AnadoluJet cut planes from 14 to 11 with optimized flight scheduling.

AnadoluJet, a Turkish domestic low-cost carrier, runs a hub-and-spoke network centered on Ankara with 24 flight points and rebuilds its schedule every winter and summer. Fleet utilization and transfer-passenger waiting times pull in opposite directions; a survey found about 25% of passengers said transfer service and waiting times at Ankara needed improvement.

Bilkent University researchers modeled the problem as a mixed-integer program and then built a two-phase heuristic in Java with an Excel front end—OpScheduler—that generates weekly schedules while obeying airport, aircraft, and operational constraints.

On AnadoluJet's summer 2012 data, the mathematical model scheduled 100 flights over 24 cities with 11 aircraft versus 14 in the current schedule, raising average plane usage from 8.91 to 11.7 hours per day. City pairs offering transfers within one hour rose 23.4% with the model and 50.2% with the heuristic.

AnadoluJet adopted OpScheduler for its flight-scheduling process; fewer aircraft imply a fixed-cost reduction of about $4.8 million per aircraft per year, and freed planes can open new destinations.