The question has been answered – by me at #19 – at least in respect of my previous employer’s operational procedures.
These EU rules and regulations were written to stop airlines:-
a) Overbooking.
b) Cancelling flights for commercial reasons.
c) Protecting passengers rights during prolonged delays.
The law is trying to legislate the unlegislable (is that a word?). Imagine a flight which is very heavily delayed because of a major mechanical defect, or crew running out of hours. Is it better (for all concerned) to cancel that flight and make alternative arrangements to reroute the passengers with a minimum of hassle, or to insist that it is just a delay and require passengers to wait until it is fixed? The prospect of statutory compensation of €250 (or €400, or €600) per passenger will help the airline make it’s decision, but it won’t necessarily be the right one.
There is a case of a UK airline having to cancel one of its daily services because of an a/c unserviceability problem. They chose to cancel the service which would involve the least amount of passenger disruption, claimed ‘exceptional circumstances’ and were ruled against – this was not the service that the particular aircraft was due to operate, and therefore the cancellation was commercial, not operational.
I recently had it put to me by a TV interviewer that aircraft maintenance problems were ‘within the control of the airline’. I asked him if, in the event that his car didn’t start in the morning, or broke down en-route, was that his fault? If it was improperly maintained, he said. Well then, I replied, aircraft operators are required by law to properly maintain their aircraft – and subject to frequent and rigorous inspection.