Interesting news! I have always wondered that the MAD route must be a very poor route from aircraft utilization perspective. Even if they don't currently use the same aircraft every day the route still ties an A321 for almost 24 hours of which the aircraft is in the air for only about 8 hours. So makes sense to use IB aircraft as IB can still use the aircraft on other routes in MAD in the morning before MAD-HEL and in the evening after HEL-MAD. But apparently Finnair still wants to sell it as an AY flight and not ask Iberia to fully operate and just put AY codeshare on it. And doesn't MAD and BCN flights already operate with Spanish cabin crew so basically all that is left is AY catering onboard?
Also seems like AY is really getting short of aircraft (or expanding much more rapidly than earlier planned) with so many leased aircraft operating for the summer. E190 from Wideroe, A320 from GetJet and now A321 from Iberia. Anything else I missed? Edit: And of course some leased ATRs for Norra!