Therefore, the European Community adopted in 1993 Council Regulation (EEC) 95/93 
on common rules for the allocation of slots at Community airports, based on the principles governing the system of slot allocation (IATA Worldwide Scheduling Guidelines), in order to ensure the access of air carriers to congested airports of the Community on the basis of principles of neutrality, transparency and non-discrimination. The slots are allocated solely by independent coordinators. In particular, this Regulation stipulates some basic rules of the slot allocation mechanism: an air carrier having operated its particular slots for at least 80% during the summer/winter scheduling period is entitled to the same slots in the equivalent scheduling period of the following year (so-called grandfather rights). Consequently, slots which are not sufficiently used by air carriers are reallocated (the so-called "use it or lose it" rule). At the same time, the Regulation promotes the access of new entrants to the airport capacity.
The "use it or lose it" rule was temporarily suspended (so-called waiver) following the events of September 11 2001, and on the occasion of the Iraq war and the SARS epidemic in 2003
On 21 April 2004, Regulation (EC) 793/2004 amending Regulation 95/93 was adopted. This Regulation focused on a number of technical issues and was intended as a first step in a comprehensive revision process. The changes primarily helped to make the slot system more flexible in terms of both allocation and use and they also strengthened the coordinator's role and the monitoring of compliance.
In 2007 and 2008 The Commission adopted Communications on the application of the Slot Regulation. The 2008 interpretative Communication clarified certain points in order to ensure a better application of the rules in force and to increase the efficient use of the available airport capacity in relation to exchanges of slots with monetary and other consideration (so called "secondary trading"), independency of coordinators, new entrants, ATFM (consistency between slots and flight plans) and local rules). Finally, the Commission stated that it will continue to monitor the functioning of the Slot Regulation and will consider whether it is necessary to make a proposal to amend it.
Due to the intensity of the economic crisis and its impact on air carriers, the "use it or lose it" rule was again suspended temporarily in 2009. Regulation (EC) No 545/2009, adopted on 18 June 2009, allowed air carriers to keep the same slots for the summer season of 2010 as attributed to them for the summer season of 2009.
In January 2004 a study was completed to assess the effects of different slot allocation schemes. A second study in November 2006 focused on the possible impact of the introduction of secondary trading on Community airports.
Further analysis carried out in 2010-2011 on how the current Slot Regulation is working has shown that the allocation system in place prevents optimal use of the scarce capacity at busy airports. Therefore the Commission is proposing changes to the current Regulation to allow for the introduction of market-based mechanisms across the EU provided that safeguards to ensure transparency or undistorted competition are established, including greater independence for slot coordinators. This will help to ensure that slots go to those carriers able to make the best use of them. Several additional measures will improve slot utilisation while ensuring a correct use of this scarce resource.
The proposals contained in the Airport package adopted on 1st December 2011
The aim of the proposed regulation is to ensure that airlines can make the best use of the available capacity. To this effect, the new proposals:
- allow airlines to trade slots with each other at airports anywhere in the EU in a transparent way;
- reform the rules designed to help new entrants access the market at congested airports. This will allow a greater number of carriers to challenge more effectively the 'dominant' carriers which have a large presence at busy airports;
- tighten the rules requiring airlines to demonstrate that they have used their slots sufficiently during the season;
- also tighten the rules on the independence of the coordinator and increase the level of transparency on slots transactions, in order to make the market work better.
- improve the information flow between slot coordinators, airports, airlines, national authorities and organisations providing air traffic control, in order to inform decisions on airport coordination and to allow the system to react better to disruptions, for example due to severe weather conditions.
According to analysis carried out by the Commission, the changes proposed could be worth €5 billion to the European economy and create 62,000 more jobs over the period 2012-2025 and would allow the system to handle 24 million more passengers a year by 2025.
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