You are not entitled to a compensation if the reason for a flight delay, denied boarding or cancellation is due to ‘’extraordinary circumstances’’.
‘’extraordinary circumstances’’ mean circumstances that are outside the airline’s control.
Extraordinary circumstances are circumstances such as severe weather conditions, lightning strikes, medical emergencies, air traffic control strikes, airport employee strikes or air traffic control strikes, air traffic control restrictions, sudden malfunctioning of the airport radar, political unrest…
In law this is known as ‘’Force majeure’’ – A situation which is beyond countering by taking reasonable precautions.
Understandably, the airlines are only held responsible for things that they can control.