Originally Posted by 82spukram

Climb
This how ground speed mini works. If you put a Value in Vapp you still get ground speed mini.

Sunvox hope this helps some as far as what the bus is thinking.


Approach autothrust:
Below 3200 ft. radio altitude, with at least CONF 1, the A/THR logic is modified to be more responsive to speed variation. This is referred to as approach autothrust.

Speed Mode In Approach Phase
When the aircraft flies an approach in managed speed, the speed target displayed on the PFD in magenta, is variable during the approach. This managed speed target is computed in the FMGS, using the “ground speed mini function”.
Ground Speed Mini Function Principle
The purpose of the ground speed mini function is to take advantage of the aircraft inertia, when the wind conditions vary during the approach. It does so by providing the Crew with an adequate indicated speed target. When the aircraft flies this indicated speed target, the energy of the aircraft is maintained above a minimum level ensuring standard aerodynamic margins versus stall.
If the A/THR is active in SPEED mode, it will automatically follow the IAS target, ensuring an efficient thrust management during the approach.
The minimum energy level is the energy level the aircraft will have at touchdown, if it lands at VAPP speed with the tower reported wind as inserted in the PERF APPR page.
The minimum energy level is represented by the Ground Speed the aircraft will have at touchdown. This Ground Speed is called “GROUND SPD MINI”.
During the approach, the FMGS continuously computes the speed target, using the wind experienced by the aircraft, in order to keep the ground speed at or above the “Ground Speed Mini”.
The lowest speed target is limited to VAPP and its upper limit is VFE of next configuration in CONF 1, 2, 3 and VFE - 5 in CONF FULL.
The speed target is displayed on the PFD speed scale in magenta, when approach phase and managed speed are active. It is independent of the AP/FD and/or ATHR engagements.
Wind is a key factor in the ground speed mini function.
TWR Wind
It is the MAG WIND entered in the PERF approach page. It is the average wind, as provided by the ATIS or the tower. Gusts must not be inserted, they are included in the ground speed mini computation.
TWR Headwind Component
The TWR HEADWIND COMPONENT is the component of the MAG WIND projected on the runway axis (landing runway entered in the flight plan). It is used to compute VAPP and GS mini.
Current Headwind Component
The actual wind measured by ADIRS is projected on the aircraft axis to define the CURRENT HEADWIND COMPONENT (instantaneous headwind). The CURRENT HEADWIND COMPONENT is used to compute the variable speed target during final (IAS target).

VAPP Computation
VAPP, automatically displayed on the MCDU PERF APPR page, is computed as follows: VAPP: VLS + 1/3 of the TWR HEADWIND COMPONENT or
VAPP = VLS + 5 knots, which ever is highest. “1/3 of the TWR HEADWIND COMPONENT” has 2 limits:
— 0 knots as the minimum value (no wind, or tailwind)
— + 15 knots as the maximum value.
The Crew can manually modify the VAPP and TWR wind values on the PERF APPR page.
Speed Target Computation
The FMGS continuously computes a speed target (IAS target), that is the MCDU VAPP value plus an additional variable gust.
The gust is the instantaneous difference between the CURRENT HEADWIND COMPONENT and the TWR HEADWIND COMPONENT. It is always positive (or equal to zero for no wind or tailwind). The IAS target is displayed on the PFD as a magenta triangle moving with the gust variation. The IAS targets have 2 limits:
— VAPP as the minimum value
— VFE - 5 kts in CONF FULL, or VFE of the next configuration in CONF 1, 2 or 3 as the maximum value.
Ground Speed Mini (GS Mini) Computation
Ground speed mini concept has been defined to prevent the aircraft energy from dropping below a minimum level during final approach. The GS mini value is not displayed to the Crew.