A320 MAC < 25%

[clonecity1]

Does your airline have a procedure for dealing with QRH In Flight Perf note that if your MAC < 25% then 2 kts needs to be added to VLS,Vapp etc?
Where do you find the projected MAC for landing?
Fuel Pred MCDU page only shows current CG which I have found can be outside the load sheet range (ie MacTow to MacZFW).
Cheers
CC1

[WildCatFromWildBush]

There are two ways:

First, use LPC W&B module. Second, use paper L&T sheet. Before flight, you always have ZFW and ZF INDEX. Landing fuel + ZFW = LW, ZF INDEX + landing fuel index = index for LW. Having both LW and it's index you will determine CG at landing.

[clonecity1]

Thank you Wild Cat.
The question is what triggers are there in your airline's SOPs to flag a landing that will be conducted with a CG < 25%.
I work for a european airline who have been flying airbus for a long time and we are blissfully unaware if we need to add 2 kts to our Vapp.
Cheers
CC1

[Citation2]

Refer to FCOM Flight Crew Bulletin : FCB-FCB17 P 3/6.

"CHARACTERISTIC SPEEDS COMPUTATION A320

VLS is computed from Weight and Vc and corrected for the current CG. ‐ If the current CG is forward of 15 %, 15 % CG is used to compute the speeds ‐ If the current CG is between 15 % and 25 %, the speeds are computed using an interpolation between 15 % and 25 % CG ‐ If the current CG is aft of 25 %, 25 % CG is used for speed computation. F, S, and Green dot are independent of CG"

[9.G]

clonecity1, I'm not aware of such SOPs but it makes sense to me. Most certainly all the handling characteristics are within certification limits etc without any additives. However with forward CG and performance being NO factor, it's considered it a good practice to select Flap 3 and add coupla knots for the sake of better controllability. On the contrary with rearward CG Flaps full is more useful and no additives as the controls are more touchy once in direct law. I remember this being merely a recommendation certainly not SOP.
It adds some elegance to your flying, methinks.

[john_tullamarine]

I think you'll find that the speed additive is due to a slight increase in stall speed as the CG moves forward.

Generally the stall speed used for performance work is based on the forward limit. There is no reason why the OEM can't do a bit more work and define sub-envelopes within the overall CG envelope to get a slightly improved performance data set across the CG range.

[Microburst2002]

this thread brings to mind something.

I'll start a thread about that in a minute. See you there I hope, guys

[thermostat]

The performance info in the FCOM is all based on 33% MAC. Why would the aircraft be at 25%? The takeoff MAC should be close to 34% so that during the flight as the fuel is burned off the MAC will move from 34% to 30% or there about. Since the performance figures are based on 33%, then the 'plane should be loaded accordingly. I would suggest reaching 33% at the midway point of the flight.