The surveillance of the air space by ground-based radar is important in air navigation and its military applications may be particularly mentioned since they have led to many important investigations, while aspects of the problem of less military significance have been neglected. Shore-based radar has also been applied to the surveillance of shipping in congested areas, captains and pilots being advised by VHF telephone though the captain retains full responsibility. This brings out a fundamental difference between the sea and the air. Air navigation and the ground control are integrated and the responsibility is shared. At sea the responsibility remains with the captain, and the use of radar increases this responsibility although ships are not yet obliged by law to be equipped with radar. Several court rulings have penalized the incorrect use of radar because of the greater responsibility that its availability entails and the recommendations of the Conference on Safety of Life at Sea (1960) concerning the Collision Regulations must also be remembered.