61ST ANNUAL CONFERENCE, 23-27 May 2022WP No. 83UTM (Unmanned Aircraft System (UAS) Traffic Management)Presented by PLC |
Summary
This paper investigates the relationship between UTM and ATM and the issues created by the simultaneous management of both unmanned and manned traffic. The absence of a complete and comprehensive international regulatory system does not permit a more detailed evaluation of the UTM concept at this stage so the aim of this paper is to provide a general framework to accommodate UTM inside IFATCA environment.
Introduction
1.1. Unmanned Aircraft Systems (UAS) [see note], with their associated technologies, designs, and operating concepts, are evolving rapidly. States are being challenged to safely and efficiently integrate unmanned operations into the highly regulated and well- established manned aircraft environment (ICAO RPAS Concept of Operations (CONOPS)). The Unmanned Aircraft Systems Traffic Management (UTM) is the concept envisaged to be the response to the issue.
1.2. UTM is a highly automated system that aims to manage UAS operations both in controlled and uncontrolled airspace. It will be based on a highly technical and automated environment that will safely and efficiently collect and distribute information among all stakeholders, allowing the UAS operator to be responsible for managing its operations safely without direct interaction with ATM.
1.3. The need to create the UTM derives principally from the volume of operations expected. At the current pace, the number of UAS operations will surpass Conventionally Piloted Aircraft (CPA) operations within a few years and the ATM system’s capacity is unable to accommodate such a demand.
1.4. At this stage of implementation, UTM is considered to be a separate, but potentially complementary, system to the ANSP-managed ATM system. This means the interaction between the two systems may be limited. The implementing process will be progressively moving from accommodation (restrictions and specific requirements to operate) to a complete integration between UAS and CPA and consequently between UTM and ATM.
1.5. The UAS cannot be handled as traditional manned aviation because the type of operations, the technical characteristics, the performances and the absence of the pilot on board make the CPA’s regulation inapplicable in most of the cases. A clear and comprehensive set of UAS/UTM regulations is needed.
1.6. This paper will investigate the interaction between UTM and ATM analysing the problems deriving from the simultaneous management of traffic from the two different systems, UTM and ATM.
Note: Unmanned aircraft system – An aircraft and its associated elements which are operated with no pilot on board. Unmanned aircraft (UA) include a broad spectrum from meteorological balloons that fly freely to highly complex aircraft piloted from remote locations by licensed aviation professionals. The latter are part of the category referred to as “remotely piloted aircraft” or RPA that operate as part of a system, a remotely piloted aircraft system (RPAS). Autonomous aircraft differ from RPAS in that they do not permit intervention of a human pilot to fulfil their intended flight; whereas model aircraft are distinguished by their recreational use. (ICAO Circ. 328)
Discussion
2.1. General consideration on UTM
2.1.1. Definition of UTM
2.1.1.1. ICAO has published “Unmanned Aircraft Systems Traffic Management (UTM) – A Common Framework with Core Principles for Global Harmonization” that defines UTM as:
Unmanned aircraft system traffic management (UTM). A specific aspect of air traffic management which manages UAS operations safely, economically and efficiently through the provision of facilities and a seamless set of services in collaboration with all parties and involving airborne and ground-based functions.
Unmanned aircraft system traffic management (UTM) system. A system that provides UTM through the collaborative integration of humans, information, technology, facilities and services, supported by air, ground or space-based communications, navigation and surveillance.
Note: UTM and UTM System are not reported in any ICAO SARPs: they are used only in the context of the document.
2.1.1.2. ICAO describes UTM as an ecosystem developed by the national Civil Aviation Authorities that includes not only traditional ANSP(s), but also new players called a “UTM Services Provider (USP)”[1], operators and other stakeholders through a distributed network of highly automated systems.
Note: Operator – A person, organization or enterprise engaged in or offering to engage in an aircraft operation. In the context of unmanned aircraft, an aircraft operation includes the unmanned aircraft system. (ICAO DOC10019 RPAS Manual)
2.1.1.3. The services provided have to be identified and detailed by the National Authorities and can be grouped into these categories: Activity Reporting service, AIS, Airspace, Authorization service, Discovery service, Mapping service, Registration service, Restriction Management service, Flight Planning service, Separation service (Strategic and Tactical), Tracking and Location service, Weather service.
