On The Radar
Just like uncrewed aircraft systems (UAS, aka drones), eVTOL aircraft require access to low-altitude airspace in and around cities to operate productively. They also need to fly in existing controlled airspace alongside larger aircraft, especially in close proximity to airports.
Many technology specialists are intently focused on how these requirements can be met safely, but the envisaged new approach to so-called uncrewed traffic management (UTM) also raises important questions about market access and equitable use of public resources, including airspace and landing sites.
This is a challenge that Airbus Unmanned Traffic Management has been addressing for some time as part of the Airbus Cubed innovation unit. The California-based subsidiary of the European aerospace group, which is itself developing an eVTOL called CityAirbus NextGen, recently partnered with the Massachusetts Institute of Technology (MIT) to develop a "Fairness Engine" for managing equitable and workable access to airspace. The partners have published a paper to explain what it has in mind.
In simple terms, the Fairness Engine is an attempt to bring a degree of objectivity that could too easily descend into subjectivity. Traditional air traffic management is generally handled on a first-come, first-served basis, but Airbus UTM believes that a different approach is needed to avoid inequity and added costs as new types of aircraft enter the mix. One key consideration is that many new applications for eVTOLs and drones could be that they are unable to file early flight plans due to the ad hoc nature of their operations.
"Fairness is subjective but can be encoded into a set of prioritization rules based on input from an authority, airspace users, and the community," Scot Campbell, U.S. head of Airbus UTM, told FutureFlight. "The set of prioritization rules will likely be different between different areas of the world based on how the notion of fairness is interpreted."
The Airbus/MIT response is to seek to determine priorities for airspace access on the purpose of the flight so that, for instance, an emergency medical mission might take priority over a passenger or freight delivery flight. Where this isn’t a distinguishing factor, the Fairness Engine would apply other metrics, agreed by users, to establish structures for prioritizing flights.
"The first step is to standardize the data that are necessary to monitor airspace fairness, such as the ratio of operation denials to operation requests, as well as to define goals for airspace access, such as whether on-demand and scheduled operations should have equal access," Campbell explained. "The second step is to monitor the operational data to identify instances of unfair airspace access. Finally, fairness controls, such as prioritization, can be implemented in response to observed instances of unfair access."
According to Campbell, establishing “fairness” principles in UTM needs to be done as soon as possible to ensure the new mode of air mobility gets off to the best possible start. Among other considerations, the engine might consider the relative cost of traffic management for each operator. The company said is already trialing the approach in at least one, undisclosed, UTM system now in development.
In Europe, the CORUS-XUAM project has been concentrating on how to deliver equitable access to airspace and other infrastructure for new types of aircraft.