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A320: PPOS

Old 4th Sep 2012, 19:17
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A320: PPOS

Quick question for A320 skippers. When we are in the vicinity of the airport being radar vectored, I have CAs asking me to not delete PPOS until on the other side of the missed approach procedure. They claim if we were to remove it, it could sequence the flight plan to the missed approach procedure. I, personally, delete it every time and I have never seen it do that. I assume it was on the older A320s with the old software. As anyone encounter this? If yes, what are the parameters that makes the flight sequence to the missed approach procedure? As the software been updated to prevent this?
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Old 4th Sep 2012, 20:20
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If you delete the PPOS then the flight plan will sequence one waypoint up. Whilst I can't see it being an issue for a missed approach it very well might muck things up if you are doing an RNAV or managed NPA. Its best to extend the centre-line from centre fix waypoint/start of descent once you are under radar vectors so that the flightplan is all correctly sequenced.

Last edited by Blinkz; 4th Sep 2012 at 20:22.
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Old 4th Sep 2012, 21:16
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This can cause problems, if you have the a PPOS followed by the final fix for the runway, if you delete the PPOS then the flightplan will sequence to the runway threshold. That is fine unless you then are vectored past the runway threshold within 7nm. If this happens then you will potentially lose the entire flight plan as the FMGC thenks you have landed.

At my previous airline it was policy not to delete the PPOS until you were on the final intercept. At my current airline when flying a visual circuit you don't take the PPOS out at all due to the above problem.
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Old 4th Sep 2012, 22:54
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Why don't you just extend the centerline from the FAF? This will allow the FMGS to auto-sequence on the approach.
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Old 5th Sep 2012, 01:41
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737Jock has the correct answer. It will allow the flight plan to sequence correctly but more importantly ensure that the missed approach is available should you need it.
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Old 5th Sep 2012, 01:47
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lose the entire flight plan as the FMGC thenks you have landed.
Are you sure about that? Sequencing the missed approach seems more likely.
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Old 5th Sep 2012, 01:47
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Don't ask me, you would have to talk to the bloke who rights our SOP's for that answer. I have no problem doing it either way, I have never been a big fan of extending the center line as I find it just as easy to leave the plan with the PPOS in it. On the other hand I am quite happy to extend the center line for the FO if that is the way he/she prefers to do it (just not the recommended way by my airlines SOP's.

As for the sequencing, yep I am pretty sure that the only way to activate the missed approach into the plan is by selected TOGA with atleast flap 1 selected. If you fly past the rwy threshold within 7nm and it is the active way point the flight plan will disappear and the missed approach won't be available in the FMGC.

The training guide recommends either using the extended centerline technique or manually deleting the appropriate waypoints in the plan. If the next way point under the PPOS is the one you are going to fly over then just leave well alone as when you fly over it the plan will sequence anyway and the PPOS will disappear, no need to manually delete it.

Last edited by Ollie Onion; 5th Sep 2012 at 02:08.
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Old 5th Sep 2012, 08:28
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Can't extend the centre line on all FMGS version - I think 2 of our aircraft have that capability, none of the others do.

As others have said - its a matter of sequencing the flight plan and confusing the computer as to where it thinks you are.
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Old 5th Sep 2012, 15:23
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Most important thing when Flightplan is sequenced is to have a relevant TO waypoint on top of ND. I have seen many pilots sequencing the flightplan by just erasing and erasing in an erratic way...Until a nice centerline appears on the screen , not taking into account the TO waypoint on top of ND.This is poor situation awarenes

So if you have PPOS-CI04L-MD24-LFMN04L. It means that PPOS is your FROM and CI04L your TO waypoint.

By erasing PPOS, CI04L becomes the FROM and MD24 becomes the TO. By doing that you might just erase the FAF (where it shows -3)

And if you have no intermediate point like PPOS-CI04L-LFMN04L by erasing PPOS you will make CI04L as FROM and LFMN04L as TO. For ILS it s not really a problem, although I d like to have something proper on MCDU but as previously stated for NPA managed , you will be surprised!

