As far as I knew, an EU ID card from any EU member state that issues them should be sufficient documentation to enter any other EU member state directly by air. I recently pointed this out on a different site whereupon a friend answered:
National ID cards doesn’t work in all EU countries, Sweden–Ireland being a good example (speaking from experience). [sic]
I asked him (Swedish national) about the details of this travel because it goes against my expectations. Apparantly, he was flying from Arlanda to Ireland with Aer Lingus and the check-in staff at the airport requested to see his passport, were not satisfied with his (Swedish) EU ID card.
Is this a general policy of Aer Lingus not to accept European travellers with ID cards into Ireland? Was it the desk agent’s bad day? Or is an EU ID card really not a sufficient document to enter Ireland on?
Within this post, EU ID card is taken to mean national identity card issued by an EU member state to this country’s citizens.