Originally Posted by
Himeno
Don't AA, IB, BA and AY have codeshare on almost all of the others trans atlantic flights?
Yes ---- but be careful, as they (codeshare partners) don't necessarily share computer systems, and therefore check-in and checked luggage can definitely be problems.
For those on their first Oneworld itineraries, it's worth reiterating that Oneworld is a marketing campaign, with sometimes precious few operational connectivities between its "partner" airlines. Forewarned is forearmed.