International standards agency ASTM International has published a new international standard, ASTM F3548-21, relating to Uncrewed Traffic Management (UTM) UAS Service Supplier (USS) interoperability. F3548 is intended to be a global specification providing components that may be used to satisfy requirements expected to be common to many UTM-related regulations. The flight operations subcommittee of ASTM’s unmanned aircraft committee (F38) developed the new standard on UAS traffic management (UTM) with input garnered across multiple continents and a diverse group of industry contributors.
It is focused on strategic aspects of UAS operations, including strategic conflict detection, aggregate conformance of operations to their operational intents, constraint awareness, and situational awareness in the event of nonconforming or contingent operations. The intention is that this specification will evolve to address increasingly complex strategic aspects of UAS operations and potentially certain tactical aspects of UAS operations.
F3548 addresses the performance and interoperability requirements, including associated application programming interfaces (APIs), for a set of UTM roles performed by UAS Service Suppliers (USSs) in support of UAS operations.2 Roles are groupings of one or more related UTM services. A competent authority may choose to use the roles defined in this specification in establishing the granularity of authorizations granted to a USS. The roles defined in this specification are:
(1) Strategic Coordination, comprising the Strategic Conflict Detection and Aggregate Operational Intent Conformance Monitoring services;
(2) Conformance Monitoring for Situational Awareness (CMSA);
(3) Constraint Management, comprising the Constraint Management service; and
(4) Constraint Processing, comprising the Constraint Processing service.
The Conceptual Overview provides a description of each of the services and roles and includes further discussion on their scope.
In a region where participating UAS operators voluntarily agree to or are required by the competent authority to comply with this specification, it enables strategically deconflicted UAS operations as well as situational awareness for operations that may not be required to be strategically deconflicted. This specification is not dependent upon the use of segregated or non segregated airspace.
It applies to operations conducted in a connected environment, meaning the UAS personnel have access to the USS (typically by means of the internet) and connectivity to the Unmanned Aircraft (UA). This specification anticipates and accommodates limited gaps in connectivity, but does not purport to address operations in locations where persistent connectivity is unavailable.
A regulator may choose to require that a USS support a minimum or prescribed set of roles and services and may adopt terminology other than USS for a software system that provides something other than that minimum or prescribed set of roles and services. However, for purposes of this specification, a USS is a system that provides one or more of the UTM services defined in this specification.
A USS is not required by this specification to perform all roles or implement all defined services, providing business case flexibility for implementers. A typical USS that supports operators in the planning and execution of UAS operations may implement the Strategic Coordination, Constraint Processing, and CMSA roles. (Note that a USS providing CMSA for a UAS operation is required to also provide Strategic Coordination for the operation.) However, other implementations more limited in scope are possible. For example, a USS may implement only the Constraint Management role and be intended for use only by authorized constraint providers; or, a USS may implement only the Constraint Processing role to provide general airspace awareness to users independent of planning UAS flights. USSs may also provide additional, value-added capabilities and still be compliant with this specification as long as the value-added capabilities do not conflict with the services defined in this specification, and the implementation of services defined in this specification conforms to the applicable requirements.
A USS may also support other UTM roles such as Remote ID and airspace access (for example, the FAA’s LAANC), specified in other documents.
F3548 addresses aspects common to all roles and services, such as Discovery and Synchronization Services (DSS), security, auditing, and handling of off-nominal cases (for example, USS or DSS failures).
Additional services or enhancements to the current services will be added to subsequent versions of this specification. Appendix X2, Future Work Items, identifies a set of these items.
The safety case for this version of the specification, summarized in Appendix X4, is limited to strategic deconfliction, which is accomplished using the services provided by the Strategic Coordination role. This analysis does not constitute a full safety case for any particular operator or set of operations, which will have their own unique factors and variables. It does help operators understand, however, the contribution of using strategic deconfliction to their safety case and what the key variables are in increasing or decreasing the contribution. Using assumptions similar to those documented in Appendix X4, strategic deconfliction reduces the probability of midair collisions by approximately two to three orders of magnitude, with the rate of off-nominal events and participation being the key variables.
(Image: ASTM, Getty)
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