Non-stop flights are the first choice for passengers traveling from one cit
y to another. In the absence of such flights, passengers must take connecti
ng services (or connections) with two or more flights. A through flight is
a type of connection that uses the same aircraft for the flights involved,
which enables connecting passengers to remain onboard rather than deplaning
to locate their departure gates at busy airports. The convenience of throu
gh flights gives them a marketing advantage over regular connections. For t
his reason, airline schedulers invest significant effort in building profit
able through flights into the flight schedule. We have developed an optimiz
ation model for United Airlines for constructing the set of through flights
that maximizes the through revenue for a schedule. The model eliminates th
e manual effort involved in assigning through flights and enhances the netw
ork contribution by at least ten million dollars annually.