Originally Posted by
Dave Noble
If you were on a through booking to HEL, then the airline was responsible to book you to HEL
Hmm I doubt HEL was to ultimate destination under the AA ticket. I appears to be ARN (most likely the OP had a heavily discounted ticket ex ARN/Sweden). Hence the OP booked a separate ticket ARN-LHR (rather than HEL-LHR).