"LDG DIST PROC... APPLY" - a320 question

[WhySoTough]

Hi everyone.
Firstly I apologize to ask what may seem to be a silly ques to a lot of guys on here, but I'm very confused with this, and would like to understand this topic fully before my TR course.

When in case of a dual hydraulic failure, slat or flap locked, or whatever it is, and you see "LDG DIST proc.. Apply"
What exactly must be done?

Firstly the ECAM already gives you the app speed, VREF + 25 for example.
You add 25 to your VLS and put that as Vapp in the perf page, this correct?

What next do we do?
Also I see a section on the QRH with VAPP calculation, and one with VAPP determination. :ugh:

So confused.
Can someone please explain this to me?
Sorry for being annoying.
Thanks in adv

[Cough]

When is says that, use the QRH tables to work out the landing distance required, given the actual failures you have. You can cheat in the case of a dual hyd fail as the LDR is given in the summary...

[I-2021]

Hi,

When in case of a dual hydraulic failure, slat or flap locked, or whatever it is, and you see "LDG DIST proc.. Apply"
What exactly must be done?

refer to your QRH under Abnormal Procedures, ABN-80 Miscellaneous and there you will find "VAPP calculation". If you follow the flow depicted there you will apply all the appropriate correction factors. In your specific example since the Delta Vref is higher than 20kts you got it right by saying VLS+25, but my suggestion is to refer always to this table, especially in high workload scenarios where your memory could play some nasty tricks. Once you've got the speed, you insert it as you said as VAPP and then if you need to use flaps 3 for landing you select CONF3 from the PERF page menu. You need the landing distance required as well, that you will get from the summary in case of a complex failure (Dual hydraulic, emer elec conf). In the other cases you will need to get the correction factor from the LDG CONF/APPR SPD/LDG DIST TABLE according to your failure and then multiply it by your actual landing distance without autobrake CONF FULL (always regardless of your flaps lever position for landing).

Cheers.

[320p]

hello,
On this topic,what is the significance of feeding the Vapp in the MCDU in dual Hyd failure? Because, in this failure flaps/slats are selected with selected speeds.After the final flap setting do we continue with selected Vapp in which case Vapp on MCDU has no role or do we manage speed,in which case the Vapp fed in MCDU becomes relevant?
Thanks.

[Trust me Im Staff]

Hi WhySoTough

You're question is a good one in that many bus pilots ponder the same question.

After fifteen years of being a bus driver I'll give you the skinny on that table.

First of all the chart depicting Vapp determination with speed additives is purely in place if you experience dual FMGS failure and have no Vls speed depicted on the MCDU perf page. It's good To know its there and as others have explained know how to use it but it's purely backup. Use the Full flap VLS for speed additives after Youve properly sequenced the flight plan with correct destination.

The landing distance requirement is exactly what it implies, since you are increasing your approach speed due to an abnormal for example, you're checking on how much runway your specific malfunction requires you to safely land on. With any abnormal you would use the Config full "Autobrake Off" landing chart ( for maximimum braking effort after landing ) to determine your landing distance.

Hope this helps.

T

[Ollie Onion]

Trust Me,

I am glad you said that, I had this argument with my Check Captain at my last simulator check. It was simply a Blue Hyd Failure and I took the Flap Full VLS out of the MCDU and added the correction, entered it in the FMGC and then selected Flap 3. He said that I must ALWAY's work out the V APP from the QRH and had no idea where I could have gotten the idea that taking it out of the MCDU was allowable. I told him that after flying the Airbus for 10 years I must have been mistaken on every other check and showed him the chapter in the Flight Crew Training Guide saying you could do this. He still wouldn't have it!!

In answer to the first question:

Vapp Calculation is the table to use for Abnormal / Emergency scenarios.

Vapp Determination is the table to use in Normal scenarios.

[Trust me Im Staff]

Hi Ollie,

Yeah it's funny how Training personnel get wrapped around the axle on this.

Couldn't be any simpler !

- T

[mcdhu]

But what you have to realise is that the Vref on the Perf App page is for your destination which might be 12 hours away!

So, activate the approach first, add the delta Vref to the newly calculated Vref, insert, and then select the F3 prompt for landing on the same page - and on the GPWS panel.

Cheers,
mcdhu

[Trust me Im Staff]

Mcdhu ... I believe I indicated that in my post. ;)

[mcdhu]

Trusty.....you did indeed. I was merely trying to make it absolutely clear to those less experienced than you (and me!). This aspect is often missed in the sim.

