<p>Continuous descent at idle thrust in a clean configuration is considered the most efficient descent path for commercial aircraft. The airspace structure, in which all airspace participants move, has to allow this. The advent of a more modern generation of aircraft with more efficient descent characteristics may have led to outdated airspace design rules as they may have not been adjusted concurrently with aircraft development. This paper evaluates the compatibility of current airspace design guidelines with the descent behavior of a modern commercial aircraft. Specifically, the paper focuses on Airbus A350-900 aircraft during their approach and descent phase at Munich airport in the 2022/2023 winter flight schedule to provide an overview of the descent characteristics of a newer aerodynamically efficient low-drag aircraft at a highly frequented German airport. The real flown and theoretically possible gradients within the airspace structure around Munich airport are calculated and evaluated based on real-time flight tracking data. It is checked whether flights have entered unprotected dimensions of the airspace system around the airport. In the controlled airspace around Munich airport, flight routes exist that exceed the assumed most efficient descent gradient in clean configuration at the speed with the maximum lift-to-drag coefficient of the Airbus A350-900 due to the airspace dimensioning. Among these flight routes, there is an increased proportion within unprotected class E airspace. A proposal is made to improve the situation in the identified airspace areas by introducing temporary controlled airspaces or airspaces in which all participants are known to air traffic control.</p>