Originally Posted by christep

It hasn't changed. On most regional routes some flights are planned with 3-class planes and sold as 3-class (NRT, KIX, SEL, MNL, SIN, BKK, JKT, TPE, etc) but there are a few routes where 3-class planes occasionally turn up but F never seems to be sold. DPS is the main one, but also occasionally I think CEB and maybe some others.

CX very, very rarely upgrades unless the classes below are overbooked.