Combined Assignment Models
We combined FAM and TAM into a single integrated model called ctFAM (Combined Through and Fleet Assignment Model). This model used an improvement approach and changed both the fleet assignment (the plane type assigned to a flight leg) and through assignment (the flight legs to connect in a single plane route) to improve overall profitability. Our approach used the very large-scale neighborhood (VLSN) search technique, a novel technique that identifies and evaluates billions of solutions to find the best solution within minutes.
We developed several extensions of ctFAM with greater degrees of freedom (such as allowing flight times to be changed by plus or minus 15 minutes of scheduled departure times) to create more profitable schedules. Our techniques integrated well with those used by United Airlines at that time and augmented them instead of replacing them.
- We applied this technique to data provided by United Airlines and demonstrated that the schedules generated were implementable.
- The algorithms demonstrated the potential for a $25 million to $50 million increase in annual profits.