Judgment of the General Court (Ninth Chamber) of 19 May 2021.#Deutsche Lufthansa AG v European Commission.#State aid – Aviation sector – Operational aid granted by Germany to Frankfurt-Hahn airport – Decision not to raise objections – Action for annulment – Status as an interested party – Safeguard of procedural rights – Admissibility – Guidelines on aid in the aviation sector – Doubts as to the compatibility of the aid with the internal market – Article 4(4) of Regulation (EU) 2015/1589 – Serious difficulties.#Case T-218/18.