B. Joseph Krabacher and Milton “Skip” Smith

Recent events surrounding Chinese “surveillance/weather/stratospheric” balloons observed over the continental United States and Latin America raise questions regarding the limitations on airspace and outer space. Air law governs the territorial airspace and national sovereignty in each nation’s airspace, and space law governs the law of outer space.

Under international law, the airspace above a national territory (including its territorial waters) belongs to the national government controlling the territory but does not include “outer space.” Where airspace ends and outer space begins has never been clearly defined. Nevertheless, the law governing airspace sharply contrasts with the law governing outer space.

There have been debates over the years as to where airspace ends and outer space begins. The von Kármán line, which seeks to define the imaginary boundary between outer space and the atmosphere of the Earth, is defined by the Fédération Aéronautique Internationale (FCI) as beginning at 100 km (330,000 feet), where the atmosphere is typically considered to be insufficient to provide adequate lift for conventional aircraft flight. FCI provides definitions for aeronautical activities and space flight and was founded in October 1905. Also, there is a difference between defining outer space merely by altitude, or by function, such as an object that orbited the earth and is returning. Under either approach, the balloon was not a space object or in outer space – it was violating U.S. sovereignty.

Air law is governed by several multilateral and bilateral treaties and conventions, including the 1944 Chicago Convention, the 1929 Warsaw, 1999 Montréal, 1953 Rome, and 1961 Tokyo conventions. Air law regulates airspace and aircraft operating in sovereign airspace, and nations are entitled to complete and exclusive sovereignty over their territorial airspace.

The first artificial earth satellite, launched on Oct. 4, 1957, by the Soviet Union was placed into an elliptical low earth orbit and established the principle of freedom of use of outer space. Space law is governed by several treaties and conventions, including the 1967 Outer Space Treaty, the 1968 Rescue Agreement, the 1972 Liability Convention, and the 1976 Registration Convention. Airspace and outer space are not defined in the relevant treaties.

In contrast to airspace, national sovereignty over outer space is prohibited. Space law does impose liability and oversight responsibilities, but there are limited internationally recognized safety, navigation, or security standards.

The balloon was downed by a U.S. military F-22 Raptor after the balloon had traversed the U.S. but was still in U.S. airspace off the coast of South Carolina. It was at about 60,000 feet MSL, which is clearly in airspace, not outer space, and is subject to the complete and exclusive sovereignty of the United States. Thus, shooting down the balloon was manifestly proper under international law.

If you have any questions about this client advisory, please contact a member of our Aerospace group.