Компенсация должна быть, хотя бы выдачей flight credits
However, compensation is not due if the carrier can prove that the cancellation is caused by extraordinary circumstances which could not have been avoided even if all reasonable measures had been taken. The airline has to prove this by providing, for example, extracts from logbooks or incident reports. The air carrier should give this evidence to the relevant national enforcement body as well as to the passengers concerned in line with national provisions on access to documents.