Mathematical Programming Guides Air-Ambulance Routing at Ornge

Ornge provides air-ambulance services to the province of Ontario. A major part of its services involves prescheduled transports between medical facilities. These transports almost exclusively require fixed-wing aircraft because of the distances involved and cost considerations. The requests are received in advance, scheduled overnight, and typically executed the following day. We describe our work in developing a planning tool that determines an assignment of requests to aircraft to minimize cost, subject to a range of complicating constraints. Ornge flight planners use the tool daily, resulting in substantial savings over the manual approach they used previously to develop schedules. We describe the problem, our formulation, its implementation, and the impact on operations at Ornge.