140 min connection USM-BKK (PG) to BKK-HKG (CX)?
 

I am scheduled to arrive BKK from USM on PG on a paid ticket. I had booked a separate award ticket later that day for BKK-HKG on CX using Avios. Owing to a schedule change, my connection time was reduced to 140 minutes, which is making me a bit nervous. From searching around I believe I can clear immigration in USM and check my baggage through, which should save some time (if I'm correct).

There's no other award space showing up that day on CX so I'd like to keep the flight if possible... 140 minutes doesn't seem like it's cutting it too close but I haven't navigated BKK before and don't know what I should expect and how difficult it may be. Thoughts?

It will be no problem. Indeed, ask PG in USM to check your bag until HKG so you won't have to collect bags in BKK. Just show your CX e-ticket receipt, as the PG agent will need those info.
I've never been to USM but I don't see how you could clear immigration in USM and be differentiated from other pax just flying this domestic flight and not leaving Thailand afterwards. But, maybe I'm missing something here and there are people on this forum who are familiar with USM and will certainly be able to give you an accurate answer on this point.

Thanks - There are a few blogs and past posts that talk about immigration at USM and other domestic Thailand flights with connecting international. It looks like (at USM at least) they segregate you before boarding and give you a sticker.

USM has direct intl flights in/out, so has immigration and customs facilities. You should be able to do the Exit clearances there and then stay airside in BKK upon arrival....if PG will let you do this when you check in with them. You'll have to get a CX boarding pass in BKK at the airside Transfer Desk.

In the event PG refuses to do anything except straight domestic check-in, I think with 140 minutes you still have time to get bags at Bag Claim, get up to the CX flight check-in, and get to boarding gate. As long as the PG flight arrives pretty much on time in BKK.

You don't mention if your PG flight is morning or afternoon which is somewhat important as PG doesn't post delays until the afternoon if ever. So on that level you should be OK. Also the MCT for a dom->int flight is :

[KVS Availability Tool 7.1.2 - Reference: Minimum Connection Time [MCT]: BKK/PG-CX]
Last year leaving CNX a couple in the line next to us were connecting PG-CX and were able to check their bags through and go through immigration in CNX thereby avoiding any hassle in BKK. As jiejie has already mentioned they were not able to receive their BPs and had to go to the transfer desk in BKK. That's not a difficult task.

Regarding Goldorak's comment on the mingling of passengers that exactly what happens. You'll get your BP in USM, bags checked through, your domestic BP will be stamped with a red INTERNATIONAL mark and you'll then proceed through immigration and into the international departure area. Once boarding begins you'll indeed be sitting with domestic pax and the only indication you're connecting internationally will be a sticker on your shirt. Upon arrival in BKK you'll proceed to CIQ in concourse B or, if you get a bus gate, you'll be picked out at the top of the escalator and allowed access into the international area. From there you'll head to the WEST (IIRC) transfer security/desk to get your CX BP.

You;ve plenty of time and this should present no difficulties.

Thank you very much dsquared37 for these explanations. We learned things everyday on this forum :)
I was not aware at all of this interesting possibility at USM. But I believe it's pretty unique, isnt't it (and somewhat pretty strange also) ? Do other airports in SE Asia propose this ?

This can occur out of 6 airports in Thailand that have immigration/customs facilities. They are CEI, CNX, KBV, HDY, USM and HKT.

When arriving into BKK on an international flight and heading to one of the above airports you must go through immigration in BKK but get your bags and head through customs in the domestic airport. Upon arrival to the domestic destination you are segregated on the jet bridge; domestic pax to one carousel area and int pax to a completely separate one.

I don't know if any other SE Asia countries operate similarly.