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-   -   A320 no speep entry on secondary (https://www.pprune.org/tech-log/408902-a320-no-speep-entry-secondary.html)

Firecock 14th Mar 2010 21:34

A320 no speep entry on secondary
Scenario: You have programmed the MCDU in the A320 from x to y. Now you decide to program the Secondary for the immediate return. Unfortunately you get the message “Flight Plan Full”. So you decide to create a Flight Plan from x to x. You enter the destination data but leave the performance on the secondary completely empty.

Question: What will happen after take off, when you activate the secondary? Will it copy the performance from the primary?

Remark: Please only post if you had a chance to try this in the Sim or with a link where to find this in the FCOM. I tried this a couple of times with a FMGS trainer but, the speed of the aircraft drops to 0 which I don’t think will actually happen in the aircraft.

Thank you very much for your help

Microburst2002 15th Mar 2010 10:02

So many things happen in that "trainer"...

Anyway, Why should the performance of y be copied for a return to x?

You have to enter the secondary performance, otherwise it will be blank and remain blank after secondary activation. The prompt ENTER APP DATA will appear in the MCDU.

Nubboy 15th Mar 2010 10:40

SOP's in my company is that the secondary is programmed for an early return to landing, normally your departure airfield.

Do I understand that you leave the Take off performance page on the secondary flight plan blank, but have filled in the airfield data for the landing?

If you decide to change flightplans BEFORE take off, then you now won't have any performance data for the take off. Best to pull over and think about what you want the nav kit to do before you decide to get airborne.

However, if you get airborne on the original primary flight plan, then it will have sequenced from take off to climb. Therefore if you need to return quickly, the landing data will still be in the secondary. Activate the secondary, activate the approach, and you should be all set up for a speedy return.

mcdhu 15th Mar 2010 10:55

I have never seen the 'Flt Pln Full' message in the A320. Perhaps it is a limitation of the FMGC training device.

To program for a return, change the secondary to your requirements and then hit 'Secondary Fpl' - Perf - 4 pushes on the 'Next Phase' prompt and fill in the s/w, temp, Qnh and MDA in the Perf Approach page.

tom775257 15th Mar 2010 11:12

I take it you are using the technique of copying the Fplan into the secondary and then lateral revision to change destination etc etc.

On older A320s with legacy FMS with a large flight plan in the primary, it will not be able to copy over the full flight plan into the secondary as well (when you try you get the Fplan full message). In this case build up the secondary from scratch, dont copy the primary into the secondary and modify. I have this, for example, flying an old A320 from Larnaca to Birmingham.

If you activate a secondary flight plan with nothing in it, there will be no performance copied over from the primary and the FMGC computed speeds on the MCDU will be based for the approach on the current FMGC gross weight not the estimated weight at landing. You would have to build up a flight plan and insert perf data.

Endeavour 15th Mar 2010 11:38

We use the OAA A320 simulator near LHR. The MCDUs are real, but although you would never know it, the FMGCs are actually a PC based emulation. The emulation is good, but as both the software and hardware are different from that used on a real A320. This set up should be treated with caution. If it works in the sim it may not work the same on the aircraft and vice versa.

To get around the OPs problem. If you cant copy the active flt plan (X to Y)into the secondary. Delete and then INIT the secondary instead with flt plan from X to X and complete the SEC PERF APPR page.

divinehover 15th Mar 2010 11:38

Just keep the Primary as a copy of the active. It's as much effort to change the Dest in the Primary as it is to activate the Secondary. Personally I would rather have a full copy of my Primary in case I need it. Either one takes less than 30 sec to accomplish so theres no point in complicating a simple procedure.

mcdhu 15th Mar 2010 18:48

But some of us have the EO SID in the secondary followed by the return which makes life much easier in the event of a big bang just after V1.

Microburst2002 15th Mar 2010 20:10

Either you fill in the approach performance in the secondary fpln before take off or you fill it once airborne and activaded if you have to return to the field.

Destination airport performance will not be copied in departure airport. That would be kind of weird.

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