Airbus (320) Vapp determination

[Bagot_Community_Locator]

I am bit confused about how to determine Vapp, in particular in these conditons :
- no ice accretion
- no auto-thrust
- no autoland
- nil wind
- normal conditions (ie. no failures)

FCOM 3.04.10 (operating speeds definitions) says :

VAPP = VLS + wind correction.
The wind correction is limited to a minimum of 5 knots and a maximum of 15
knots.

However, in the QRH 4.00 (Vapp Determination) it says :


Vapp = MAX (Vls +5 , Vls + wind correction)

Vls + 5 knot only if autothrust is used or autoland
wind correction = 1/3 headwind


So, according to the QRH, in the above conditions, Vapp = Vls ?

However FCOM says Vapp = Vls + 5 (minimum) ?

Now do we add the extra 5 knots to Vls (in the specified conditions) or not ?

Doesn't the QRH contradict or the FCOM or I can't read ? :confused:

[rudderrudderrat]

Hi,
Look at QRH 4.02 Landing Dist without autobrakes.
It runs through an example of the minimum Landing Distance required, without auto thrust, at VLS, using manual brakes.
If you use (VLS+5) then add 8%.

[ReverseFlight]

FCOM 3.04.10 p4 (SEQ001 REV24) says
VAPP = VLS + wind correction + 5 knotsIncrement required if autoland or A/THR or ice accretion or gusty crosswind >20kts
*
FCOM 4.00A (SEQ130 REV42) says
Vapp (2) = VLS + 5kt (1) + WIND CORRNote (1) 5kts increment required for A/THR or autoland (irrelevant in your case)
Note (2) Increment if ice accretion (again irrelevant)
*
No conflict between the two sections ?

[OPEN DES]

Check your revision number! The older a/c have 5 kt plus wind corr. The new ones 5kt/wind corr. whichever is more. (5kt only when athr used).

[Bus Driver Man]

I am bit confused about how to determine Vapp, in particular in these conditons :
- no ice accretion
- no auto-thrust
- no autoland
- nil wind
- normal conditions (ie. no failures)


If you follow FCOM or QRH, with no wind and no auto-thrust, Vapp will be Vls.
You can fly at Vls, but I don't suspect that a lot of people will do it, since you don't have a margin below your speed and your landing will not be so smooth. (However, actual landing distances are calculated with Vapp=Vls)

Where I work, we always fly the Vapp calculated by the FMGS when flying without auto-thrust. So always with the 5kts increment.
No need to calculate the Vapp if your FMGS does it for you. (No failure case)

[Microburst2002]

maybe you are checking the FCOM 3 of one MSN and the QRH of another?
there are slight differences in VAPP computing depending on the model.

[Bagot_Community_Locator]

QRH REV 42

FCOM 3.04.10 REV 24

Both apply to same SN, same model

My copy of the FCOM only says :


VAPP = VLS + wind correction.
The wind correction is limited to a minimum of 5 knots and a maximum of 15
knots.
The flight crew may modify VAPP through the MCDU.
– During autoland or when A/THR is on or in case of ice accretion or gusty
crosswind greater than 20 knots, VAPP must not be lower than VLS + 5
knots.


It does not say Vapp = VLS + wind correction + 5 knots.

My copy of the QRH says :

Vapp = MAX (Vls +5 , Vls + wind correction)

Vls + 5 knot only if autothrust is used or autoland
wind correction = 1/3 headwind


It does not say Vapp (2) = VLS + 5kt (1) + WIND CORR .

It has got 2 options :
- Vls + 5 (+ 5 if auto-thrust)
- Vls + wind correction
whichever is greater.

I am confused about the FCOM statement + wind correction" minimum of 5 knots.

That this mean :
a - you always add a minimum of 5 knots for wind correction ? (wind or no wind)
or
b - you only add the 5 knot minimum wind correction only if any wind ?

I interpret the FCOM that you always must apply a min 5 knot wind correction, from the statement The wind correction is limited to a minimum of 5 knots

However I interpret the QRH as saying you don't need the + 5 knots if no wind and no auto-thrust.

[Bus Driver Man]

FCOM 3.04.10 is the chapter of Operating Speeds Definition.

Read the entire definition:

VAPP
Final approach speed
Displayed on MCDU APPR page
Calculated by the FMGCs
Represents: Vapp = Vls + wind correction
The Wind correction is limited to a minimum of 5 knots and a maximum of 15 knots.
The flight crew may modify Vapp through the MCDU.
– During autoland or when A/THR is on or in case of ice accretion or gusty
crosswind greater than 20 knots, VAPP must not be lower than VLS + 5
knots.


To me, this means that the FMGC will always add 5kts minimum to the Vls for the Vapp calculation. So it will always cover the 5kts increment for autoland, auto-thrust and gusty crosswind, since it doesn't know if you will fly with auto-thrust or not or if you have gusty crosswind.

If you want to calculate the Vapp yourself, you're in the wrong chapter of the FCOM. Calculation is explained in the QRH.
FCOM 3.04.10 is only the definition of Vapp, not the calculation.

So in case of:
-No wind
-Approach without auto-thrust
-No ice
the FMCG will give you a Vapp = Vls + 5kts.
You can however change the Vapp in the MCDU to a manually calculated Vapp = Vls according QRH.

The only reason for landing with Vls I can think of, would be a very short runway. (Close to required landing distance)
Or according overweight landing checklist.




Not sure if I'm correct, just my opinion about it.

[JMEN]

If your doing a half decent rating ask your instructor!

Oh and SmartCockpit - Airline training guides, Aviation, Operations, Safety (http://www.smartcockpit.com) is a great aid.

:\

Actually even if your doing a 2bit rating, ask your instructor.

[Bagot_Community_Locator]

ask your instructor.

I won't bother.

Whilst doing my type rating, I asked my instructor many questions.

Often she couldn't answer and would have to ask someone else.:confused: Other times she would answer but then you look it up in the books to realise she gave the wrong answer. :eek: She had no time on type either apart from the simulator type rating. Why bother. :(

Welcome to low cost training :{

I think pprune (tech log) is the best resource :ok:

[Lookleft]

BCL obviously an Aussie so I am guessing that you are doing your endo at an American aircraft manufacturer's facility in Brisbane? You are correct that you will get better info from Tech Log.

[Microburst2002]

amazing

so the mistery is that the + 5kt is considered as a part of wind correction, right?

[JMEN]

I hope you are joking!

How the fcuk can a type rating instructor not know the basics.

Go on ask what the max application to Vapp is, that should get you an interesting answer.

If its not a joke, a Aussie type rating or O/S?

It is :mad:!

[ReverseFlight]

an American aircraft manufacturer's facility in Brisbane... and they charge $5000 over their competitor just for the privilege of including a printed set of FCOMs instead of loading them on a USB stick for no extra charge ... :}