In English law and international law, the ownership of land includes ownership of the airspace above it, by application of the maxim * a coelo usque ad centrum (from the heavens to the centre of the earth); outer space, however, is not considered to be subject to ownership.
In English law an owner has rights in as much of the airspace above his land as is necessary for the ordinary use of his land and the structures on it. Within these limits a projection over one's land (such as a signboard) can be a trespass (Kelsen v Imperial Tobacco Co  2 QB 334) and pollution of air by one's neighbour can be a nuisance (St Helens Smelting Co v Tipping (1865) 11 HL Cas 642). Pollution of air is also controlled by various statutes. There is no natural right to the free flow of air from neighbouring land, but easements for the flow of air through a defined opening (such as a window or a ventilator) can be acquired. Civil aircraft flying at a reasonable height over land do not commit trespass (Civil Aviation Act 1982 s 76(1), but damages can be obtained if material loss or damage is caused to people or property.
In international law, national airspace, including airspace above the internal waters and the territorial sea, is under complete and exclusive sovereignty of the subjacent state. As a result, apart from aircraft in distress, any use of national airspace by non-national aircraft requires the official consent of the state concerned. This can be granted unilaterally or more commonly (in respect of commercial flights) through a bilateral treaty, usually on conditions of reciprocity. See territorial waters.