Hi Nubboy,
My examiner was unable to justify why it was safe to fly from takeoff to above msa below F speed, but unsafe to fly from msa back to the threshold using the same speed.
It's because on take off and GA, it's permissible to fly at 125% V stall (or whatever Airbus's factor is) but limit bank angle to 15 degs and you are not expected to pull speed brakes.
On the intermediate approach, you fly at a minimum of 130% V stall, bank up to 30 degs, and may pull speed brakes - hence the bigger margin.
Edit. @CP
The whole idea is that Airbus has provided us with a dynamic speed showing us exactly what you are saying, a margin that they have deemed "appropriate"
But that's the problem - it is displaying the instantaneous margin for your present "g" which will change with bank angle and speed brake usage. I'm sure Airbus would be happy for us to fly around a few knots above VLS provided we didn't bank or pull any "g" - but speed brakes usage would be prohibited.
I think I'll stick with their present flaps / speed schedule.