The flight schedule, specifying the flight legs to be
flown and the departure time of each flight leg,
largely defines the competitive position of an air-
line and is thus a key determinant of airline prof-
itability. Designing a profit maximizing flight sched-
ule, however, is extremely complex. It affects and is
affected by essentially all aircraft and crew schedul-
ing decisions of the airline, and competing airlines as
well. No single model has captured all these inter-
dependencies, and even if such a model were for-
mulated, it surely would be intractable. Moreover, its
input data requirements are impractical, requiring, for
example, accurate estimates of itinerary-specific pas-
senger demands, spill costs, and recapture rates.
Notwithstanding this complexity, flight schedule
design and variants of the problem have been of
interest to researchers for many years, with Simp-
son (1966), Chan (1972), Soumis et al. (1980), and