Airline Crew Recovery

Problem Statement Airlines daily face the problem of how to recover when a crew's schedule is disrupted by unplanned events such as maintenance problems or severe weather conditions. These problems create a domino effect and several flights may be delayed or canceled, and aircraft and crews may miss the rest of their assigned flights. Airline coordinators then have to find a minimal cost reassignment of aircraft and crews that satisfies all required safety rules, has minimum impact on passengers, and minimizes operational difficulties for the airline. Problem Description The airline crew rescheduling problem finds a minimum cost reassignment of crews to a disrupted flight schedule while taking into account monthly flown hours of the crews, current partially flown pairings, and future assignments. The authors assume that a crew is unsplittable for the length of a pairing. Reserve crews are considered explicitly as crews with an empty pairing assigned. An entire crew is considered to have only as much time available as its most constrained member. Crews are trained for specific aircraft types, so the flight schedule includes only flight legs assigned to a single aircraft type. The problem can be modeled as a set covering problem. A row in the model represents a flight segment (i.e. one or more connecting flights that need to be covered). A column is a sequence of segments, called a pairing, flown by a particular crew and subject to Federal Aviation Administration (FAA) regulations and union contract requirements. If a pairing contains more than eight hours of flying time in any twenty-four hour period, FAA regulations and contractual restrictions require a longer compensatory rest. A pairing must start and end at the same airport, called the crew base. On United States domestic routes, a typical pairing consists of up to five duties (a sequence of flight legs followed by an overnight rest), and lasts up to seven days. In some cases, a pairing includes deadheads, which are flight legs in which the crew flies as passengers. Deadheads are typically used to relocate crews to a city where they are needed to cover a flight leg, or to enable a stranded crew to return to its crew base. A reserve crew is an on-call crew that stays at home and is ready to work if required. A reserve crew has minimum guaranteed hours paid even if no duty is performed, making it an expensive and limited …