Originally Posted by
Scifience
I've done this at HKG and NRT a few times. I've never had to do anything more than tell some guard what I wanted to do to be let back into the arrivals hall (and, of course, go through entry immigration again). In NRT, you just go backwards through the transit security checkpoint. HKG is the same.
That is not true. I have made my own experience at HKG.
It is not allowed to exit the airport after you have entered the secure departure area. You may only leave if an airline representative escorts you out (e.g. in cases like irrops).
Last December I had a 12 hour connection at HKG. After arrival I went through transit security to access a lounge (for showering and eating) in the departure area. After the lounge visit I wanted to head out for the town.
There was no way or channel to exit the departure area.
I had to find an airline representative, who then took me through a special door near the transit security zone. A security officer checked my documents, noted my details and let me pass into the arrival zone (before entry immigration).