Originally Posted by akcae

This is a BS answer and AA seems to do the same, claiming "extraordinary circumstances" for mechanical or other reasons under airline control. People who pursued further action in EU, including taking them to court, have won. Courts and regulatory agencies have ruled repeatedly that mechanical delays do not qualify under the "extraordinary circumstances" exception and therefore 3hr+ delay for that reason certainly entitles you to compensation under EC261/2004.

I would certainly respond and tell them you don't accept their excuse and plan to pursue via courts if they don't provide you the compensation you're due.

Also, check out the AA forum -- there's a long thread with lot of reports of people successfully getting past the BS claim and getting their compensation.