Originally Posted by Courmisch

Within alliance, not.



That is outside alliance.

If you fly AF code on AY metal, you get access to the CDG T2D lounge and the HEL T2 Aspire lounge based on Flying Blue status or business class (as if the AY-operated flight was an AF/KL flight). I don't know if it works for non-FB SkyTeam elites.

If you fly AY code on AF metal, you get AF lounge access at CDG T2F and, reportedly, lounges at other French airports based on AY status or business class (as if you were a Flying Blue customer).

Note that this is asymmetric.