Big Bucks!
“American Airlines employs more than 25,000 pilots and flight attendants to fly its fleet of over 600 aircraft. Crew cost is over 1.3 billion dollars per year is second only to fuel cost. In its effort to better utilize crew resources AA spent about 6000 hours of CPU time during 1989-90 running its crew-pairing code… Estimated savings generated by running this code during the past 5 years are in excess of 20 million dollars per year.
A crew pairing is a sequence of flights that starts and ends at a crew base and typically lasts 2-3 days. A crew member works 4-5 pairings per month. The most important part of efficient crew utilization is making up pairings that cover all flight legs and minimize excess cost. This problem is called crew-pairing optimization.”