Last month United opened up a new route - daily flights from BKK to HKG. Outward flight departs at 4:05pm and the return from Hong Kong at 09:10am. Being a new and just once a day service, there are special cheap fares on offer.

The problem for Hong Kong bound passengers is that the aircraft flies on to Los Angeles. So like it or not you will have extra security checks at BKK!

My Thai friend that works for United did the inaugural flight.

That is the flight I was on with a transfer in Hong Kong continuing on to San Francisco.  Even though the flight was continuing on to Los Angeles, everyone had to exit the plane in Hong Kong.  I mentioned about the increased security, which you said was because of the final destination being in the US.