Originally Posted by
Pilat
As mentioned by a previous poster, above FL250, VREF40 +100 is the recommended minimum holding speed. This is because (from memory), above FL250 the amber indication on the speed tape doesn't consider thrust, and you can end up on the wrong side of the drag curve.
It doesn't consider g-load. The red bricks will fluctuate with an increase in wing load but the amber bar won't.