A ‘slot' is simply the permission of the airport operator for an airline to land a plane and then take off – each slot is effectively a landing/take off pair. This gives not just the right to land the aircraft, but also to use all necessary airport services and infrastructure. Each slot is fixed for a particular time of day, and this is crucial for airlines in managing their schedules. Slots should help ensure the efficient and safe running of the airport, not force airline punctuality. Not all airports use slots. There is simply no need when the airport is well below capacity. Airport slots are only assigned by coordinated airports where closer management is needed.