Higher Airspace Traffic Management (HATM)
Higher Airspace Operations
Higher airspace operations (HAO) refer to those that take place above the majority of today’s general air passenger traffic, which is notionally above Flight Level 500. Operations have historically been limited at these altitudes due to the challenges conventional fixed wing aircraft face in reduced atmospheric density of the upper stratosphere and mesosphere. They have typically been conducted only by military aircraft or research aircraft on specific missions.
Recent advances in technologies, however, relating to power and propulsion, aircraft structures, flight automation, and aerodynamics have led to an increase in the number and types of aircraft that can operate in low atmospheric density airspace. New aircraft designed to operate at high altitudes, depicted in Figure 1, have proved to be attractive investments to commercial entities. Sophisticated unmanned free balloons, long endurance High Altitude Platform Stations (HAPS), remotely piloted aircraft systems, supersonic transport (SST) aircraft, and hypersonic aircraft comprise the fleet of future higher airspace operators. These aircraft will provide a range of services including telecommunications, scientific research, technology testing, environmental monitoring, disaster management, high speed passenger transport, and more. Demand for these types of services will likely continue to grow with the advent of new technologies and business markets.
Figure 1: Higher Space Vehicles
The Need for HATM
The increase in demand for HAO presents some challenges for the provision of airspace management services. First, aircraft that operate in higher airspace have vastly different performance characteristics and operational profiles than aircraft operating in the lower altitude strata, and many have high levels of automation. Second, existing supporting infrastructure for airspace management becomes more limited as altitude increases. Lastly, airspace regulations and air traffic services in higher airspace vary by country/State, yet HAO can and will span countries across the globe.
Higher Airspace Traffic Management Vision
To address the challenges associated with future higher airspace demand, the FAA, in collaboration with NASA and industry, is exploring and maturing a concept called Higher Airspace Traffic Management (HATM), formerly known as Upper Classe E Traffic Management (ETM), that modernizes approaches and supporting capabilities for managing aircraft at high altitudes. HATM is a cooperative traffic management concept that provides a means for air traffic management (ATM) to manage the airspace more flexibly and efficiently through the authorized use of Cooperative Areas (CAs), on an as needed basis, within which operators take responsibility for the management of their operations, under the FAA’s regulatory authority, while ATC maintains its traditional responsibilities outside these areas.
With HATM, higher airspace operators, and most notably those that loiter or operate persistently, often within fleets of aircraft, provide their own conflict management within CAs, as they are best suited to synchronize their operations with those of others. They share information with each other in a highly automated, information-rich environment that promotes shared situational awareness about each other’s operational intent (OI), or an operator’s intended/predicted position over a future time horizon, and status. They can use alternative, performance-based Communications, Navigation, and Surveillance (CNS) and conflict management capabilities that best suit their operations to manage traffic within CAs, provided a standard CNS performance and FAA-approved operator-to-operator practices are employed. A digital information architecture provides seamless access to accurate and timely information across the federated network of stakeholders.
HATM is an airspace management option that does not require large investments. Services are tailored to the environment using new data-centric technologies that will link diverse entities, including operators, data and technology service providers, and automated systems. Airspace operations within CAs are able to be seamlessly integrated into the existing ATM system, with established rules, procedures, and standardized information exchange protocols to support interactions with ATM and other stakeholders as needed. Higher airspace operators execute missions and meet business objectives safely and efficiently within the CAs through continuous sharing of OI and cooperative deconfliction. ATM authorizes and has awareness of the operations but does not have to take on the computational and human workload associated with providing separation services.
Figure 2: HATM airspace management model
The HATM Concept of Operations v2.0* (December 2025) is accessible via the provided link: HATM ConOps
* HATM ConOps v2.0 supersedes ETM ConOps v1.0
Higher Airspace Communication, Navigation, and Surveillance (CNS) White Papers
The FAA has published a series of white papers that identify and analyze emerging and/or existing Communication, Navigation, and Surveillance (CNS) capabilities applicable to the HATM environment. The documents assess various CNS technologies and examine some of the advantages, disadvantages, current level of support, and potential modifications for increased HATM operations support. The white papers are intended to provide options that may support Operators in HATM airspace, rather than prescribe any one solution. The papers are linked below under "Reference Documents."
Contact
For additional information regarding HATM, please send an email to matt.modderno@faa.gov.
Reference Documents
- HATM Concept of Operations v2.0 (PDF)
- HATM Communication, Navigation, and Surveillance (CNS) Summary Report (PDF)
- Existing Communication Technologies for ETM (PDF)
- Existing Navigation Technologies for ETM (PDF)
- Existing Surveillance Technologies for ETM (PDF)