ABSTRACT
NATIONAL AIRSPACE The invention of the balloon and more especially the airplane made it necessary to clarify the rights of states in the air above their territory. As with any newly emerging area of concern, writers advanced a number of theories: (1) states had complete freedom in airspace, just as on the high seas; (2) states could claim territorial jurisdiction in airspace up to about 1,000 feet above the ground, with the upper air again free, as in the case of the high seas; (3) states could claim the entire airspace above a state with no upper limit, but only with a servitude of innocent passage granted to all aircraft registered in friendly foreign countries; and (4) states had absolute and unlimited sovereignty over national airspace, with no upper limit.1
