ICAO’s UTM Common Framework study edition three highlights gaps, issues and challenges

Edition three of the International Civil Aviation Organization’s (ICAO’s) UAS traffic management “Common Framework with Core Principles for Global Harmonization”, widely made available earlier today by ICAO, identifies the key gaps, issues and challenges facing States in their work to develop a national UTM system.  The third edition adds new information gathered from the submissions to ICAO’s 2017, 2018 and 2019 Requests for Information (RFI) and material provided during the respective ICAO DRONE ENABLE Symposia. It is intended to provide a framework and core capabilities of a “typical” UTM system to States. “A common framework is needed to facilitate the harmonization between UTM systems globally and provide a stepped approach towards integration into the ATM system,” says the report.

“Through UTM, it is envisaged that civil aviation authorities (CAAs) and ANSPs (air navigation service providers), to the extent that they are involved, will be able to provide real-time information regarding airspace constraints and the intentions of other aircraft available to UAS operators and their remote pilots directly or through a UTM service provider (USP). The UAS operator would then be responsible for managing its operations safely within these constraints, without receiving positive air traffic control (ATC) services from the ANSP.”

In the “Gaps, issues and challenges” section of the study the text states:

The safe and efficient integration of UAS, particularly small UA, into existing controlled and uncontrolled airspace presents a variety of issues and novel challenges. Recent studies forecast significant growth of UAS operations, leading to a shift of focus to operations in the low-level environment and above populated areas, with various types of operations and UA.

This will likely include:

  • operations at altitudes in the very low-level structure (e.g. below 150 metres or 500 feet above ground level (AGL));
  • systems with high levels of automation and connectivity;
  • greater number of operations, which raises questions about the sustainability and scalability of a UTM system and the ability of ATM infrastructure to accommodate these new users;
  • flights not conducted in accordance with IFR or visual flight rules (VFR) with the potential of establishing UAS-specific flight rules; and
  • reliance on data links (either non-traditional ground-based links, C2 Links or data links associated with UTM systems), raising new challenges related to frequency spectrum, resilience and cybersecurity.


Many of the gaps addressed below become more significant at the boundaries between UTM and ATM systems and/or when UA transition between these systems.

  • Airspace classification. The current airspace classification scheme as developed for manned aviation may not effectively support visual line-of-sight (VLOS) or BVLOS operations. This gap includes the potential modification of current classes of airspace or potentially creating new classes of airspace to accommodate the range of needs brought by UAS operations.
  • Airspace access. The policies, rules and priorities required to support equitable access to airspace must be developed (the European Union, for example, is examining policies on fair access to airspace).
  • Rules of the Air. Rules of the Air which specify flight rules, right-of-way, altitude above people and obstructions, distance from obstacles and types of flight rules, all of which, as written, are incompatible with the intended operations within UTM systems.
  • Operational procedures. Procedures specific to the UTM system, including normal, contingency and emergency scenarios, are needed. Such procedures would need to be harmonized with ATM systems whenever UAS operations are planned near the boundary between UTM and ATM or if UA will transit from one system to the other.
  • Liability. Liability and insurance implications for USPs in relation to UAS operators must be determined.
  • Certification. Certification of the UTM system, particularly when interacting with an ATM system, and, for UA, meeting the principles of airworthiness, scaled to an appropriate level based on risk(s).
  • Data standards. Appropriate data standards (e.g. data quality specifications, data protection requirements) and protocols to support UTM safety-related services and the exchange of data between UTM and ATM systems as well as between multiple UTM systems are needed.
  • Positional references. Common altitude, navigation and temporal references for manned and unmanned operations are needed. Gaps in the use of reference points and equipment providing different levels of accuracy and performance in the measurement of altitude, navigation or time introduce safety concerns which must be resolved. Determining the extent to which traditional aviation standards can be used remains a work in progress. Traditional standards which address the provision of such references should be utilized whenever possible.
  • Interface between UTM and ATM. There is a need to develop procedures and adequate tools to ensure the sharing of information, the interoperability of the two systems, and to identify roles, responsibilities and limitations.
  • Data recording. Data-recording policies and capabilities, similar to ATC data retention and aircraft flight recorder requirements, are needed to support accident/incident reporting and investigative requirements.
  • Communications. Remote pilot interfaces as well as capabilities and performance requirements for communications with the UTM system must be developed. These include the ability to interface/communicate with ATC and pilots of manned aircraft.
  • Alerting systems. The safety and integrity of the UTM system, failure-alerting and failure management must be addressed. Policies, guidance and procedures will need to be developed to address the degradation or failure of the various UTM components or entire UTM system as well as the restoration of systems after such degradations or failures.
  • Contingency management protocols. A dynamic operating environment must have operating protocols that account for contingencies both of the UTM system(s) providing multiple services and of the aircraft operating within the UTM system.


The issue of modification, adaptation or applicability of requirements for airspace and procedure design when considering topics such as navigation performance has yet to be addressed. To ensure system reliability and safety, frequency spectrum availability and supportability need to be determined based on the UTM system architecture. The establishment of a UTM service within a volume of airspace may affect the classification of that airspace (e.g. changes from Class G to D airspace). The UTM and ATM interface, including responsibilities and procedural development, must be addressed to ensure compatibility between manned and unmanned operations. UTM and ATM systems may have different communications, navigation and surveillance (CNS) requirements for different aircraft. The systems need to exchange data effectively so that each system can manage the aircraft relevant to its responsibilities. CNS requirements in UTM may differ from ATM. Data sharing protocols will need to consider State data privacy policies. Further research is required to support the development of the interoperable standards and protocols for the elements of UTM and ATM data exchange.


Aircraft participating in the UTM system must be separated from each other and from other hazards (e.g. buildings, terrain or adverse weather). This separation management should include guidance and responsibilities complemented by other tools and procedures to properly address scalability. Separation management may have to be supported by additional standards, policies, capabilities or tools, including:

  • a DAA capability to identify/detect and avoid conflicting aircraft and any other hazards;
  • methodologies to allow improved or enhanced detectability and conspicuity of UA by manned aviation;
  • assignment of responsibility for conflict management and separation provision, particularly in low-level airspace, which may include unique solutions such as separation provision being delegated to the UA or the UTM system;
  • development of UA separation standards within the UTM system, which may include the need for safety margins based on elements such as airspeed, weight and UA equipment;
  • assessment of existing and future separation standards between UA and manned aircraft whenever they operate in proximity to each other;
  • determination of the relevant surveillance capability and performance for the UTM system to support the integration of new or novel aircraft and operations;
  • development of policies to address means of compliance or system approval for UTM systems; · implementation and maintenance of a safety management system as currently required by aviation systems related to manned aviation; and
  • achievement of a required data quality (e.g. on accuracy, resolution, integrity, timeliness, completeness, traceability, format) of the system. The standards applied to UTM systems that are intended to interface with the ATM system will need to be compatible and interoperable.
  • forecasting and dissemination of micro-weather to address localized weather patterns that may impact low altitude UA operations (e.g. urban canyon phenomenon, windshear, diurnal effects caused by urban structures, etc.).


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