ECJ, 4 July 2018, Case C‑532/17, Wolfgang Wirth, Theodor Mülder, Ruth Mülder, Gisela Wirth v. Thomson Airways Ltd: The concept of an ‘operating air carrier’ within the meaning of Regulation (EC) No 261/2004 of the European Parliament and of the Council of 11 February 2004 establishing common rules on compensation and assistance to passengers in the event of denied boarding and of cancellation or long delay of flights, must be interpreted as not covering the case of an air carrier which leases to another air carrier an aircraft, including crew, under a wet lease, but does not bear the operational responsibility for the flights, even where the booking confirmation of a seat on a flight issued to passengers states that that flight is operated by the former air carrier.