This article deals with one aspect of Regulation 261/2004, namely the exemption of its Article 5(3) regarding compensation payments, particularly in case of slot postponements by Air Traffic Management (ATM). These ATM decisions can exempt airlines from compensation payments. However, opinions differ in the legal literature and case law as to when this is the case. The article examines the current opinion, especially in the German-speaking EU area, comments on the role of the Court of Justice of the European Union(CJEU) and the pending reform proposals on regulation.