A320 Fmgc

[westinghouse]

hi all,

our 320 , 2000 series acfts have a new FMGC system which seems to have to added functions compared to the old one which sometimes donet work properly.

for eg. if you were to perform a vor aproach in selcted mode the AP will never intercept the final appraoch course. a message "no nav intercept" is displayed in the fmgc scrtach pad even if the flight plan is strung properly.

another one is at the gate when you try to access the INIT B page it keeps goind to the FUEL PREDICTION page.even after an FMGC reset it still doesnt acces the proper page.

do you guys have any suggestions to sort these rpoblems out.
thanx

[c680_pilot]

Probably there is a discontinuity in your flightplan ? If so, the bus will continue on the present heading after overflying the last fix and will never intercept the approach. When on radar vectors, you can also use the extended centerline and arm NAV to intercept the final (what it will do automatically after selecting the extended centerline).

Init B is only accessible as long as the engines are not running.


Maybe it helps,

best regards

[TyroPicard]

if you were to perform a vor aproach in selcted mode the AP will never intercept the final appraoch course
This is always true in selected mode - have you left out a key ingredient from your question?

[Airbus Girl]

That is excactly what I was thinking!!

[Metro man]

We have two different versions in our fleet THALES and HONEYWELL I think. Some differences eg one allows INIT A page after engine start, one requires heading to be selected before activating secondary flight plan, one puts all changes into the temporary flight plan and requires you to confirm where as one takes the changes straight away, differences in how to change the alternate in flight etc

Have a look at FCOM 4, it may just be a difference rather than a problem.

[westinghouse]

oops sorry my mistake.:O

what i mean was when your being radar vectored for the VOR app final intercept on arming the approach the acft does not intercept the final track.
i have checkd the flight plan several times and it is sequenced correctly.

as for the init B page this problems occurs before engine start at the gate.

[Dani]

I rather suspect that your company changed to the Pegasus FMGC from Honeywell. It is in fact a little different.

Does it give you prompt before executing a direct?
Can you do abeam fixes?

Not to follow a radial in selected mode is a good thing, you have to arm it!

I guess you mean a 320-200 series.

Dani

[westinghouse]

yep. your correct Dani.
it has all these functions which are not available on the old 320's.

is not inetcepting the final track a common occurence on this new fmgc?

[Dani]

Thanks for the clarification.

Please confirm: You have the interception prediction on your ND, your NAV is armed (on the FMP) and it does not intercept?

Then there would clearly be something wrong. I haven't wittnessed this at any time. Did you intercept the inbound radial on your selected HDG? Maybe you selected the wrong inbound radial (radial instead of track, 180 degrees different)?

Dani

[Blinkz]

Theres a little bit of confusion here. Are you trying to do selected or Managed NPA? If the app pushbutton has been pressed then the Appr Nav should be the armed mode on the FMA, and once it calculates the intercept should become the active mode. However if you are doing a selected NPA then this should not be used?

As has been said I've never had it not intercept when on a correct heading with Nav being armed.

[westinghouse]

ok lets start from the begining.

im doing a fully managed ( vertical and laterally managed) VOR approach.

how ever ive been issued radar vectors and ive been given hdg by the controller and this hdg will be intercept the final track.

the flight plan has been sequenced properly.

the app p/b is depressed and it shows "final" in blue etc. on the PFD

once getting closer to the radial a message comes up on the MCDU saying "NO NAV INTERCEPT"

the acft then passes through the final intercept radial and continues on the hdg set for the intercept.

ive tried this approach abt 3 times and it always seem to be the same and i end up doing a sleected approach in the end.

ive tried this on another 320 of ours with the same results.
the older 320 we have has no issue with this vor appraoch and completes the fully managed app perfectly.
if the older one can do it why cant the newer one?

thanx guys. i appreicate the attention your giving to this.

[Airbus Girl]

OK, I am confused. If you are in heading (actually should be TRK mode) then you are using a selected mode. Therefore are you saying that you have pressed the HDG button in an attempt to arm the NAV mode and get it back onto the managed approach? If I was in TRK (or HDG) selected mode then I would be expecting to undertake a selected approach rather than managed. Unless its miles out and you then select "DIR" to the relevant point on the approach.

Confused....

[toby320]

OK, in that scenario my only guess is that you are missed your TO WAYPOINT and that could be the reason that you can not intercept :bored:

[ALK A343]

westinghouse,
I think you have to be within 1.5 NM of your Final fix for for the Approach Nav. or Final mode to engage when performing a managed non precision approach following radar vectors. If the vectors you are given do not take you into that zone Nav mode will not engage, however I do not know why it seems to work with the old Honeywell FMGCs as you described.
What you can do though, is to insert a direct to your final fix with the radial inbound function, when given radar vectors for a managed non precision approach. In this case the aircraft will always give you a nav intercept and approach nav and final will arm regardless of how far from the final fix your radar vector intercepts the final course. When inserting the DIR TO with RADIAL inbound remember to put the reciprocal of your final course. Hope this helps,
fly safe!

[Blinkz]

As ALK has suggested, extending the centerline from the FAF will usually solve any sequencing problems, and is the easiest way to make sure that when on an intercept heading Final Nav becomes active.

[FlightDetent]

I cannot find the message you reference in our FCOM. The books are for Honeywell Legacy (old) and Pegasus (new), also Pegasus 2+. Thales being the third option, is it possible to check your FCOM 4 MCDU messages list (4.03.30 or so) to find out the conditions under which "no nav intercept" would be displayed?

Having FUEL PRED displayed in response to INIT B request sounds like an irregularity to me, but I have no experience with Thales.

Yours,
FD (the un-real)

[moredrag]

if you have sequenced it and havent extended the centreline then you'll need to erase PPOS in Line select 1 left in order to arm nav to intercept.

[Stratobus]

I am confused! only aircraft wwith VOR LOCK will intercept a VOR, if you are on vectors for a VOR approach you use TRK/FPA, pressing approach wont work unless it's an ILS! selecting NAV would intercept the inbound crs selected in the RAD NAV page if the flt plan was correctly sequenced.. or am I missing the point here?

[Blinkz]

Stratobus,
The App pb can be used for NPAs, but only for a fully managed NPA. In this case the aircraft isn't actually tracking the VOR or NDB but using the Managed modes and the aircraft database as reference for the approach. Obviously the pilots need to back it up with the navaids as well.

[Tail-take-off]

another one is at the gate when you try to access the INIT B page it keeps goind to the FUEL PREDICTION page.even after an FMGC reset it still doesnt acces the proper page.

Experienced this myself the other day with fmgc2. Likewise multiple resets didn't cure the problem. We swapped the navdatabases over to dump all the flightplan data & started from scratch.

If this doesn't work try deleting the secondary flight plan then go through sec-init & rebuild the whole lot in the secondary (inculding the parts in init-B) then activate it.