrument Flight Rules operations in the manned aviation world, where active instrumentation, tracking, messaging, and planning replace visual tracking for airspace awareness and deconfliction.”

Approximately 20 essential functions have been identified as requiring standardization in order to provide a solid foundation for UAS to be operated BVLOS. A proposed standard currently in development defines three of these functions.

The specification for positioning assurance, navigation, and time synchronization (PNT) (WK75923), which has been under development since March 2021, “will establish requirements, performance measures, and a new classification scheme for communicating information about the performance of these functions,” explains Adam Morrison, owner and CEO of Streamline Designs LLC and a member of the subcommittee on flight operations. “It is intended to provide a common basis across the industry for communicating the performance of these functions in UAS and could involve safety cases for regulators or procurement activities between manufacturers and vendors.

READ MORE: Autonomous Flight

“PNT underpins, to some degree, nearly every operation in aviation, whether it is manned or unmanned,” Morrison says. “As the prevalence of UAS increases and the integration of UAS into the shared airspace increases, it is essential that all the operators sharing the airspace can speak a common language.”

WK75923 is slated for a vote by the full committee this summer, with the hope of publishing an approved version by the end of the year. Morrison stresses that it was crafted with maximum flexibility in mind.

“The proposed standard does not prescriptively impose any particular technologies or protocols,” he affirms. “This is important as the industry is developing rapidly and it is desirable to allow many technologies or procedural solutions so long as they communicate in a compatible manner. The intent of the standard is to remain technology agnostic while still defining a useful and practical specification framework for PNT concerns.”

Beyond the Horizon

Much has been accomplished in the development of UAS-related standards, but a lot still remains to be done.

Morrison sees a number of “relatively untouched” areas that need attention going forward, including third-party services, contingency alerts and planning, automation and autonomy, and weather. He also believes the industry and regulators together need to find a way to see that consensus standards become the primary mechanism for the implementation of intent-based or performance-based rules: “Standards can operate in rapid innovation cycles focused on safely implementing technologies that occur between less-rapid regulatory cycles that focus on ensuring safety.”

Cox suggests that future standards could be beneficial in operations like projectile deployment (scattering seeds or fish larvae, among other agricultural and forestry use cases), autonomous swarm/formation flight, artificial intelligence integrity, and integration of radio communications between unmanned aircraft and manned users of the NAS.

Raising the ceiling under which UAS can be used is something that Ganjoo says is already happening. “For example, when we started the F3548 standard it was focused predominantly on small drones flying below 400 feet. Now, when you think about flying cars, advanced air mobility, things like that, we are moving from 400 feet to go maybe up to 1,000, 3,000 feet — and this requires integration into the legacy crewed aviation system. This is operating at higher altitudes, and it introduces its own set of challenges.” ■