A future where remotely-piloted aircraft can be flown safely without human intervention will open new possibilities and a wide range of benefits. But while current technology has advanced rapidly toward assuring safe and reliable unmanned traffic management (UTM), disparities in airspace monitoring systems threaten the next phase of progress.

Ground-Based Detect & Avoid

This article looks at global regulatory progress and standards for collision avoidance, and the role that ground-based air monitoring (or surveillance) systems can play in ensuring safe drone operations, especially when flying beyond visual line of sight (BVLOS). This includes:

  • Radio Technical Commission for Aeronautics (RTCA)
  • ASTM International
  • US Federal Aviation Administration (FAA)
  • European Union Aviation Safety Agency (EASA)
  • Joint Authorities for Rulemaking on Unmanned Systems (JARUS)
  • EUROCAE

What technology evolution is required to fulfill these mandates, in particular the need for multiple risk mitigation systems mutually complementing each other, to provide the right level of safety for complex and autonomous remotely-piloted aircraft missions?

BVLOS flight for unmanned aircraft systems (UAS) enables repeatable, scalable and regularized operations. Detect-and-avoid (DAA) technologies, in turn, enable BVLOS ops. These routine advanced operations will require an awareness solution arguably just as complex as the airspace itself. Recognizing this, regulators and standards bodies have included ground-based surveillance systems (GBSS) as a key enabler for extended operations in all classes of airspace and for Unmanned Traffic Management (UTM). Surveillance must not only be comprehensive but unified for the industry to reach new heights.

The RTCA

The RTCA, an independent and collaborative public-private Standards Development Organization (SDO), has been working on DAA for years. RTCA Special Committee 228 has focused on larger UAS over 500 feet (ft) above ground level (AGL). It incorporated ground-based DAA (GBDAA) into several of its minimum operating performance standards (MOPS), such as 381 which includes ground radar as part of an overall traffic surveillance solution on approaches to airports.

Draft DO 381A adds en route environments and contains GBSS characteristics standards for larger UAS performing extended operations in Class D thru G airspace or transiting Class B – C airspace. According to Andy Thurling, Chief Technology Officer for Northeast UAS Airspace Integration Research (NUAIR), who contributes to RTCA standards, the group now uses the sensor-agnostic term “surveillance system.” He explains, “GBSS could include acoustic, optical, radar or other solutions – any technology that achieves the required performance.”

ASTM International (ASTM)

Whereas the RTCA’s airspace integration efforts revolve primarily around Class D airspace and higher, ASTM, another globally-recognized and consensus-based standards organization, has been looking at what Thurling, who is also the ASTM DAA Performance Requirements lead, describes as, “UTMish” airspace (mostly Class G). ASTM, another globally-recognized SDO, in F3442-20 (July 2020) DAA Performance Requirements for UTM low-level airspace includes the Airborne Collision Avoidance System (ACAS) sXu as a reference architecture that provides a single level of alerting and guidance with the separation volume scaled based on intruder type. F3442-20 and ACAS sXu also accommodate a blended solution that could include ground-based tech. RTCA and ASTM collaborate on their DAA efforts because their airspace “lanes” overlap in medium risk airspace. ASTM also strives to ensure that any surveillance system also remains technology-neutral. The updated DAA Performance Requirements standard is expected to be published in the next six months.

The Federal Aviation Administration (FAA)

The FAA’s UTM Concept of Operations (CONOPS) version 2.0., published in March 2020, aligns with RTCA and ASTM DAA standards. It includes requirements for conflict advisory, alert and surveillance as a set of strategic and tactical services to support the UTM safety case.

The European Union Aviation Safety Agency (EASA)

Also in March 2020, the EASA finalized its U-Space regulation, effective in 2023, outlining the European Union’s UTM system. It requires third-party U-space service providers (USSPs) to provide four required USSP services including traffic information services to track drones through both network and broadcast-out to other providers and operators. Traffic information services can include GBSS.

The Joint Authorities for Rulemaking on Unmanned Systems (JARUS)     

The JARUS is also working on an Annex to the Specific Operations Risk Assessment (SORA), which will provide a methodology for operators to claim “credit” for UTM services in their safety case, including surveillance services (Tactical Conflict Detection and Alerting Safety Service). It is anticipated that the Annex will, like other aspects of the SORA, focus on proportional operational risk. Expect to see GBSS concepts in the Annex.

EUROCAE

EUROCAE, a membership-based non-profit SDO, continues to develop five different standards and MOCs for the U-Space rule that relate to DAA, including on traffic Information. It remains to be seen whether or not the group incorporates GBSS in these standards consistent with all other SDOs.

The Unified Surveillance Solution

Effective DAA will require a system of systems approach. According to Thurling, “You can’t do BVLOS without a surveillance system, either on board, off board, or a blend of the two.”

Vendors such as Echodyne provide both ground-based and onboard radar solutions for traffic management and DAA. Another approach is using optical computer vision to provide robust situational information and intelligent decision-making in real time to avoid mid-air collisions. Iris Automation’s Casia system, fixed on the ground around a work area perimeter or along a traffic corridor, could also provide an area of deconflicted air space to enable UAS to safely operate.

Iris Automation CEO Jon Damush explains,

“The potential benefits of a Casia-GBSS solution extend to a range of UAS operations, from active disaster area assessment, construction sites, mining, perimeter inspections, and more. A number of standards organizations are on track to finalize key surveillance standards to help move the UAS industry forward.”

Jonathan Daniels, CEO of Praxis Aerospace Concepts International, agrees.

“We need holistic solutions and need them soon.” Daniels would take the DAA solution one step further, requiring what he has coined “unified surveillance.” “Unified communications is a term first used to describe a phone system which integrated multiple communications methods with different physical layers (WIFI, LTE and RF) to appear seamless for the user. Similarly, we need GBSS and other surveillance options to become ‘unified surveillance.’ Think of this in terms of common driving apps like Waze or Google Maps that use crowd-sourced information to inform and improve driving experiences.”

That may be happening. In February 2021, the Global UTM Association and GSMA collaborated to produce a definition that harmonizes the interfaces of data exchanges between mobile network operators (MNOs) and various aviation systems as part of the overall UTM system.

The day is near when we will effectively achieve air and ground multi-sensor fusion and integrate data from multiple other sources that communicate with each other and with the humans that need the information to make operational decisions.

References*:

http://theory.stanford.edu/~barrett/pubs/LRM+19.pdf

https://www.gsma.com/iot/wp-content/uploads/2021/02/ACJA-NetworkCoverage-Service-Definition-v1.00.pdf

UAV DACH: Beitrag im Original auf https://www.uasvision.com/2021/06/01/getting-to-unified-surveillance-the-comprehensive-detect-and-avoid-solution/, mit freundlicher Genehmigung von UAS Vision automatisch importiert. Der Beitrag gibt nicht unbedingt die Meinung oder Position des UAV DACH e.V. wieder. Das Original ist in englischer Sprache. Für die Inhalte ist der UAV DACH e.V. nicht verantwortlich.