Hi there. Does anyone have any experience flying Iberia with a carseat in the cabin?

I am flying from Miami to Madrid with a 1-year-old. We have purchased a separate seat for the baby, and am trying to make sure that her carseat will be allowed in the cabin. I've heard that European airlines do not always allow them on.

Iberia's website only says this: "If your child occupies a seat on the aircraft, please bring with you an authorised car seat to place the child in, considering safety regulations."

Anyone know what kinds of carseats are "authorized"? Are there any specific regulations on size, brand, type, etc.? Can I use my own US-approved carseat (I have both the Chicco Keyfit 30 and the convertible Chicco NextFit), or does the carseat have to meet EU regulations? Any info that anyone can share would be much appreciated!