The Legal Principles Governing the Control of National Airspace and Flight Information Regions and Their Applications to the Eastern Mediterranean
Dr. Nicholas Grief
Professor of Law, Bournemouth University
Barrister-at-law, Doughty Street Chambers, London
October 2009


It is a fundamental and universally recognised principle of international law that ‘every State has complete and exclusive sovereignty over the airspace above its territory’. As Shawcross & Beaumont state, ‘the concept of sovereignty is the key stone upon which virtually all air law is built, since any flight in international aviation requires the prior consent of the State overflown, which is generally granted by treaty.’ The territory of a State consists of ‘the land are as and territorial waters adjacent thereto under the sovereignty… of such State’.

The corollary of this principle, the international status of the airspace above the high seas, is equally well established. The airspace of the high seas, like the subjacent waters, is not subject to the territorial sovereignty of any State. The airspace of the high seas is the airspace above ‘all parts of the sea that are not included in the exclusive economic zone, in the territorial sea or in the internal waters of a State’.

Since the high seas are open to all States, the legal regime is characterised by the principle of freedom. One element of the freedom of the high seas is the freedom of overflight. The freedom of overflight is not absolute, however. It must be ‘exercised by all States with due regard for the interests of other States in their exercise of the freedom of the high seas’.

The airspace of the high seas being an international space, aircraft flying there are generally subject to the exclusive jurisdiction of their State of registry. This corresponds to the legal status of ships on the high seas; where the rule of exclusive flag State jurisdiction applies save in exceptional cases expressly provided for in international treaties (e.g. hot pursuit). Like warships on the high seas, military aircraft in the airspace of the high seas have complete immunity from the jurisdiction of any State other than their State of registry.Since the legal status of airspace reflects that of the subjacent land or waters, the issues of delimitation and legal regime are inextricably linked. Territorial disputes between States can endanger civil aviation, as illustrated by the long-standing Aegean Sea airspace dispute. Turkey insists that Greek airspace extends only 10 km (6 miles) offshore, whereas Greece claims that it extends 16 km (10 miles). In May 2006 Greek and Turkish F-16 fighters collided at about 27,000 feet over the southern Aegean Sea, some 21 miles southeast of the island of Karpathos. Greece said that its planes had intercepted Turkish aircraft in Greek airspace, whereas Turkey claimed that the Greek planes had interfered with Turkish manoeuvres in international airspace. A Greek pilot was killed. An Olympic Airways pilot was quoted as saying: ‘We obey the rules of the sky, but the fighter pilots do not.’ And a Greek air investigator observed: ‘There is very limited space over the Aegean Sea and its air corridors are very crowded. It is only a matter of time before a warplane crashes into a commercial plane.’