Public international air law is based on two principles. The first recognizes each state’s full and absolute sovereignty over the air above its territory and territorial waters, including the right to impose its jurisdiction over such airspace. Thus, a state may require any foreign aircraft in its airspace, even if only briefly in transit, to comply with its air transport regulations, for example, those concerning the aircraft and its crew, navigation, and the environment. This right, however, is subject to those international treaty obligations the state has assumed in the interest of safe and efficient air transport. The Convention on International Civil Aviation (hereinafter referred to as the Chicago Convention), generally regarded as the Magna Charta of public international air law, requires each contracting state to “collaborate in securing the highest practicable degree of uniformity in regulations, standards, procedures and organization in relation to aircraft, personnel, airways and auxiliary services in all matters in which such uniformity will facilitate and improve air navigation.” To this end, the International Civil Aviation Organization (ICAO) was granted the power to adopt international standards and recommended practices and procedures dealing with matters such as communication systems and air navigation aids, rules of the air and air traffic control practices, as well as registration and identification of aircraft. Contracting states, however, retained the right to depart from such standards or recommended practices, provided they notified the Organization of the differences between their national regulations and those prescribed by an international standard.