AIRCRAFT CARRIER - WASHINGTON CONFERENCE RESTRICTIONS Restrictions on aircraft carriers formed part of the Washington Treaty (q.v.). These restrictions implied that the aircraft carrier is now recognized as a definite and essential unit in a modern fleet. The other naval Powers followed the British lead in building this type of war vessel, and the aircraft carriers in service and building in 1928 for all Powers are shown in the table given. This table is restricted to aircraft carriers proper, the earlier and smaller vessels being excluded. (E. T.-D'E.)