Abstract: An airline reservation system implemented using a computer wherein reservations are controlled by a seat inventory control system. The inventory control system produces optimal reservation control using network-wide booking limits while taking into account the probabilistic nature of demand. The inventory control system, based on a concept termed Network-Based Expected Marginal Seat Revenue (EMSR), does not require the large number of variables required by the other network-based approaches, and it incorporates a probabilistic demand model without resorting to computationally intractable integer programming.