There were more pictures and human observations. Behaviour was consistent with the GSmini function adding a margin on top the Vapp from MCDU. It is possible to modify MCDU Vapp to VLS, VLS+5 (auto), VLS+10 (15?) and observe.
The margin (GSmini adjustment) was observed to be the difference between actual HWC and HWC assumed at the runway threshold.
The assumed RWY HWC was the greater of
- expected HWC component calculated based on the MCDU W/V entry
- the low limiting value of at least 10 knots.
= Max ( HWC.rwy ; 10kt )
Your suggestion does not fit the pictures already provided, the cut-off would be 5 knots. Check the first one, 1590 RA.
VLS = 128 Vapp = 133
HWC.rwy = 22
HWC.thr = 0
present day FCOM
delta HWC = 22
Vapp + 22 = 155 ===>>> not observed
Vls anchor option
delta HWC = 22
Vls + 22 = 148 kt ====>>> not observed
Bulletin 10 kt cut-off
assumed HWC.rwy = 10 kt
delta HWC = 12 kt
Vapp + 12 = 145 ====> visible on the picture
Followed by the other picture RA1510, with manually inserted 10kt HWC at THR into the MCDU. The magenta triangle on speed-tape blinked for recalculation but came back to the same position 145 kt. ,
Changing MCDU HWC.rwy from 0 to 10 kt caused a new computation with an identical result.
Last edited by FlightDetent; 3rd Jan 2020 at 09:26.