A-320 VAPP determination with failure and landing distance

[Magnetic Iron]

How do you like the changes in the Airbus QRH, landing distance and specifically a Blue and Yellow HYD failure ?

Does anyone have any info ( links ) on the best way to calculate the new VAPP and proper sequence to calculate the landing distance and app. As Airbus taught it a specific way and now they changed it, as per the global changes and new regs.

I personally liked the QRH summary for blue and yellow and how it gave Vapp and landing distance info right on the summary.

The caution calculating Vapp means that there´s is a possiblity of making an error and incrementing too much speed. has anyone been caught in the trap ?

APPR COR and then landing distance speed correction, all this when you have a dual hydraulic failure, surely they could have simplified it more, or is it easy for you all ?

Thanks for your help and input.

[Oceanic815Pilot]

Personally I don't care for the new QRH procedure.

Airbus claimed the previous procedure summary for the dual hydraulics and others kept you from having to reference any other QRH procedure but that wasn't the case. You still had to reference the "Landing with slats/flaps jammed" procedure for the green/blue or green/yellow failures to obtain your max speed for a go around.

With the new procedure the summary is absolutely worthless as you now have to determine the landing distances yourself in addition to the other procedures you need to reference and fine tune the Vapp calculation as before.

From my recent experience in the simulator I didn't find any information
within the summary procedure that
isn't on the ECAM or one of the other procedures that you need to complete.

As you mentioned the chance you will make a calculation error has been increased. It was suggested to me if you are landing on a dry, long runway then save yourself the trouble and do a ballpark calculation and call it good. If you have the time or conditions are marginal than do the full calculation or use the LPC if your company has one.

When we compared a manual calculation per the QRH with the LPC we found the QRH distance calculation to be a factored distance with the additional 15% added.

Any other observations and opinions from the bus drivers?

[Magnetic Iron]

Thanks Ocean,

Totally agree,

Mi opinion is the old summary was better

[PT6A]

ADM,

The last information I had from a QR pilot was that they were not allowed to use the LPC in the event of failures, this was prior to the Airbus changes.

I would be curious to know if the software from LIDO LIDO/Takeoff provides a more sensible method to the calculations.

The way this has been introduced, I agree is far from satisfactory.

[Alexander de Meerkat]

Apologies PT6A - I have just removed my previous post for editing as you put-in a reply. Hence my new version is below yours! Previously we leaned towards the QRH for landing distance calculations but with the latest software we now use the LPC for multiple failure cases.

I work for easyJet where we have recently introduced a modified landing distance calculation method in both the QRH and the LPC (Less Paper Cockpit - fancy laptop with a software module on it). In all honesty the introduction of it has been less than ideal, and many people have been left confused. However, given the limitations of the process, it is still an improvement on previous mechanisms once you get the hang of it. I am not sure if the LPC the Qatar guys use is the same as ours, but I imagine it is. The key thing to remember is that the QRH is only of any value if you are dealing with simple single failures. If you face multiple failures then you must use the LPC, and that is where the problems begin. Having now given a great deal of thought to the matter and discussed it at great length with other members of the Training Department and people who I consider 'informed' on the issue, I think I have now finally got my head around the issue.

There are however, IMHO, significant limitations with the current LPC software that must be understood before you can safely use it. The first problem is where to consider ice accretion (not something our Qatar colleagues worry about too much I imagine, but a big issue in a European winter!). That is hidden in a drop down menu on the landing distance "anti-ice" menu - from memory it offers 'none', 'engine only', 'wing and engine' and finally 'ice accretion'.

The next problem is how to deal with failures and this is where a conceptual leap is required. The LPC always assumes a 15% landing distance margin plus the use of full reverse thrust on both engines - whether or not you have both engines available! That is a clear software glitch, but that is the way it is mechanised nonetheless. Therefore if you have a failure, you cannot just enter the failure using the F5 (Status) button and then going to an ECAM problem (ie L Eng Shut Down) as it still assumes full reverse thrust! It is theoretically possible to enter 'One Thrust Reverser' inop in the MEL, but if you try and use that with' L Eng Shut Down' on the in-flight failures for example, it will tell you it is an invalid combination. You have to select 'Both Thrust Reversers Inop' in order to obtain a valid calculation. In other words it is a thick system that requires you to make performance assumptions that are different from your actual situation. It is not very satisfactory, but workable once you know the limitations.

[PT6A]

No problem ADM,

Have you been able to get any feedback regarding the last issue? Ie basically having to trick the LPC so that the reverse thrust credit is correct?

I today read over the documents we got again, a 66 page .PDF and a PowerPoint presentation... Clear as mud springs to mind.

[Alexander de Meerkat]

Alas not - that is just the way it is unfortunately. Basically it is the collision of two different worlds - theoretical performance and real-world failures. The assumptions for theoretical performance are that the QRH assumes no thrust reversers and a non-factored landing distance. The LPC, however, assumes both thrust reversers are functioning at full reverse power every time and applies a 15% margin to the landing distance. The problem at the moment is that when you have, for example, an engine failure, it has no ability to then automatically recognise that there will be thrust reverse available on one engine only. The situation is further complicated by the fact that there is no calculation available for idle reverse thrust - it is all or nothing. That is not so bad if you use autobrake as they apply a deceleration rate which is modulated for thrust reverse - ie if you apply more thrust reverse the autobrakes will apply less braking power to maintain a certain predetermined deceleration. It is still not really very satisfactory and does not generate that warm fuzzy feeling we all want to feel knowing that the calculation is an accurate reflection of reality. It is, however, the best it can be and much better than the QRH. No doubt in time these problems will all be sorted but in the meantime it is important to understand the assumptions being made before relying on the calculations without thought.

[PT6A]

I see the post concerning this subject on "inside" from the 09/12/12 has gone unanswered.. It's really not great that this has not been addressed further.

Today I was speaking to a friend at another airline (not using the LPC) he asked his training department about the multiple failure case, apparently the answer from Airbus was that they need not consider multiple failures on this aircraft!:ugh:

[compressor stall]

Yep, that's what the fctm says almost word for word.

[tom775257]

<<apparently the answer from Airbus was that they need not consider multiple failures on this aircraft!>>

They consider multiple failures of the same ATA but not separate, they have said that on the very very rare occasions of failures from separate systems, the problems have been so severe that there would be no way of working out a useful landing distance anyway.

[RunSick]

Hi ADM
I have also been fidgeting around with the LPCNG. Could please tell me if you also have an "error" as result in Landing performance if: 1 brake INOP in the MEL + one ENG shutdown?

For me it doesn´t work and so far nobody has been able to give me any explanation on the issue.

I mean it is something that could happen any given day, yet the machine doesn´t take it. Am I doing something wrong? Skipping some part of the procedure?

Thanks for the reply.

[Alexander de Meerkat]

Hi RunSick. The basic problem is that theoretical performance in the LPC is only mechanised for two scenarios - no thrust reversers working at all or both thrust reversers working and generating max reverse. The scenario you discussed falls outside these two cases and it therefore rejects it as an invalid computation. Clearly it is unsatisfactory, but once you understand this limitation you just feed in the case which most clearly matches your situation (ie the one which gives the worst result to create a safety margin). I am not saying it is good, but it is vital to understand the system to make it work in the most safe sense for you. I hope that helps.

[RunSick]

Thanks a lot for that input. What a crappy system! Having a computer and not being able to "compute" something like that :ugh: