On page 240 of the April Journal, Wing Commander Dickie pointed out that in traffic control as we know it today, it is ground-speed and not air-speed that really matters. As he says, it is not possible for the pilot to maintain a constant ground-speed and it is for this reason that I suggest the concept whereby individual aircraft maintain constant power which, in the short term, must give constant air-speed. Slight changes in power will maintain a planned traffic pattern on any one route at any one height. Individual speeds will of course be different, and overtaking will have to be arranged by divergencies of track or height.