2.1.1.4. UTM is considered a separate, but potentially complementary, system to the ATM system. Civil aviation authorities (CAAs) are responsible to ensure the safety and the efficiency of the air operations by issuing regulations and certifying the stakeholders involved. They are also responsible for the harmonization and the oversight of the service provision, both UTM and ATM.
2.1.2. Scope of UTM
2.1.2.1. ICAO states:
ICAO: “Unmanned Aircraft Systems Traffic Management (UTM) – A Common Framework with Core Principles for Global Harmonization” (Edition 3):
UTM is envisioned as a subset of ATM that is aimed at the safe, economical and efficient management of UAS operations through the provision of facilities and a seamless set of services in collaboration with all parties and involving airborne and ground-based functions. Such a system would provide UTM through the collaborative integration of humans, information, technology, facilities and services supported by air, ground and/or space- based communications, navigation and surveillance.
and
ICAO: “Unmanned Aircraft Systems Traffic Management (UTM) – A Common Framework with Core Principles for Global Harmonization” (Edition 3):
Through UTM, it is envisaged that civil aviation authorities (CAAs) and ANSPs, to the extent that they are involved, will be able to make real-time information regarding airspace constraints and flight intents available to UAS operators 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. The primary means of communication and coordination between the ANSP(s), UTM services providers, operators and other stakeholders may be through a distributed network of highly automated systems via application programming interfaces (APIs), and not between pilots and air traffic controllers via voice communication.
2.1.2.2. According to the general concept, UTM has to manage/authorize only unmanned operations both in controlled and uncontrolled airspace and the services will be provided only to UAS. Nevertheless, to ensure the safety of the operations and avoid any overlap of conflicting or incompatible services or areas of responsibility, ANSPs and manned aviation will participate in sharing information through UTM.
2.1.2.3. On the other hand, not all the UAS have to be managed by UTM: those that meet the requirements and minimum performances established by the national CAA (usually known as Certified Category) can also be handled similar to manned aviation by ATM.
2.1.3. Implementation
2.1.3.1. To harmonise UTM implementation, ICAO has specified four main requirements for UAS-ATM integration [2]:
- The integration of UAS shall not result in a significant impact on current airspace users;
- UAS shall comply with the existing and future regulations and procedures laid out for manned aviation;
- UAS integration shall not compromise existing aviation safety levels nor increase risk more than an equivalent increase in manned aviation would;
- UAS operations shall be conducted in the same way as those of manned aircraft and shall be seen as equivalent by ATC and other airspace users.
2.1.3.2. The UTM concept is quite recent (7ICAO has formalized the concept in 2016) and therefore not fully developed: at international level, only a few items have been incorporated in the Annexes (mainly definitions). The economic pressure behind the UAS market has pushed States to implement partial regulation to allow the operations (including a Concept of Operations or ConOps) but without the harmonised approach favoured by ICAO.
2.1.3.3. At time the time of writing, the general concept is “accommodation”. That is, UAS can operate along with some level of adaptation or support that compensates for its inability to comply within existing operational constructs (for example dedicated corridors/areas, increased spacing around the manned aircraft). The final step will be the “integration” of unmanned operations (estimated from 2025/30) where UAS may be expected to enter the airspace system routinely without requiring special provisions. Integration will require the implementation of harmonized Standards and Recommended Practices (SARPs) and procedures (PANS) [3].
2.1.3.4. The current core business is located in the Very Low Level airspace (VLL) [see note] and the main drivers are the Urban Air Mobility (UAM), parcel delivery and agricultural uses. For this reason, most of the ConOps developed are focused on this and rarely consider the interaction with ATM or with manned aviation. Operations in Very High Level airspace (VHL) is also starting to be considered but the number is very low and almost no documents are available.
