I am a Colombian passport holder and planning to transit without luggage through BKK Airport as follows: flying from Denpasar to BKK (haven't bought the ticket yet, so I don’t know the airline) and then going from BKK to JED with Saudi Air on SV849. Do I need a transit visa to do this? If I understood it correctly there’s only one terminal in BKK hence no reason for me to pass through immigration.
Edit for anyone reading this later: there were no problems at all
Self connection without proper to documentation to enter the transit country is always risky. You are relying on certain practices and policies that are not well documented, not guaranteed and can change on short notice.
A big risk factor is that the airline for your DPS->BKK flight will not let you board. As far as they are concerned they sold you a flight from Bali to Bangkok and what you do there after you have landed is none of their concern.
You can show them your same day onward ticket and see if they accept this, but this is quite risky since they have the right to refuse it. At least I would ask the airline about this before booking the flight. Preferably you want an answer in writing.
There's indeed only one terminal at BKK, and you should be able, once you land, to pass through security and go upstairs to the departure level, if you already have your next boarding pass. If you don't, you'll have to get it from a transfer desk.
I've done it many times, including with luggage, on airlines that interline (a frequent case was Laos>BKK with Thai, and BKK>HKG with Cathay). I usually had both boarding passes (electronic for CX) so it was pretty painless. And in the few cases I didn't, Cathay has transfer desks at BKK.
YMMV, of course, depending on the airline you'll fly with from Bali.
Whether Saudi has a dedicated desk, or farms this part of operations to a partner, I have no idea.
