Landing slots or Airport slots are rights allocated to an entity by an airport or government agency granting the slot owner the right to schedule a landing or departure during a specific time period.
Landing slots are allocated in accordance with guidelines set down by IATA's Scheduling Services Group. All airports worldwide are categorised as either Level 1 (Non-Coordinated Airport), Level 2 (Schedules Facilitated Airport) and Level 3 (Coordinated Airport).