The Federal Aviation Administration (FAA) has announced the results of its Uncrewed Aircraft Systems (UAS) Traffic Management (UTM) Pilot Program (UPP) 2 set of trials and demonstrations. Key elements of emerging UTM capabilities that will support beyond visual line of sight (BVLOS) operations were tested and although, in principle, current industry technologies for managing high density operations and strategic de-confliction were shown to be effective, there is still work to be done before they can support commercial operations.
The objectives of the programme were to test:
- The FAA flight information management system (FIMS) prototype and infrastructure, which gives the FAA access to information from industry and other stakeholders.
- New technologies and data to validate the latest standards for Remote ID and support authorized users with specific operator data.
- In-flight separation from other uncrewed aircraft (UA) or crewed aircraft in high-density airspace to validate recently proposed international UTM standards to help UA avoid each other.
- UAS volume reservations (UVRs) to notify UAS operators of emergencies and make sure other UTM capabilities work properly in these scenarios.
- Secure information exchanges between the FAA, industry, and authorized users to ensure data integrity.
According to a high level view of the programme’s conclusions:
“UPP2 was successful in examining a variety of end-to-end UTM functionalities and gathering information necessary to support initial implementation activities. While many aspects of UPP were successful, as with any demonstration of this nature areas of potential future enhancements or improvements on the process were identified. UPP partner teams provided feedback on lessons learned through the development and demonstration activities, and program-level lessons learned were also collected.”
In April 2020, the FAA selected two FAA UAS test sites to partner with the agency for UPP2 development, testing, and demonstration activities: Virginia Tech, Mid Atlantic Aviation Partnership (MAAP) and New York UAS Test Site (NYUASTS).
The following is an edited compilation of the programme’s main objectives and recommendations:
High Density Operations
UPP2 high density operational testing leveraged the findings of NASA’s UTM RTT TCL4 report as the defining goal. UPP test site partners successfully conducted demonstration activities with operational densities of 10 or more UA per 0.2 square nautical miles during demonstration flight activities.
Recommendations: Increasing density of operations served as a valuable tool for stress testing various functionalities and interoperability requirements within a cooperative traffic management ecosystem such as UTM. For example, approaches to strategic deconfliction at the time of testing presented challenges to maintaining high-density operating environments. Given altitude restrictions for UAS operations (400 feet AGL) combined with the ASTM Draft Specification for UTM of 95% containment error bounds, capacity of the airspace was limited and deconfliction was complicated. Additional requirements development/testing, followed by industry evaluations in live-flight environments, will support continued improvement to capacity and efficiency of UA operations in a given airspace.
UAS Volume Reservation (UVR)
UPP2 test goals to demonstrate UVRs were intended to determine the data exchange performance across the network, such as gathering and transmittal of operational intent, and the performance of data transmission from USS to DSS. During the demonstrations of the UVR prototype capability, USS network participants successfully proved interoperability of the system in transmitting, displaying, and notification of distributed and overlapping UVR information.
Additionally, public safety stakeholders found the capability to have value in supporting potential public safety scenarios.
Recommendations: In the near term, additional development and refinement of the UVR capability is needed, including permissions and business rules required to utilize UVRs, availability of relevant contextual UVR information, and improving how the information is transmitted, accessed, and displayed. Continued conceptual and policy efforts are needed to determine requirements that address these gaps.
Strategic Deconfliction Approaches
The goal during UPP2 was to demonstrate strategic deconfliction via advanced planning and information exchange. Both MAAP and NYUASTS partners utilized the ASTM Draft Specification for UTM and its standard API for sharing of operation intent11 as the benchmark for testing where able. Generally, demonstration of strategic deconfliction approaches were successful. The approaches broadly included coordination between UAS operators via USS-to-USS data exchanges, and strategic deconfliction where operational overlaps occurred.
Recommendation: While both strategic deconfliction and network performance supporting data exchange showed success during demonstrations, some refinement is required to expand operational use of the deconfliction approaches and the system and software prototypes developed to support deconfliction. Current draft UTM standard requirement of 95% containment presented challenges as it was often hard to achieve both deconfliction and a high-density environment given the altitude constraints currently imposed on UAS operations….Demonstration results show that additional contextual information for operators is needed for full deconfliction information sharing to be realized. Further development by industry is needed so that USS software may fully implement automated means of sharing information.
