CHC and I were in Bangkok recently and we had the chance of trying out Thai Airways on their new Airbus A350-900. We were booked in Economy Class (Q class fare, which is a semi-flex fare) and knowing of Thai Airways’ same day walk up upgrade, we decided to give it a try.
You can check the seat availability on Expertflyer before travelling to know how full the cabin is but 48 hours before flying, this info is no longer available and one can only check at the check in counter (on the day of flying).
That Time Of The Year! 