An iterativeapproachtorobustandintegratedaircraftroutingandcrewscheduling

In airlineschedulingavarietyofplanningandoperationaldecisionproblemshavetobesolved.We consider theproblemsaircraftroutingandcrewpairing:aircraftandcrewmustbeallocatedtoflightsin a scheduleinaminimalcostway.Althoughtheseproblemsarenotindependent,theyareusuallyfor- mulated asindependentmathematicaloptimisationmodelsandsolvedsequentially.Thisapproachmight lead toasuboptimalallocationofaircraftandcrew,sinceasolutionofoneoftheproblemsmayrestrict the setoffeasiblesolutionsoftheproblemsolvedlater.Also,whenminimalcostsolutionsareusedin operations, ashortdelayofoneflightcancauseveryseveredisruptionsoftheschedulelaterintheday. We generatesolutionsthatincursmallcostsandarealsorobusttotypicalstochasticvariabilityinairline operations. Wesolvethetwooriginalproblemsiteratively.Startingfromaminimalcostsolution,we produce aseriesofsolutionswhichareincreasinglyrobust.Usingdatafromdomesticairlineschedules we evaluatethebenefitsoftheapproachaswellasthetrade-offbetweencostandrobustness.Weextend our approachconsideringtheaircraftroutingproblemtogetherwithtwocrewpairingproblems,onefor technical crewandoneforflightattendants.