Chiangi, that's exactly correct.

M class and above tickets can be issued open return. That's the only reason why I buy M class tickets originating in HKG. M class is the cheapest fare class you can buy and fares are often over US$1500 roundtrip to the East Coast.

And there is no fee when setting the date of travel, and you are likely to get even the most sold out dates because M (or B even, out of BKK) class is an expensive booking class.

But aren't fares ex-BKK to USA supposed to be cheap? How are they B class?

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When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.

- Leonardo da Vinci