A320 approach speeds calcs

[thunderling]

I am new to the A320.

Q. What is the relationship between Vls and Vref and Vapp in the landing config?

Vref is stated as 1.23 VS config full

Vls definition not given in landing config and yet Vapp is calculated as an additive to Vls.

Is Vls simply equal to Vref???????????:ugh:

[SIDSTAR]

Read QRH 2.31 re approach speeds

[Dan Winterland]

But one thing not immediately apparent is that the Vapp comes from the FMGC and Vls comes from the FACs. Which means that if the aircraft is a different weight form the loadsheet, (and we all know how accurate those are if you're using notional weights) you may not see the 5 knot buffer between Vls and Vapp you should on your PFD.

The 321 seeems to be the worst. In my company, two or three tons difference is the norm. I have seen as much as five. Manual insertion of Vapp is common, I tend to add one knot per tonne of difference to the FMGC generated Vapp having checked the FAC generated weight.