There are approximately 200 airports in Europe that can be classed as underutilized with less than 1 million passengers per annum and the majority is loss-making, publicly owned and subsidized by central or regional government. Identifying ways to increase passenger numbers, such as attracting low cost carriers is an appealing way for airport managers to improve their financial performance. Airports have large fixed infrastructure costs and studies have demonstrated that unit costs decline significantly as traffic increases up to 1.5 million Work Load Units (WLU defined as a passenger or 100kg of freight) per annum.