Distributed planning requires both architectures for structuring multiple planners and techniques for planning, communication, and cooperation. The authors describe a family of systems for distributed control of multiple aircraft, in which each aircraft plans its own flight path and avoids collisions with other aircraft. AUTOPILOT, the kernel planner used by each aircraft, comprises several processing "experts" that share a common world model. These experts sense the world, plan and evaluate flight paths, communicate with other aircraft, and control plan execution. Four architectures are discussed for the distribution of airspace management and planning responsibility among the several aircraft occupying the airspace at any point in time. The architectures differ in the extent of cooperation and communication among aircraft.