Note: VLL is defined as the airspace below the minimum height used by manned VFR aviation (ICAO Annex 2 “Rules of the Air”, 4.6): Except when necessary for take-off or landing, or except by permission from the appropriate authority, a VFR flight shall not be flown: over the congested areas of cities, towns or settlements or over an open-air assembly of persons at a height less than 300 m (1 000 ft) above the highest obstacle within a radius of 600 m from the aircraft; b) elsewhere than as specified in 4.6 a), at a height less than 150 m (500 ft) above the ground or water.
2.2. Interaction UTM-ATM
2.2.1. As reported above, currently it is the national CAAs that have to develop regulations that integrate the UTM in the current aeronautical system including the responsibilities, interface, services, the airspace inside which the services will be provided and the minimum requirements to enter the airspace. Contingency procedures and the interaction between UTM and ATM also have to be developed.
2.2.2. Avoiding considering segregation, that by its intrinsic nature solves the problem of the interaction, the situation can result in heterogeneous traffic provided with different services from different providers in the same portion of airspace. From this (potentially hazardous) perspective derives the need to clearly identify and confirm the roles of UTM and ATM related to airspace and traffic management responsibilities and functions.
2.2.3. The essential element is to identify the applicable delineation between ATM and UTM, thus what ICAO defines “boundary”:
ICAO: “Unmanned Aircraft Systems Traffic Management (UTM) – A Common Framework with Core Principles for Global Harmonization” (Edition 3):
The UTM-ATM boundary should be understood as any physical boundary, or a combination of boundaries, as set by airspace design, a service boundary defined by distinct sets of services provided by an ANSP and USP, and/or a system boundary defined by the technical CNS/ATM system.
2.2.4. Once the boundaries are defined, responsibilities deriving from the provision of the services shall be clearly identified. In addition, airspace users have to be aware of which kind of services are being provided and regulations apply. Due to the technical constraints and limitations of different provider architectures, the information or separation provided will differ according to the relevant service and regulation.
2.2.5. The safe separation of aircraft is a responsibility of the ATM service providers. But if the manned operations are conducted close to the boundary, separation standards between manned and unmanned traffic may have to be developed [see note]. This process has to take into account that the current sets of flight rules (VFR and IFR) and the current airspace classification (with the related services) are not sufficient to accommodate UAS. Furthermore, the general concept of the responsibility of the UAS Operator of avoiding collision with manned aviation has to be considered.
Note: Separation Assurance – the design and application of airspace and procedures that actively maintain the appropriate and predefined margins of separation around, above and below each aircraft. (IFATCA, Toulouse 1998, WP84 “Airborne Separation Assurance”)
2.2.6. The next step is to establish how these boundaries can be crossed. Interoperability is a key requirement for ATM-UTM interface and, even if the general definition of ATM [see note] can be easily adapted to UTM, the systems have substantial operational and structural differences: the ATM system can be considered a ‘human centric’ system whereas UTM is envisioned as digitally based.
Note: Air traffic management system. A system that provides ATM through the collaborative integration of humans, information, technology, facilities and services, supported by air and ground- and/or space-based communications, navigation and surveillance. (PANS-ATM)
2.2.7. This different approach requires a deep analysis of the human factors aspects related to the exchange of information between the two systems. The WP “Display of Unmanned Aerial System (UAS) surveillance data on Controller working position” (presented by PLC and TOC during the 57th annual conference, Accra, Ghana) can provide some guidance:
IFATCA 57th annual conference, Accra Ghana, March 19-23, 2018, Agenda item B:5.6/C.6.1, WP No. 90, Display of Unmanned Aerial System (UAS) surveillance data on Controller working position, Section 3. Conclusions:
3.1. Consideration of the practicality, sensibility, and most importantly, the safety of the system will be required prior to implementation of integration of UAS data into ATM’s.
3.2. Only when the systems are capable of doing so without negatively affecting the primary and existing function of the ATM or the priorities and workload of the controller, IFATCA encourages Regulators, ANSP’s, suppliers and users to consider integration of UAS data into ATM systems.
3.3. Until this is possible, IFATCA believes the current method of allowing UAS use in controlled airspace, by way of segregation from, and in some circumstances exclusion from, areas around aerodromes and other sensitive airspace, is the safest, and most prudent or acceptable method of facilitating this rapidly evolving technology.
