Up an Down Operator:
I think your mixing up things.
THRCLB1/ THRCLB2/THRCLB are obviously Auto Thrust related Modes. Left column on the FMA.
Don't know why you are writing about OP CLB and V/S Mode, as they are Vertical Functions of the Autopilot? 2nd column f.l.t.r on the FMA.
Those Modes weren't part of the question posted by "Check Airman"
Maybe you should accept the fact that you, as the rest of us, don't know everything about the bus!!! - so please come down from your high horse
FACT is that FMGC's, as mentioned just above comes with a lot of different costumer modifications, and none of the A319 that I fly has the selection of derated climb. Hence, the only way we can reduce climbtrust from full pwr is to go into V/S.
UP and Down Operator, I thought only Boeing boys had to worry about stalling?
I wish
I think they have more to worry about in general as some thinking is still left with the jockeys, but this v/s thing is one of the few "catch-outs" on the bus where people have spilt their coffee all over the place after having forgotten the selection and then flown into a high altitude stall. It is not recommended at high altitude and rarely nessesary as the climbrate above FL 250 is down around 1500-1800 ft/min anyway.
I don't know however, if the cost index becides setting cruise speeds ect also have an effect of the thrust output???