In which cases of flight delays am I entitled to compensation?

Following the ruling of the European Court of Justice (Fourth Section) of November 19, 2009 on compensation for passengers in the event of prolonged delay, the right to compensation was established, similar to the provisions for some cases of flight cancellation, also for passengers who reach their destination three hours later than the published arrival time. This right, however, ceases if the airline proves that the prolonged delay occurred due to exceptional circumstances, such as adverse weather conditions, sudden and unforeseeable failures of the flight from the point of view of safety and strikes (as foreseen by the points 14 and 15 in the introduction to Regulation 261/2004).