A noise action plan is a legally required set of measures under EU and Portuguese rules to manage and reduce environmental noise around airports, covering actions like flight‑path controls, operational limits, curfews and property insulation. A fine for Humberto Delgado Airport means regulators judged ANA — Aeroportos de Portugal — did not meet those measures; residents near the airport and those affected by flight schedules should follow the appeal process and any changes to mitigation measures.