Originally Posted by
IslandPilot
Possible reason for being unable to book SEN-DUB-USA is that it would incur the iniquitous UK APD Tax. Treated as two separate bookings you only incur the 3 euro Irish APD on the DUB-USA leg and have the advantage of pre-clearance in to the USA at DUB.
With respect, that's not a reason for being
unable to book, it's perhaps a reason for
choosing to book separate tickets rather than a through ticket (*). Aer Lingus promotes through connections between all their other UK destinations and the US, so there's no reason to expect that this will not be the case here - as Jamie2k9 says, the connecting fares are likely to be loaded over the coming days.
(*) knowing of course that by doing so, one is taking the missed-connection risk.