Andriyko

Which obligation are you referring to here specifically? Airlines check that passengers have proper documentation for the destination country as an obligation to themselves - to make sure that they are not fined by that country if a passenger does not have proper documents. Airlines do not do the passenger's job of making sure that the passenger does have proper documentation to enter any particular country. It is solely the passenger's responsibility. As it is to ensure that they have enough money, insurance. warm clothes etc. That the airline permits someone to board a plane does not mean anything. People are refused entry even when airlines are satisfied that they have proper documentation - that does not make airlines in any way liable towards the passenger for bringing such a properly documented passenger to the border. Again, let's be clear here - document checks that airlines perform are not for the benefit of the passenger and are not some form of an extra check that the passenger must perform before travel. Blaming the airline rather than accepting this for what it is - a very painful lesson - does not help anyone. That BA agent may have missed that the OP did not have proper docs for Hungary is between BA and Hungarian immigration authorities. And if we're talking about any obligations, then BA did not fulfill its obligation to itself and the agent may have exposed BA to a fine.