3.4. Controllers must be central to, and included in, any planning, design or creation of systems to facilitate the inclusion of surveillance information from UAS on controller working positions or changes to operating practices in relation to this.
3.5. IFATCA recommends ANSP and Regulators include training and education of all airspace users, including Controllers, in the application and use of any regulation, policy and procedure, or equipment changes that may occur as a result of integrating UAS into the existing aviation framework.
2.3. Possible scenario
2.3.1. A possible scenario is a defined portion of airspace where an ATS Unit is entitled to provide ATS to CPA and, within the same portion of airspace, UTM is responsible to manage unmanned aircraft.
2.3.2. In case of conflict, as reported in the scope of UTM (para. 2.1.2.1), the unmanned operator will contribute in solving the conflict. Using the UTM system capabilities, it will use the services provided and the necessary technical equipment, for example a Detect And Avoid system (DAA), to ensure the safety of the operation. Despite the UTM, the responsibility of the CPA pilot to avoid collisions through a visual observation remains unchanged (General Flight Rules).
2.3.3. From the ATC perspective, the ATCO/FISO has to apply the different relevant regulations according to the kind of traffic involved (manned-manned or manned- unmanned). This can be seen as mixed mode operations and IFATCA has policy on this topic.
| IFATCA TPM (2019) – 2.3.3.1. ATS 3.13 MIXED MODE OPERATIONS, p. 111:
Mixed mode operations are defined as ATM Operations that require different procedures due to variances in airspace users’ characteristics and/or ATM design within the same area of controller responsibility. Efforts should be undertaken to reduce existing Mixed Mode Operations by creating intrinsically safe solutions. Introductions of new Mixed Mode Operations should be avoided by creating intrinsically safe solutions. When safety of a Mixed Mode Operation cannot be completely managed at an intrinsic level, assessment must take place that the change in the ATM system does not increase controller workload to an unacceptable level. |
2.3.4. A fundamental aspect that has to be highlighted is that the separation is established only if all the actors involved are provided with the necessary information to take the appropriate actions. This confirm, once again, that the exchange of information to build a shared and common situational awareness is essential for the safety of the operations.
2.3.5. A possible solution, as reported in some ConOps, is that CPAs are required to “join” UTM if they want to fly through airspaces where UTM is provided. From the ATC point of view, this procedure can be sustainable only with an adequate regulatory framework that details tasks and responsibilities to avoid unsafe situations where an aircraft is provided with different or, in the worst-case scenario, conflicting information or instructions.
2.4. Future considerations
2.4.1. As stated in this paper, most of the regulation and requirements used for manned aviation are not applicable to UAS (except from RPAS). Flight rules, airspace classification, performance and CNS capabilities, responsibilities are some of the aspects that need to be investigated in the near future.
2.4.2. From these considerations, some questions need an answer to allow the accommodation and subsequently the integration of UAS inside the current airspace structure:
- Which are the characteristics of an ATM-UTM boundary?
- Which are the requirements for the ATM-UTM interface?
- Which information have to be exchanged between the systems?
- Is a direct communication link between remote pilot and ATC necessary?
- Is a new class of airspace necessary to identify those portions of airspace where ATM and UTM are both provided or the current classification could be adapted?
Conclusions
3.1. The UTM system is distinct, but complementary to, the ATM system, and provides for the safe management of unmanned operations inside both controlled and uncontrolled airspace.
3.2. The system is based on a set of highly automated services and it shares the global airspace situation updated by all the stakeholders involved (ANSPs, operators, USPs and others). The UAS operator would be able to acquire the correct situational awareness and will be responsible for managing its operations safely.
3.3. Interoperability is a key requirement for ATM-UTM interface and the exchange of all the necessary information is fundamental for the operations. Clearly defined boundaries between the two systems and related regulations allow ATCOs to safely manage their traffic.
3.4. The necessary regulations for the interaction between UTM and ATM have not been developed yet at international level. Most States have adopted their own approach to the matter creating a fragmented environment without setting up and solving the interaction issue.
