Season Planning


Below you find some basic information about the sequential proceeding of each season planning step:

Historical Precedence

The core of the slot allocation process is the use of historical precedence ("grandfather rights"). This precedence applies only to equivalent, and not consecutive, schedules seasons (e.g. Summer to Summer season) and is limited to the equivalent period and days of operation. This principle entitles an airline to claim a series of slots within the same coordination parameter(s) in the next equivalent schedules season, provided that:

  • the slots were allocated for regular scheduled services forming a series of slots
  • at least 80% of the slots were operated by an airline as cleared by the coordinator, and may include the observations and results of the seasonal slot performance monitoring

source: IATA Worldwide Slot Guidelines para 8.7

Submission for New Season

About six month before the start of the respective schedules season, airlines provide coordinators with their schedule clearance requests for the arrival and departure times required at the airports concerned. The submission is sent by the airline to the coordinator as a defined standard message format, called SCR (Slot Clearance Request).

Initial Coordination

The coordinator collates this information and identifies periods in which slot requests exceed declared airport capacities. Slots are allocated according to the recommendations of the IATA Worldwide Slot Guidelines and in Europe according to the respective EEC95/93 Council Regulation and amendments. All airlines are informed about their allocated slots latest 12 days prior to the start of the upcoming slot conference.

Post SAL Activity

Post SAL activity can only take place following the distribution of the allocation of slots (SAL) to all airlines and should end three days prior to the start of the slot conference.

source: IATA Worldwide Slot Guidelines para 9.10

IATA Slot Conferences

Organised by IATA, the Slot Conferences are held twice each year (June and November) about five months before the start of the respective schedules seasons. During the 3 days "working conference", schedules are adjusted mainly through bilateral meetings between airlines and coordinators regarding alternatives offered, or between airlines to exchange slots offered or accepted. A schedule change at one airport must affect one or more other airports. Because usually all coordinators attend the conference, it provides the best forum in which all such repercussive changes can be quickly and efficiently processed, and airlines can leave the conference with firm schedules which they consider are the best compromise between what is wanted and what is available. The entire process is based on consensus and aims to be flexible, fair and open.

Slot Return Deadline

Airlines must not hold slots which they do not intend to operate, transfer or exchange, as this could prevent other airlines from obtaining slots. If an airline becomes aware that for whatever reason it may not be able to use a slot, or series of slots, the airline must advise the coordinator, and return any slots it knows it will not use. Unwanted slots must be returned no later than 15 January for the next Northern Summer season and no later than 15 August for the next Northern Winter season.

source: IATA Worldwide Slot Guidelines para 9.15

Historics Baseline Date

The series of slots held by an airline on 31 January  for the following Summer scheduling period, or on 31 August for the following Winter scheduling period, is used as the basis for determining eligibility for historic precedence.

All cancellations made after the Historics Baseline Date are considered as non-utilization of the series of slots in the 80% usage calculation, unless the non-utilization is justified for any of the following reasons:

  1. Interruption of the air services of the airline due to unforeseeable and unavoidable causes outside the airline’s control, for example a closure of an airport or airspace or severe weather; or
  2. Action intended to affect these services that prevents the airline from carrying out operations as planned, for example, industrial action or strikes.

source: IATA Worldwide Slot Guidelines para 8.7.3

see also season planning calendar