VAPP FMS calculation?
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VAPP FMS calculation?
Hello,
Is the approach speed (VAPP) a FMS calculation, or is it a Pilot input? If it is an input, when is it done on a Airbus A320?
Thanks
LX
Is the approach speed (VAPP) a FMS calculation, or is it a Pilot input? If it is an input, when is it done on a Airbus A320?
Thanks
LX
Join Date: Sep 2000
Location: London, England
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Bom Dia,
The FMGC calculates a VAPP speed depending on weight and the surface wind which you enter in the PERF APP page. (it is VLS+5 with light winds)
If in managed speed the autothrust will command this speed on approach.(read about GS mini to see how it changes with wind)
The pilot can overwrite VAPP if required by gusty conditions (up to VLS+15 per FCOM) or in the case of abnormal situation, the QRH gives an increment to add, there is a page in the QRH describing VAPP calculation.
The FMGC calculates a VAPP speed depending on weight and the surface wind which you enter in the PERF APP page. (it is VLS+5 with light winds)
If in managed speed the autothrust will command this speed on approach.(read about GS mini to see how it changes with wind)
The pilot can overwrite VAPP if required by gusty conditions (up to VLS+15 per FCOM) or in the case of abnormal situation, the QRH gives an increment to add, there is a page in the QRH describing VAPP calculation.
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(1) Vapp= Highest of: VLS+5 or VLS +1/3 Reported Head Wind Component - max add to Vls= 15 Knots
(2) GSmin= Vapp - Reported Head Wind Component or Vapp -10 if Reported Head Wind Comp less than 10 or if Tail Wind
Vapp Target (what you see on speed tape)= higest of: Vapp(1) or (GSmin(2)+actual Head Wind Component)
Reported Head Wind Component calculated from wind data in wind box, PERF PAGE
(2) GSmin= Vapp - Reported Head Wind Component or Vapp -10 if Reported Head Wind Comp less than 10 or if Tail Wind
Vapp Target (what you see on speed tape)= higest of: Vapp(1) or (GSmin(2)+actual Head Wind Component)
Reported Head Wind Component calculated from wind data in wind box, PERF PAGE
Last edited by Wind Shear Ahead; 6th Jul 2011 at 01:26.
