L 84]20 Official Journal of the European Union 31.3.2009 COMMISSION REGULATION (EC) No 262/2009 of 30 March 2009 laying down requirements for the coordinated allocation and use of Mode S interrogator codes for the single European sky (Text with EEA relevance) THE COMMISSION OF THE EUROPEAN COMMUNITIES, Having regard to the Treaty establishing the European Community, Having regard to Regulation (EC) No 552/2004 of the European Parliament and of the Council of 10 March 2004 on the inter- operability of the European Air traffic Management Network (the interoperability —Regulation) (') and in particular Article 3(5) thereof, Having regard to Regulation (EC) No 549/2004 of the European Parliament and of the Council of 10 March 2004 laying down the framework for the creation of the single European sky (the framework Regulation) (3), and in particular Article 8(2) thereof, Whereas: (1)  Mode S (Select) is a cooperative surveillance technique for air traffic control. It enables the selective interrogation of aircraft and the extraction of air derived data through which new air traffic management functionalities can be developed. The design of systems supporting addressing individual aircraft through the Mode S (here- inafter Mode S interrogators) requires the use of Mode S interrogator codes for the detection and surveillance of aircraft equipped with a Mode S transponder. (2)  To secure the safety of the air traffic surveillance system, it is essential that the radar coverage areas of two Mode S interrogators using the same interrogator code do not overlap, except if they are grouped in a cluster or if other appropriate operational mitigations are in place. (3) In order to support the deployment of an increasing number of Mode S interrogators and to resolve the problems resulting from the shortage of interrogator codes available for the interrogation of aircraft, there is a need to coordinate the allocation and use of those interrogator codes efficiently. (40 Eurocontrol has been mandated in accordance with Article 8(1) of Regulation (EC) No 549/2004 to develop requirements for the allocation and use of Mode S interrogator codes (hereinafter interrogator codes). This Regulation is based on the resulting mandate report of 2 January 2008. L 96, 31.3.2004, p. 26. L 96, 31.3.2004, p. 1. () (10) (11) Initially, for technical reasons, only interrogator identifier codes (hereinafter 1I codes) 0 to 15 were defined and used as interrogator codes. Due to the expected number of Mode S interrogators, measures were later taken to allow the use of additional surveillance identifier codes (hereinafter SI codes) 1 to 63. Normally, the use of SI codes requires that all Mode S targets within the coverage of Mode S interrogators are equipped for this purpose. However, specifications were developed by Eurocontrol for an II/SI code operation which would enable the early use of SI codes by Mode S interrogators even in an environment where all Mode S targets would not be equipped for the use of SI codes. Mode S operators should therefore be required to accom- modate this II/SI code operation. A centralised interrogator code allocation service, provided through the interrogator code allocation system, has been established under the authority of Euro- control. Member States should be required to take the necessary measures to ensure that the interrogator code allocation system delivers information supporting the consistency of the key items of an interrogator code allocation. These key items should be clearly identified. Common procedures should be defined to ensure that the key elements of the interrogator code allocations are properly implemented. They should take into account relevant provisions of the International Civil Aviation Organisation (hereinafter ICAQ). Mode S operators and air traffic service providers should take appropriate measures to detect and mitigate the effect of possible conflicts between interrogator codes. This Regulation should not cover military operations and training as referred to in Article 1(2) of Regulation (EC) No 549/2004. A limited number of interrogator codes is reserved for exclusive use and management by military entities, including intergovernmental organisations, in particular the North Atlantic Treaty Organisation. Mode S interro- gators using these codes therefore do not need to be subject to the coordinated allocation process. Member States should however be required to take the necessary measures to ensure that the use of these inter- rogator codes has no detrimental impact on the safety of general air traffic.