This article focuses on the Single European Sky (SES) and the Single European Sky ATM Research Programme - two major initiatives aiming at improving the ATM system in Europe undertaken by the European Commission. The intent of the author was to analyze and assess the application of the SES regulations since they entered into force in 2004. There were five objectives of the SES set out: to enhance safety standards and the overall efficiency of general air traffic, to optimise capacity (meeting the requirements of all users), to minimize delays, and to establish a harmonised regulatory framework. However, full benefits have not been achieved so far, mainly due to lack of genuine commitment of some EU Member States, but also to a number of issues (legal, institutional) that should be urgently addressed, The author identified some of the difficulties, which still exist. This article also discusses goals, scope and operational arrangements of the SESAR. The objectives of this project are to eliminate the fragmented approach to ATM, transform the European ATM system, synchronise the plans and actions of the different partners and federate resources. SESAR programme involves the aviation players (civil and military, legislators, industry, operators, users, ground and airborne) for defining, committing to and implementing a pan-European programme, and to support the SES legislation. In order to complete the creation of the single European sky, additional measures in the form of the SES II package by the EC were adopted. The article ends with overall conclusions concerning various aspects of the progress of the Single European Sky.