Introduction

The coordination process between airlines and airport coordinators is described in the IATA Worldwide Scheduling Guidelines (WSG) which contains a set of procedures and time frames to provide guidance for the management of the allocation of scarce resources at busy airports. The communication between airlines and coordinators is outlined in the IATA Standard Schedules Information Manual (SSIM) which is constituted under IATA Passenger Services Conference Recommended Practice 1761b that was declared effective July 1, 1972.  Standard message formats have been agreed to allow airlines, airport coordinators and schedule facilitators to exchange airport coordination and schedule movement information electronically. The message formats are integrated into an iterative (sequential) set of request and reply messages and have been designed to provide as much clarity as possible for the message users. The received message details can be processed either by computer or by manual methods. The rules for the use and composition of the messages, together with detailed specifications and examples, are explained in chapter 6 of the SSIM.

see also About SCR Messages

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

Historical Precedence ("Grandfather Rights")

The core of the slot allocation process is the use of historical precedence. 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 Scheduling Guidelines para 6.8.1.1

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 either by SITA telex or email as a defined standard message format, called SCR (Slot Clearance Request).

Initial Coordination (Seasonal Planning)

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 Scheduling Guidelines and in Europe according to the respective EEC95/93 Council Regulation and amendments. All airlines are informed either by SITA telex or email about their allocated slots prior to the start of the upcoming schedules conference.

Pre-Conference Activity

Pre-conference activity can only take place following the distribution of the allocation of slots (SAL) and should end four days prior to the start of the schedules conference to enable airlines and coordinators to travel to the conference. The scope of the pre-conference activity at coordinated and schedules facilitated airports is limited and must not include discussions about airline strategy/plans, suggestions for schedule improvements, new slot requests, significant changes to allocated slot timings or significant increases in aircraft capacity.

source: IATA Worldwide Scheduling Guidelines para 6.9.2

IATA Schedules Conferences

Organised by IATA, the Schedules Conferences are held twice each year (June and November) about five months before the start of the respective schedules seasons. The conference represents approximately 200 worldwide coordinated/schedule facilitated airports and 250 airlines and will be attended by about 800 delegates in total. During the 3 1/2 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 Handback 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 handback any slots it knows it will not use. Unwanted slots must be returned no later than January 15 for the next Northern Summer season and no later than August 15 for the next Northern Winter season.

source: IATA Worldwide Scheduling Guidelines para 6.10.3

Start of Use it or Lose it Calculation

A series of slots which have been allocated to an airline will not be granted historic precedence in the next equivalent scheduling period, unless the airline can demonstrate to the satisfaction of the coordinator, that they have been operated, as cleared by the coordinator, for at least 80% of the time during the period for which they have been allocated.

Slots held by an airline on January 31 for the following Summer scheduling period, or on August 31 for the following Winter scheduling period, will be taken into account for the purposes of the usage calculation.
In calculating 80% usage for the series of slots as outlined above, slots not used will be treated as operated, if the non-utilisation is justified for any of the following reasons:

• (a) Interruption of the air services of the airline concerned due to unforeseeable and irresistible causes outside the airline’s control, for example, cancellations due to weather
• (b) Action intended to affect these services, which prevents the airline from carrying out operations as planned.

source: IATA Worldwide Scheduling Guidelines para 6.10.7

see also Schedules Planning Calendar