I recently did something like this in Dublin. As a Transit passenger, they clear you through to a secure section of the airport where a Visa is not required.
There was no way as a passenger for me to leave this area unescorted, so I had to have someone from the airline walk me out. I was then able to go through passport control, get a Visa (which was slightly difficult, as the immigration officer was mildly annoyed that I had no location where I was staying at in Ireland that he could put on the form – he ended up putting Trinity College as I was going to sight-see and see the Book of Kells) and leave.
I left for a few hours, then returned to the airport and all was well.
Based on this experience, I would make the choice to go to the immigration first, rather than as a transit passenger, as that was the most difficult part of the whole experience for me.
Originally Posted: https://www.quora.com/Can-I-pass-immigration-into-the-airport-transit-area-leave-before-my-flight-takes-off-and-then-go-into-the-airport-passing-through-immigration
Originally Posted On: 2016-09-18