A method of air traffic planning, the method comprising: defining or receiving definition of an arrival network for a center airspace having a terminal radar approach control (TRACON) airspace therein, the arrival network being composed of nodes and legs therebetween, each leg representing a segment traversed by an aircraft from an upstream one of the nodes to a downstream one of the nodes, a plurality of the nodes being designated as scheduling points where one or more constraints are enforceable, the one or more constraints including a temporal separation constraint between consecutive aircraft at each scheduling point; defining for each of a plurality of aircraft, a route set including a plurality of allowed routes each of which includes a plurality of legs between an arbitrary N scheduling points of the arrival network; and determining a plan for the plurality of aircraft within either or both the center airspace or TRACON airspace, the plan including at least a sequence of the plurality of aircraft and an assigned route for each of the aircraft, the plan being determined based on the route set for each of the plurality of aircraft, and in accordance with the arrival network, and the scheduling points and constraints thereof, the assigned route of each aircraft being one of the allowed routes in the route set of the respective aircraft, wherein each of the allowed routes includes a plurality of legs between N > 2 scheduling points wherein determining the plan includes iteratively constructing partial sequences up to the sequence of the plurality of aircraft, the partial sequences being constructed from alternative sequences subjected to a bounding argument in accordance with a branch-and-bound technique. defining or receiving definition of an arrival network for a center airspace having a terminal radar approach control (TRACON) airspace therein, the arrival network being composed of nodes and legs therebetween, each leg representing a segment traversed by an aircraft from an upstream one of the nodes to a downstream one of the nodes, a plurality of the nodes being designated as scheduling points where one or more constraints are enforceable, the one or more constraints including a temporal separation constraint between consecutive aircraft at each scheduling point; defining for each of a plurality of aircraft, a route set including a plurality of allowed routes each of which includes a plurality of legs between an arbitrary N scheduling points of the arrival network; and determining a plan for the plurality of aircraft within either or both the center airspace or TRACON airspace, the plan including at least a sequence of the plurality of aircraft and an assigned route for each of the aircraft, the plan being determined based on the route set for each of the plurality of aircraft, and in accordance with the arrival network, and the scheduling points and constraints thereof, the assigned route of each aircraft being one of the allowed routes in the route set of the respective aircraft, wherein each of the allowed routes includes a plurality of legs between N > 2 scheduling points wherein determining the plan includes iteratively constructing partial sequences up to the sequence of the plurality of aircraft, the partial sequences being constructed from alternative sequences subjected to a bounding argument in accordance with a branch-and-bound technique.