Flying high: Comparing the concepts for higher airspace operations in the U.S. and Europe

Higher airspace, 60,000 feet and above, was once the exclusive domain of stratospheric balloons and high- performance military aircraft. Traditional operations are limited to the capacity of conventional fixed-wing aircraft at reduced atmospheric density. But new technologies are leading to a growing number of vehicles that can operate in such conditions. There is a wide range of technological solutions and operational applications leading to various forms and types of vehicles, from balloons, airships, and sophisticated long-range aircraft to novel supersonic/hypersonic aircraft or suborbital spacecraft. New operational concepts are emerging that were not envisioned even a decade ago. Operational trials have demonstrated solar aircraft remaining airborne for months at time, forcing us to rethink the way airspace can be used. As new aircraft types emerge, new opportunities are created to deliver services from the stratosphere. On both sides of the Atlantic, concepts are being developed to accommodate the expected increasing use of higher airspace. New vehicle concepts go hand in hand with emerging markets and evolving demand conditions. Traditional air traffic management must adapt to the specific requirements of these utilization concepts in order to efficiently combine their operation with existing air traffic and expand the opportunities the stratosphere provides. The basic subject matter is identical in the U.S. and in Europe, but there are differences in the operational constraints and in the expected usage demand. This is reflected in the approaches chosen to integrate higher airspace operations into airspace. The paper compares the developed operational concepts with each other and shows differences but also synergetic effects. In particular, questions of interoperability and the resulting requirements for operational implementation are considered.