FAQ n.142994

There is no internationally agreed legal boundary defining the vertical limit of national airspace or the start of outer space. However, commonly used conventions include:

• Airspace: Generally considered to extend up to the altitude where aerodynamic flight is no longer practicable, typically below 80–100 km above mean sea level.
• Outer space: Commonly referenced as beginning at the Kármán line (100 km). Some States use an alternative operational reference of 80 km.

These references are based on established practice and common understanding, rather than on formal legal definitions, and are used to support operational coordination and safety management.