…
(c) have the right to compensation by the operating air carrier in accordance with Article 7, unless:
…
3. An operating air carrier shall not be obliged to pay compensation in accordance with Article 7, if it can prove that the cancellation is caused by extraordinary circumstances which could not have been avoided even if all reasonable measures had been taken.’
6. Under Article 7 of the regulation, headed ‘Right to compensation’:
‘1. Where reference is made to this Article, passengers shall receive compensation amounting to:
(a) EUR 250 for all flights of 1 500 kilometres or less;
(b) EUR 400 for all intra-Community flights of more than 1 500 kilometres, and for all other flights between 1 500 and 3 500 kilometres;
(c) EUR 600 for all flights not falling under (a) or (b).
In determining the distance, the basis shall be the last destination at which the denial of boarding or cancellation will delay the passenger’s arrival after the scheduled time.
2. When passengers are offered re-routing to their final destination on an alternative flight pursuant to Article 8, the arrival time of which does not exceed the scheduled arrival time of the flight originally booked
(a) by two hours, in respect of all flights of 1 500 kilometres or less; or
(b) by three hours, in respect of all intra-Community flights of more than 1 500 kilometres and for all other flights between 1 500 and 3 500 kilometres; or
(c) by four hours, in respect of all flights not falling under (a) or (b),
the operating air carrier may reduce the compensation provided for in paragraph 1 by 50%.
…’
7. Article 16 of that regulation, headed ‘Infringements’, states:
‘1. Each Member State shall designate a body responsible for the enforcement of this Regulation as regards flights from airports situated on its territory and flights from a third country to such airports. Where appropriate, this body shall take the measures necessary to ensure that the rights of passengers
are respected. The Member States shall inform the [European] Commission of the body that has been designated in accordance with this paragraph.