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Transferring the spacing task from the air traffic controller to the pilot can benefit efficiency and capacity. To separate a chain of aircraft, time-based rather than distance-based principles are preferred as they result in better performance in case of gradual reducing speeds in arrival streams. The present-day air traffic management systems, however, operate mainly on a spatial rather than a temporal basis, and air traffic controllers monitor the distance between trailing aircraft to determine if separation requirements are satisfied. If the disadvantages of distance-based spacing can be dealt with, the implications of introducing distance-based procedures for the current controller and pilot working environment would be much smaller than compared to time-based procedures. This paper presents the spacing reduction concept as a solution for the principal disadvantage of distance-based in-trail following, the slowdown effect. Displays and procedures were tested in a pilot-in-the-loop experiment. It is shown that distance-based spacing procedures can produce a stable chain of up to five aircraft, with very low pilot workload.