Remote Identification (Remote ID)
UPP2 goals for Remote ID were to demonstrate system performance in providing certain identification, location, and UA performance information that people on the ground and other airspace users can receive. The ASTM Specification for Remote ID, which details performance requirements for UAS Remote ID technologies and services, was utilized as the benchmark for flight test demonstrations. Overall, prototypes tested were able to successfully transmit broadcast Remote ID information at distances where the UA was difficult to visibly detect, up to 3,000 feet. Additionally, industry participants provided feedback indicating their assessment that ASTM Network Remote ID as defined in the standard can work in an operational environment and support stakeholder needs.
Recommendations: While the demonstration and research of the capability to broadcast Remote ID information was successful, the tests revealed several needed improvements requiring additional testing. Test site partners and stakeholders found that screen size should be adjusted, automatic testing of Remote ID providers is needed, Bluetooth V5 is more capable, production hardware designs require careful attention, and actual broadcast latency impacts, and considerations of spectrum analysis may need additional analysis for given areas. The demonstration of the capability to broadcast Remote ID revealed efficacy across the prototype services; however, additional testing may be required to optimize Remote ID broadcast capabilities. Automatic testing of Network Remote ID Service and Display Providers should be incorporated in future tests to ensure interoperability and compliance to the standard.
Support of Message Security
UPP enacted security measures to protect the information exchanges between the participants. UPP1 established a baseline for ensuring the authorization of participants using a central authorization server to issue access tokens that are required for any UPP communications. In addition, UPP1 required TLS protocols to be used for in-transit protection. UPP2 built upon those initial baselines to add digitally signed messages and a PKI which provided application layer protections for integrity, authentication, and non-repudiation.
Recommendations: Future implementers of UTM should consider security to be a critical enabler of the UTM concept. Participants must trust that the information they receive from other UTM participants has not been altered or corrupted. In addition, participants must trust the source of received data to use such data to inform operational decisions. The FAA, industry, standards bodies, and other UTM stakeholders should continue to evaluate the security needs for the UTM ecosystem to determine the appropriate protections for UTM data exchanges in the future.
Information Queries and Correlation
UPP2 demonstrated information queries within three categories: Correlation Query, Historical Query, and Network Remote ID Query. Each was demonstrated and tested with the purpose of determining the data exchange/query performance. The Correlation Query returned data from simulated FAA sources, such as Low Altitude Authorization and Notification Capability (LAANC) and DroneZone, based on query input(s) obtained via Broadcast Remote ID. The Historical Query returned operation Intent data from USSs. The Network Remote ID Query returned Remote ID data using Network Remote ID as detailed in the ASTM Specification for Remote ID .
- Correlation Query: The Correlation Query focused on the FAA or public safety entities’ need for other FAA-held data (e.g., registration data, airspace authorizations) that correlates to data those entities received via Remote ID broadcast. The Query prototype using the IDIAS component of FIMS and simulated FAA data sources was a success, and potential future investigation, design, and development areas include establishing data exchange requirements for external service provider communications, and the ability of FIMS to receive/verify credentials of the entity submitting a query and return correlation results based on entity’s data access permissions.
- Historical Query: This prototype demonstration and test was also a success. The demonstration aimed to capture latency information for the data exchanges involved in the Historical Query process. Key areas of improvement between the FAA and Industry should focus on applicable use cases, the bounds for historical queries, necessary data and availability, exchange mechanisms, and policy concerns over how historical queries influence data retention and privacy.
Public safety input was gathered via survey data following demonstration activities. Feedback from public safety stakeholders largely indicated that prototype demonstrations were successful, with stakeholders finding much of the provided information from both correlation, and UVR prototypes to be useful.
Recommendations: As prototypes mature, additional participation from public safety stakeholders should continue to ensure end user needs are satisfied.
Off Nominal/Contingent Events
UPP2 Demonstration activities tested off-nominal events for nonconforming and contingent operations, as well as detection and alert of crewed aircraft in the vicinity of the operation using ACAS-sXu. Conformance monitoring was implemented by participating USSs and ACAS-sXu was integrated with a UAS and with an SDSP via a GBRS and a ground-based ADS-B receiver. Each system met the intended goal for the demonstration with nonconforming UA and aircraft being appropriately displayed to stakeholders.
Recommendations: UPP2 conformance, detection, and alert capability demonstrations successfully displayed conformance/non-conformance and alerting as needed. However, test sites noted that the service suppliers may need to improve prototype notifications and response requirements, and adjust timeout allowance from 30 seconds to 120 seconds for returning to conformance. Additionally, better user interfaces could assist with unintentional nonconformance, while additional training may also alleviate unintentional off-nominal events.
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