air corridor 
noun
A route to which aircraft are restricted, especially over a foreign country: the existing navigation system sends flights along rigidly fixed air corridors...
- The route was ‘The Hump’ - the treacherous air corridor over the Himalayas that claimed so many Allied aircraft that it was nicknamed ‘the aluminum trail.’
- The route of the air corridor will be specified at a later stage.
- That means heightened security at airports, flights to North America banned, private planes effectively grounded and a clear air corridor over central London with no aircraft allowed to overfly the capital.