A319/20/21 Vapp in failure cases

[anakynskywalker]

Airbus Abnormal & Emerg. proc. chapt.4 says:

"for single failure, Vapp= Vref +App spd increment+wind correction
*if APP spd increment is >=20 kts : wind correction =0
*if APP spd increment is < 20 kts : wind correction= 1/3 HWC

In case we have no "App spd increment" due to a failure (ex.one splr fault..) and no HWC that day, our Vapp will be VLS? :bored:

In the procedure and Technique chapt. it is stated :
"Vapp= Vls + wind correction. The wind correction is 1/3 of the head wind component (excluding gust) limited to 5kts as a minimum and 15 kts as a maximum."
"During autoland or when A/THR is used, or in case of ice accretion or gusty crosswind greater then 20 kts, Vapp must not be lower than Vls + 5kts"

Is there something i miss, or in case we land with: no A/THR, no autoland, single failure with no Speed increment and no HWC, we should fly at VLowest Selectable?...just 1.23 Vstall 1g?? without A/THR perhaps?

Someone can help?:ugh: TKS

[downsouth]

Well... There's something missing there... As far as I'm concerned, when calculating vapp with failures, yo actually calculate VREF + speed increment... When this spd increment is greater than 20kt you don't add the wind component nor the 5kts... However, if you look carefully at the FCOM, VREF equals the VLS for CONF FULL... But you'll end up landing with CONF 3 for most of the failures.

If there's no speed correction for a given failure, or if the speed correction is less than 20kts you still add 1/3 of headwind or 5 knts. Whatever is grater.

Nevertheless, there should be nothing wrong with landing at VLS... Actually when doing an overweight landing, you'll have to descelerate to VLS on the final approach...

A good advise when correcting for failures is (if the speed increment is less than 20kts), check the Vapp on PERF page after you've inserted the surface wind but before switching from CONF FULL to CONF 3. Add the increment to that vapp, insert the new value manualy and the switch the FLAP configuration. That way, your vapp will be already corrected for wind.

Hope it helps... And hope its right... (otherwise ill have to grap the fcoms this afternoon...)

[EMIT]

Just read what you quoted: the minimum wind correction is 5 kts, so if there is no wind at all, or even a tailwind, Vapp is VLS + 5, not just VLS.

[Zorst]

anakyn,

Oh dear...

Manuals written in French by native French-speakers, transalated into English, then interpreted by non-native English speakers.

...oh, and 1.23 Vs 1g is actually quite fast in comparison with some flying machines!

[Bruce Waddington]

Hi All,

The Airbus 320 family has some small print that needs reading with regard to determining Vapp, both in the normal and failure cases.

For normal Vapp;

The early model 320s use Vapp = Vls + 5 + wind additive (1/3 steady
headwind), max 15 kts, whichever is greater.

The later 320s, 319s and 321s all use Vapp = Vls + 5 OR wind additive (1/3 steady headwind), max 15 kts, whichever is greater.

For failure cases;

All models are the same;

If Vls additive is = or greater than 20 kts Vapp = Vls + Vls additive
If Vls additive is less than 20 kts Vapp = Vls + Vls additive + 1/3 steady state wind (not to exceed 20 kts total).

In addition, for normal cases the minimum 5 kts is only required in the following circumstances;

1. Auto trhust is used.
2. Auto land is performed.
3. Gusty crosswinds greater than 20 kts.
4. In case of ice accretion for landing in Config Full ( note minimum 10 kts for landing in Config 3).

Our outfit has a QRH page as a memory aid for all these calculations as we fly many different models.

best regards,

Bruce