Slot — Airport Slot

Airport Slot

Slots are one of aviation's most economically significant assets. At the world's busiest airports — Heathrow, Tokyo Haneda, Frankfurt — the right to operate a single daily return service can be worth tens of millions of dollars.

Slot Levels

ICAO and IATA classify airports into three levels: Level 1 (non-coordinated — no slot required), Level 2 (schedule facilitated — voluntary coordination), Level 3 (fully coordinated — mandatory slot allocation). Only Level 3 airports require slots for every movement.

The Scheduling Season

Slots are allocated for two scheduling seasons: summer (late March to late October) and winter (late October to late March). Airlines apply to the slot coordinator at the beginning of each season for their desired slots.

Grandfather Rights

Airlines that operated a slot in the previous equivalent season (and used it at least 80% of the time) have priority to retain that slot in the new season. This 'grandfather rights' rule has made established slots at congested airports effectively permanent and transferable assets.

Use-It-Or-Lose-It Rule

The 80/20 rule (also known as use-it-or-lose-it) requires airlines to operate at least 80% of their allocated slots to retain them for the following equivalent season. During the COVID-19 pandemic, regulators waived this requirement to prevent 'ghost flights' operated solely to protect slots.

A-CDM and Slot Times

In Airport Collaborative Decision Making (A-CDM) environments, slot management extends to CTOT (Calculated Take-Off Time) assigned by the Network Manager for en-route capacity reasons, and TSAT (Target Start-up Approval Time) calculated by the airport to optimise runway throughput.