London Heathrow Airport (LHR) is renowned for its highly busy nature and lack of slots. Slots do exist, but they’re usually at less demanded times and in low quantities, unless, of course, an airline buys or leases them from another operator. The lack of capacity, along with high charges, is mainly why LHR has the world’s third-highest number of widebodies and why many airlines find it so difficult to access or grow at the airport.