Cheers,
mcdhu

[Superpilot]

From my own notes and in line with the new FCOM/QRH:

Approach speed corrections and landing distance factors:
(Use with an ECAM message LANDING DISTANCE PROC… APPLY)

1.) From QRH ABN-80.16, (Dry) or 80.7 or 80.18 (Wet or Contam.) and if Landing Distance Summary table not available (otherwise everything should be on QRH page with the failure), obtain a.) Flaps Position, b.) ∆VREF, c.) LDG DIST Factor

2.) To work out Landing Distance, obtain distance from QRH FPE-IFL 2/4 (Without Autobrake CONF FULL), multiply by LDG DIST Factor and any additional factors (1.1 or 1.2, Anti Ice, A/T) from Vapp table (in 3)

3.) Using Vapp Calculation table, QRH ABN-80.14, obtain APPR CORR (VREF = VLS in CONF Full from Perf page)

4.) Insert Vapp into Perf page, and only after this select CONF 3 on Perf page. However, be careful. For any subsequent failures requiring the same procedure to be repeated, you must revert to CONF FULL on Perf page before entering new Vapp speed, then select CONF 3 again.


I would like to hear from others if this approach is wrong or long winded. Thanks

[Natstrackalpha]

I would like to hear from others if this approach is wrong or long winded. ThanksSuperpilot.

It is neither wrong nor long winded, as is, exactly as you say..

.

[mcdhu]

Superpilot - spot on. But to take it a little further, we now need to decide what to do with the landing distance we have come up with.

Let's take a 66T A320 with GRN+YLO failure on a dry, still 26L at LGW (LDA 2831m)

By my reckoning, you need 910 x 2.8 = 2548m. Loads of room - provided you get everything absolutely spot on with the landing. But we are advised to add a factor of 15% which takes the figure up to 2930m - oops!

If you are lucky enough to have the benefit of the new FOVE, you can extract an OLD which should come out roughly the same as our increased figure.

Food for thought.
Cheers,
mcdhu

[Mike Rosewhich]

SP,

Why do you select CONF 3 in the MCDU after inserting a VApp? I can't see the reason but am willing to be enlightened.

[mcdhu]

So that the ECAM Landing Memo knows that you are going to land with the Flap Lever in 3 and won't ask for Full.

mcdhu

[Natstrackalpha]

. added aaaaaageeees later . . y`know, it is easy to work out your landing distances corrections going through the manual and/or QRH, but it is confusing to look up a Full configuration figure (which would imply loadsa lift and slower airspeed, and, and, therefore less runway or should I say LDR)) for a Config Full setting.

If the process was (AND IT IS NOT) to calc config 3 for Full then that would be logical - because you are going for a lesser performance landing 3 = faster, but less flaps, more runway to a slower, more lift, less runway configuration.

In short - do we do it this way? Calculate Config Full and then do it in Config 3? Yes.

Do we know why? Nope

but, do I know why? nope.

So, does anyone know why . . . ? pprune hmm?

Also, (completely unrelated) - some say, to look atthe ECAm warning- go to the QRH, check for exceptional . .thang and then proced with . . ECAM actions.,
. Maybe, we could do the ECAM actions and then do the exceptional thingymebob out of the QRH.
Also - ECAMs prior to T/O - if they have not been inhibited, then you are stuck with having to do it - especielly if it says something interesting like "do not TakeOff"

More stuff is not going to kill you than IS going to kill you - so at the end of the day, use your commonsense - not just ECAM procedures and or referring to the QRH but the commonsense bit, look at the aeroplane as an aeroplane and you may be able to fly it -

.all this is the price we pay for being pilots and yet taking over the duties of the Flight Engineer, which we are not, the mentality is slightly different. One cares that it works properly and the other cares only that it gets you home in one piece, this time around.

[Checkboard]

The corrections in the table for speed and landing distance are based on the same simple base reference, to keep the calculation as similar as possible for each different failure.

Those base references are: VLS CONFIG FULL for speed, and Landing distance dry, without autobrake, CONFIG FULL for distance.

So you start with those basic references, regardless of the failure, then build on your various corrections to get to your actual condition for your particular landing.

[737Jock]

The corrections you apply take account of the flap setting to be used, even if the only option is to land conf 3.
However to clarify; some failures give you the choice of landing in flap full or conf 3, for example AC BUS 1 failure:

Conf 3: delta vref = 6 and land dist factor = 1,3 (dry no rev)
FULL: delta vref = - and land dist factor = 1,2 (dry no rev)

As you can see for the same failure the corrections to be applied are different based on the landing configuration. It is clear however that Conf 3 will give a higher Vapp and greater landing distance compared to FULL.
So the correction factors take into account the landing config and that is why you always use vref FULL and landing distance FULL as the basis.

Also the comments regarding more lift for flap full vs conf 3 are wrong. Very simply stated the lift is equal to the weight of the aircraft.
Flaps and slats generate the ability to fly at a lower speed while generating the same amount of lift, lowering the noseattitude of the aircraft (for visibility), reducing VS and producing drag. The change from Conf 3 to FULL is more about drag then lift or VS. Just look at the minor change in VLS, compared to going from clean to Conf 1 (slats only).