So extendend centerline is nice but having the relevant TO in the second line of your FMGS and on TOP of your ND is more important.

Last edited by Citation2; 5th Sep 2012 at 15:24.
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Old 5th Sep 2012, 21:32
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There is no problem with deleting the PPOS and having the FAP as the FROM waypoint. I do it on most on my flights, and it works out just fine.
Once you pass the marker/intermediate fix the runway will be TO, and the marker/intermediate fix the FROM waypoint, and everything is as it should be.
And yes, even RNAV approaches can be flown like that, the Airbus intercepts those even before the FAF.
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Old 6th Sep 2012, 07:29
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If you have the F-Pln sequenced as 737jock states and fly a downwind leg within 5nm of the FAT, the flightplan will sequence to the missed app. If there is no chance of you doing this then no problem, if there is then you have an issue. PPOS won't actually stop this happening...

(We have this issue routinely at LHR - Its a bum when you are on an RNAV approach!)

If I anticipate this happening, I leave a hold active whilst flying downwind. Once past the FAF, then I extend the centreline...

This is with FMS 2+...

Last edited by Cough; 6th Sep 2012 at 08:02.
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Old 6th Sep 2012, 20:54
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Or, once you're under radar vectors copy the active into the secondary. That way if it dumps (or you do an discontinued approach without selecting TOGA and it dumps as you pass the threshold), you just activate the secondary and you've got your final approach plan back with all landing PERF as well
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Old 7th Sep 2012, 22:25
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Please refer to your books and do not invent procedures. We are talking about aviation and not potatoes buisness.

Nothing will happen if the FAF becomes the FROM waypoint? How can you say that? Not 100% true, depending on the type of approach , Which automation you are using and from where you are being radar vectored.

Quick reminder FCB-FCB23 P 6/8

CAUTION : "Before arming NAV, check that the correct "TO" waypoint is displayed on the ND. ‐ The intercept path in HDG/TRK must not cause premature sequencing of the FAF. The FAF should be sequenced in NAV mode, when established on the final approach course."

Another reminder from FCOM GEN P 10/34

Definition of CAUTION: "An operating procedure, technique, etc. that may result in damage to equipment if not followed."

Another one that could help...

FCTM:NO-110 P 2/8 : "A good cue to monitor the proper F-PLN sequencing is the TO waypoint on the upper right side of the ND, which should remain meaningful. If under radar vectors and automatic waypoint sequencing does not occur, the F-PLN will be sequenced by either using the DIR TO RADIAL IN function or by deleting the FROM WPT on the F-PLN page until the next likely WPT to be over flown is displayed as the TO WPT on the ND."

I would like to add this one

FCOM PRO-NOR-SOP-19 P 15/20: "Check correct TO waypoint on the ND"

Obviously the aircraft will not fall from the sky just because you wrongly sequenced a waypoint. Also you could say that nothing will happen if you switch off the MCDU and nothing will happen if you activate approach phase in cruise and fly selected 0.78 . But why would you want to do things upside down? Instead of doing a documented procedure like a professional?
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Old 8th Sep 2012, 05:47
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if you want to use the secondary flight plan it has to be off sequence. other wise it will sequence de destination just as the primary flight plan.
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Old 8th Sep 2012, 09:35
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Correct, Citation2. The easiest way to do that is to have a waypoint on the extended centerline before the FAF. That way the FAF will be th TO waypoint until sequenced.
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Old 8th Sep 2012, 16:55
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MD83FO is correct about the secondary - Seen it sequence too when flying downwind under vectors within 5nm of the FAT when its a straight copy of the primary F-PLN.

I have to say I do what safelife says on an ILS approach. On an rnav or managed non-precision approach where the approach is steeper than standard this technique could leave you below the level of the FAF. Not somewhere I want to be...
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Old 9th Sep 2012, 20:18
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SEC PLN sequencing.

Interesting.... I've never seen the secondary sequence. Why would it? It's not the active plan. We routinely copy the active into the secondary for the cruise and that doesn't sequence as you fly from waypoint to waypoint - totally "on plan".

Is this FMS 2 and the more up to date FMGC you're talking about?
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