In late May, I will take Aer Lingus from the US to Manchester, stopping first in Dublin and then taking a connecting flight to the UK. I believe I do not go through passport control in Ireland because I'm taking a connecting flight and traveling in the Common Travel Area. I'll only go through passport control in the UK. Is that correct? Thank you.
Just the opposite.
You will go through immigration in Dublin but will not have to go through immigration in Manchester. Entering Ireland also gives you permission to enter the UK.
The flight from Dublin to Manchester is just like a domestic flight.
Frank, thank you.
not knowing how long your stay will be, by entering via Ireland you will have the Irish admission length which is lower than the UK 6 months.
You will still need an ETA.