3.5. IFATCA supports a phased approach to integrate ATM and UTM. For the consideration made in the discussion part, segregation is envisaged as the safer solution applicable at the current stage of implementation. The integration phase will be possible only with a regulation that takes into account the technical and organizational characteristics of the two systems.
Recommendations
4.1. It is recommended that the following definitions are adopted and added to the IFATCA TPM, PART II – ACRONYMS AND TERMS:
Unmanned aircraft system traffic management (UTM). A specific aspect of air traffic management which manages UAS operations safely, economically and efficiently through the provision of facilities and a seamless set of services in collaboration with all parties and involving airborne and ground-based functions.
Unmanned aircraft system traffic management (UTM) system. A system that provides UTM through the collaborative integration of humans, information, technology, facilities and services, supported by air, ground or space-based communications, navigation and surveillance.
Separation Assurance. The design and application of airspace and procedures that actively maintain the appropriate separation minima between aircraft.
4.2. It is recommended that the following policy is adopted and added to the IFATCA TPM – [NEW HEADING] AAS 1.XX UNMANNED AIRCRAFT SYSTEM (UAS) TRAFFIC MANAGEMENT (UTM):
The roles of ATM and UTM related to traffic management shall be clearly identified.
The UTM-ATM boundary shall allow an unambiguous identification of responsibilities and functions of the two systems.
The interface between the ATM and UTM shall guarantee the exchange of the necessary information for the safe management of the traffic.
Comprehensive regulatory framework and procedures for the ATM-UTM interaction shall be established before implementation.
References
[1] ICAO: “Unmanned Aircraft Systems Traffic Management (UTM) – A Common Framework with Core Principles for Global Harmonization” (Edition 3). [2] EUROCONTROL UAS ATM CONOPS and ICAO Cir 328.IFATCA TPM 2019.
IFATCA, Toulouse 1998, WP 84 “Airborne Separation Assurance”.
IFATCA, Santiago 1999, WP 154 “Transfer of Separation Functions to Pilots – Human Factors Aspects”.
IFATCA, Hong Kong 2004, WP 158 “Co-opertive separation”; IFATCA, Toronto 2017,WP 156 “ATCO duty of Care”.
IFATCA, Accra 2018, WP 90 “Display of Unmanned Aerial System (UAS) surveillance data on Controller working position”.
ICAO Annex 2 – Rules of the Air (ICAO, tenth edition, July 2005).
ICAO Annex 11 – Air Traffic Services (ICAO, fifteenth edition, July 2018).
ICAO DOC 10019 – Manual on Remotely Piloted Aircraft Systems (RPAS) (ICAO, first edition, 2015).
ICAO DOC 4444 – PANS-ATM (ICAO, sixteenth edition, 2016).
ICAO DOC 7300 – Convention on International Civil Aviation (ICAO, 7300/9 ninth edition, 2006).
ICAO Cir 328 – Unmanned Aircraft Systems (UAS).
REMOTELY PILOTED AIRCRAFT SYSTEM (RPAS) CONCEPT OF OPERATIONS (CONOPS) FOR INTERNATIONAL IFR OPERATIONS (ICAO).
Unmanned Aircraft Systems Traffic Management (UTM) – A Common Framework with Core Principles for Global Harmonization” (ICAO, Edition 3).
UAS ATM Integration, Operational Concepts (Eurocontrol, 2018); CORUS: Concept of Operations for U-space (SESAR, 2019).
Unmanned Aircraft System (UAS) Traffic Management (UTM): Concept of Operation v1.0 (NextGEN, May 2018).
Unmanned Aerial Systems (UAS) Traffic Management: Safe and efficient UAS operations (NASA).
Blueprint for the sky: The roadmap for the safe integration of autonomous aircraft (AIRBUS).
FAA, UAS Data Exchange (Low Altitude Authorization and Notification Capability (LAANC))” https://www.faa.gov/uas/programs_partnerships/data_exchange/
ICAO UAS TOOLKIT
https://www.icao.int/safety/UA/UASToolkit/Pages/default.aspx
Last Update: August 2, 2022