Equipped with accurate flight information, the mythical Greek figure Icarus could have avoided flying too close to the sun, a path that caused his wings to melt and sent him tumbling into the sea. SESAR’s integrated common altitude reference system for U-space (ICARUS) exploratory research project protects against such mishaps by ensuring manned and unmanned airspace users access the same altitude reference system.
Airspace users need to know their height to avoid obstacles and to maintain safe vertical separation with other users. This is especially important in low-level airspace where growing numbers of unmanned aerial systems share the airspace with traditional aviation, rotorcraft, gliders and balloons. “Traditional aviation relies on barometric pressure to determine altitude, whereas small drones use satellite signals to navigate and measure height. Not only are the two systems incompatible, but barometric measurements are less accurate in urban environments or near ground obstacles,” explains Alberto Mennella, Innovation Manager and founder of drone technology company TopView – the company that led ICARUS validation activities. Alberto Mennella helped solve the problems and limitations imposed by both barometric and geodetic height estimation models by working with other ICARUS partners to develop a collection of services that enable all users to continue to use their preferred altitude reference system while ensuring safety and interoperability.
“We defined a prototype and validated this concept through the definition of three linked services,” explains Alberto Mennella. “The vertical conversion service performs the barometric-geometric conversion; the real-time geospatial information service provides a digital model of the terrain; and the vertical alert service warns of obstacles that might impact the flight trajectory.” The concept was tested using five relevant use cases involving general aviation pilots and unmanned aircraft to guide the design of the micro-service architecture. Preliminary simulations in Polish airspace were followed by flight trials in an intensive validation campaign in Italy in 2021. The results showed how pilots can use ICARUS services in strategic and tactical phases of flight to access altitude translation, terrain profiles and known obstacles, to support beyond visual line of sight operations in shared airspace.
The ICARUS prototype has achieved very high-level results that has led to a preliminary concept of operations for three U-space services. The new U3 altitude translation services mark the first step in creating a common altitude reference system necessary to enable drone operations at scale. It will provide drone operators and aviators with a common altitude reference as well as accurately measure distance from the ground and known obstacles. The new services are now part of the draft ISO DIS 23629-12 requirements for U-space service providers published in July 2022 to support industry standardisation. “The concept is there, and the data has been published online,” says Alberto Mennella. “Now we need to industrialise the service and develop documentation and certification to support real-time services.”