Building airline crew rosters

Building a monthly roster for thousands of crew members, under union rules, rest limits, base assignments and pay guarantees, occupied floors of schedulers working on paper into the 1980s. It became a column generation problem, and the solver won on a criterion nobody disputes. It finds cheaper legal rosters than a person can, and it finds them for a whole fleet overnight. People still set the constraints, negotiate the rules those constraints encode, and take the calls when a roster breaks at four in the morning. The task itself is no longer done by hand at scale anywhere, which is why this line is marked by practice rather than by a score. It belongs beside airline yield pricing, the other place where a carrier handed a daily judgment to a program and never took it back.