Is there any international convention for the maximum altitude that airspace is owned by a country? It obviously can’t be infinite. Does it go to the edge of the atmosphere?
While we wait for an expert, I can share that on a recent Universe show, some guy from Palo Alto said that the Soviet Union determined the boundary with their launch of Sputnik in 1957. Before then, he said, there was controversy. But the upside of the USSR being first in space was that they had established an international legal precedent. All nations were thereafter free to fly over other nations above the atmosphere.
Airspace above 60,000 feet is Class E airspace in the U.S. That would indicate that the airspace extends to the maximum altitude that can be reached by an aircraft.
As Johnny LA notes, the US has rules that apply to any aircraft above its territory (and within 12 miles of its coast) to the limit of the atmosphere. I know of no international convention governing this (nor does Google seem to).
The “real world” answer no doubt has to do with military capabilities. Your ability to set effective airspace rules will certainly relate to your ability to enforce them (by, for example, intercepting and/or shooting down those who would flout them).
There’s no ‘official’ designation of what is or isn’t a country’s airspace that I know of, but we can set some parameters:
The official boundary of ‘space’ is 62 miles (100km), as set by the FAI. The U.S. sets its own boundary at 50 miles, for the purposes of awarding astronaut wings. Countries have recognized that orbiting in space does not violate national boundaries.
Below that, you have a limit at about 20 miles, which would be the max altitude of any spy plane, and countries generally DO consider that to be their ‘airspace’, and will shoot at spy planes who fly over at that altitude.
The space between 20 and 62 miles is undefined, primarily because it’s never been an issue. Nothing flies in that zone.
My hunch is that anything that flies under its own power (not orbiting) that crosses over the boundary into another country without permission would be considered to be invading that country’s airspace. But like a lot of things, what ultimately determines sovereignity of a region is a country’s willingness and ability to defend it. When the day comes where that zone is commercially viable or militarily important, we’ll have to negotiate new rules or risk being shot at.
Cecil’s column on airspace doesn’t directly answer this question. The closest he comes is:
This was written in 1998.