What is this, APU INOP situation? Someone should either connect the external aircon or at least open 2R, pronto.
Gents, GS mini is a simple trick, although embedded in the EIS. It is neither a system nor a part of the FBW. Used before any SA Airbus was drawn on paper. As you expect the HW to drop off with a subsequent loss of airspeed due to the aircraft's inertia over the ground, you brace for that with extra buffer ontop the Vapp. Delta = HW(act)-HW(rwy). No less,
no more. Benefits? Plenty:
- somewhat stable N1 along the approach
- marginal (for one flight) fuel savings
- significantly reduced noise footprint
- avoid the need to increase N1 into the flare, allowing for non-ace like handling
Yes it does provide for a low GS (and E-kinetic) threshold, but that is a completely unnecessary, fancy explanation why you want to do it, not a design objective. Well maybe, if you insist on overcomplicating things - that is usually my role!
Once again, carry an additive to Vapp, so when the airspeed drops with the HWC dying, it drops where you want it to be for the landing.
--- edit? funny fact of the day ---
"GS mini" function does actually have a tolerance of 10 kt for the delta HWC. In fact, delta(Vapp) = hwc.act - max(10 kt; hwc.rwy) / negative results are disregarded. Layman's terms:
The correction does not go below the normal Vapp;
The correction always assumes at least 10 kt HWC at the runway, regardless of the actual entered data