If an operational requirement for an oceanic application of global civil satellite navigational systems is to emerge it is almost certain to appear first in the North Atlantic airspace. Other areas of application, their time-scales or relative time-scales and their possible accuracy requirements are more difficult to anticipate. Perhaps the Central East Pacific routes or the North Pacific routes could be next in line for justification of an operational requirement in the foreseeable future. For this reason the remainder of this paper draws entirely upon the North Atlantic, but the potential application in other areas cannot be overlooked. The views expressed are those of the author and do not necessarily reflect the views of the Civil Aviation Authority.