Daily aircraft routing for amphibious ready groups

An Amphibious Ready Group (ARG) consists of ships capable of conducting flight operations that daily require the transport of personnel and cargo (PMC) to remain operationally viable. Planning daily PMC transport for ARG ships and nearby airfields is a unique vehicle routing problem characterized by a heterogeneous capacitated vehicle fleet, two cargo types, multiple depots, time windows, and synchronized routing of two aircraft required between some but not all node pairs. We formulate this problem as an integer linear program (ILP) with an objective function that expresses the cost of flight operations and a penalty for undelivered PMC. We perform extensive computational testing using an ILP solver and a tailored ant colony optimization with local search metaheuristic on test instances constructed to represent those found in practice. We find most instances difficult to solve optimally while our heuristic provides the best known or close to the best known solution in just a few minutes. We have embedded our heuristic in a decision support system complete with graphical user interface and sent this out for use by United States Navy ARG planners.