What is slot allocation?

A slot is the permission given by the coordinator for an aircraft to arrive or depart at a coordinated airport at a particular time on a particular day.  There are four coordinated airports in the UK:  Gatwick, Heathrow, Manchester and Stansted, and one coordinated airport in the Republic of Ireland: Dublin.

The process of slot allocation is designed to achieve the maximum utilisation of scarce airport capacity within an acceptable level of delay. 

Back to top

Who are ACL?

Airport Coordination Limited (ACL) is an independent organisation which provides data collection, schedules facilitation and slot allocation services at UK airports and elsewhere, in accordance with national and European Regulations and the IATA Worldwide Scheduling Guidelines.

ACL was the world’s first independent organisation responsible for slot allocation and its business model, organisation and structure has been copied by many other newly-formed coordination agencies in Europe.

ACL is a private (or quasi-private) body carrying out a public function. It contributes to the debate on issues of national policy, within the scope of its responsibilities, and it is called upon from time to time to submit its views on aviation policy issues and to participate in consultation procedures. 

Back to top

Which airports are currently served by ACL?

ACL currently provides services at the following airports in the UK and Republic of Ireland:



Belfast City Glasgow
Belfast International Heathrow
Birmingham Jersey
Bournemouth Leeds Bradford
Bristol Liverpool
Cardiff London City
Cork London Luton
Doncaster Sheffield Manchester
Durham Tees Valley Newcastle
East Midlands Shannon
Edinburgh Southend
 Exeter  Stansted
















 ACL also provides services for various airports outside the UK, and at other airports in the Republic of Ireland.  For information relating to these airports, please see the ACL International website www.acl-international.com

 Back to top


 Who are the members of ACL?

The current members of ACL are:


British Airways

Virgin Atlantic Airways Monarch Airlines
Thomson Airways Thomas Cook Airlines
 EasyJet Jet2







Back to top


What is the relationship between ACL and the Airport Operators?

ACL is appointed by the airport operators to provide slot allocation, a schedules facilitation service, or a data collection service, under a service contract.

The airports pay an annual fee to ACL for these services, which include the supply by  ACL of schedule data, gathered from airlines, which is passed as a data feed each night to the airports.

Back to top

How is ACL funded?

ACL is a non-profit making organisation and only earns sufficient revenue to cover its annual operating costs.  ACL´s turnover is approximately £2.3 million annually.

The majority of ACL´s funding (approximately 70 percent) comes from the airports for which it provides services.

The airline Members which own ACL provide approximately 20 percent of its operating revenue, through annual subscriptions.  Airline Members subscribing to ACL pay a financial contribution in proportion to the number of slots they hold.

ACL Members are not involved in slot allocation decisions, and do not have any preference or advantage in obtaining slots, over those airlines that are not Members.

Approximately 10 percent of ACL´s revenue is generated from other activities, including training, consultancy and data sales.

Back to top

What benefits do ACL´s airline Members receive for their financial contribution to ACL?

 No Member airline receives any preferential treatment in slot allocation decisions made by the Coordinators in ACL.

All airlines are treated equally, in accordance with UK and European Slot Regulations, which ensure that decisions made by ACL are made in a ´neutral, transparent and non-discriminatory way´.

Members believe that it is reasonable for them to contribute to the cost of slot allocation in the UK, since the cost of the coordination task in other countries is borne by their Governments or national carriers.

Having airlines contributing toward the cost of ACL avoids the need for any Government intervention or control of slot allocation system, and ensures that all the airlines receive a high quality coordination service.

Any airline may apply to join ACL, and the Company is pro-active in seeking to expand its membership base.

Back to top

Since ACL is owned by UK airlines, isn´t it true that UK airlines will get priority over slots?

 ACL´s Member airlines have no involvement in slot allocation decisions.

The Member airlines have appointed a number of individuals as Coordinators in ACL, who act independently in making their slot allocation decisions at the airports for which they are responsible.

The slot allocation decisions made by the ACL Coordinators are transparent and open to scrutiny by any airline as well as by the airports and Regulators.

The Coordinators have a legal duty of neutrality and nn-discrimination between carriers and are responsible for giving fair and equal treatment to scheduled/charter, international/domestic, long-haul/short-haul and UK/overseas carriers alike.

Back to top