Route/Market Level.• At the route or market level (e.g. London Heathrow–Paris CDG or London-Paris), the elasticity response is expected to be lower than at the price class or carrier level. Travellers faced with a travel price increase on all carriers serving a route (e.g. due to an increase in airport fees and charges), have fewer options for substitution. However, they can still choose to travel on an alternative route, while also (in some cases) having the option to use another mode of travel or simply choose to not travel.