Interfleet and Intrafleet Models for Crew Recovery Problems

This paper investigates the intrafleet and interfleet models for the solution of crew recovery problems during irregular airline operations. The intrafleet model groups crew members together and assigns them to flights in the same fleet. The interfleet model splits crew groups and reassigns them to flights across different fleets. Both models belong to the set covering problems with side constraints; however, the former is a 0–1 set covering problem whereas the latter is a general set covering problem. The models exhibit different computational characteristics. Various solution approaches are discussed, and a simulated annealing algorithm is developed for models that are difficult to solve. Computational results using data from a major airline show that the algorithm is able to provide effective and efficient solutions. These results also show that the intrafleet model, though widely used by airlines in practice, limits the solution space and can lead to inferior solutions. The interfleet model offers better recovery solutions for airlines under irregular operations.