How high does controlled airspace go?

[Darth Nigel]

A friend is writing a screenplay about the X-Prize (home-made spaceships) and asked me a question of matters aeronautical. Ordinarily, I would (in the finest tradition of ppruners) just make up the answer and spout forth my ignorance authoritatively, but this might be interesting.

"At what altitude do you enter controlled airspace either over the UK or USA?"

So if you were (for instance) in a home-made spaceship what was returning to Mother Earth in a controlled manner, about when would you get on the radio and ask for VFR-on-top?

(putting this here per the rubric in "Questions")

[Rollingthunder]

Up tp and including FL600 (60,000 ft) in the US.

Just guessing.

[PPRuNe Radar]

It varies. The Shanwick Oceanic Control Area is unlimited. The UK Class B is up to FL660.

[Darth Nigel]

Thanks. I shall now go bask in reflected glory!

[MikeKnight]

You may be interested to know that, although not strictly 'controlled' airspace, some Danger Areas extend from the surface to FL990.

[Arkady]

As told to me at the College of Knowledge - Controlled airspace extends to as high as you can defend!!