Approach Speed Additives

[RansS9]

(Not sure if this is right place to post, if moderator has better idea no problem)

In calculating the Approach speed for a DC9 additives toVref included;

---half the steady state wind

---half the gust factor (assume gust factor is differencebetween steady state and max gust)

With minimum additive +5 and maximum additive +20.

I understand (or at least think I do) the reason for thegust factor but don’t understand thesteady state wind factor. Is this some sort of low level wind shear protection?And are these figures scalar or suitably resolved vector wind speeds ?

Thanks TIM

(If you hadn’t already worked out I don’t push heavy ironaround for a living just low hours PPl with an interest.)