An exact solution method for a rich helicopter flight scheduling problem arising in offshore oil and gas logistics

Abstract This paper studies the problem of creating an optimal flight schedule for a heterogeneous fleet of helicopters tasked with transporting personnel to, from, and between offshore installations. The problem can be modelled as a rich vehicle routing problem and combines the following properties from the vehicle routing literature: pickup and delivery structure, heterogeneous fleet operating out of multiple depots, multi-trip, and temporal synchronization of transportation tasks. We present compact and extended mathematical models of the problem, where the extended model is based on generating all trips apriori. When solving the extended model we apply delayed constraint generation (DCG) to parts of the model to speed up the solution process. Computational results are presented that show that the extended formulation and solution method can solve realistic instances of the problem within one hour. The results further show that the DCG method works significantly better than using lazy constraints from a commercial solver, especially when the number of transportation tasks requiring temporal synchronization becomes large.