A320 Nav system

[aanubis]

To all Airbus pilots,

I have a weird doubt regarding A320 navigation system.
As far as I know, it navigates using IRS, GPS (GPIRS) and FMS database calculating mix FM and GPIRS position.

Now if some how we lose the navigation database and GPS... and there's no map/nav display on ND ( I know it would be impossible to get into that situation ) how are we gonna naviagte ??

Do we revert back to finding directions using Jepessen charts and tuning nav aids ?? Or is there a workaround in this situation.

2. I assume the nav database in FMS is basically digital Jepessen charts.
So do we fly Great circle or rhumb line when we just plan using FMS ?

Please provide ur inputs to explain A320 navigation !!
Thanks in advance..!

[hetfield]

Try this. Old school....

[i_like_tea]

Ask for vectors..

Or get the Jepp airways charts out.

XXXXX Waypoint, on XXX airway, from the XXX VOR, Radial XXX at XX DME.... simples.

[Gulfstream757]

I wouldn't say that this couldn't happen look at Adam air flight 574 and yes they would revert to basic nav aids and atc vertors

[i_like_tea]

Agree with the above.

Isn't it one of the more likely things to happen?
Dual FMGC failure for example.

[aanubis]

Thanks for replies...

In case of dual FMGC failure, dont we have a back up navigation feature which will show the saved flight plan .. ???

[HPbleed]

Um yes, the PLOG shows the flight plan.... but if both computers fail it's not going to be able to show you the routing on the ND. You're down to backup NAV if that's what you mean - which allows you to tune navaids through the Comm boxes. Ask for Vectors or direct VOR/NDBs so you can fly direct to something you can tune.

[I-2021]

Hi aanubis,

Do we revert back to finding directions using Jepessen charts and tuning nav aids ?? Or is there a workaround in this situation.

Like others have said, use raw data navaid tuning, ask for vectors, follow the highway If you have a dual FMGC failure that's how you will end up.

In case of dual FMGC failure, dont we have a back up navigation feature which will show the saved flight plan .. ???

Depends on your FMGS version and software. Basically you need a memory card with enough memory to constantly save and back-up your flight plan. Some have it, some don't. On the 330/340 it is a standard feature.

2. I assume the nav database in FMS is basically digital Jepessen charts.
So do we fly Great circle or rhumb line when we just plan using FMS ?

It could be a great circle, depends on the segment that you are flying. The FMGS will follow the routing that you insert, which is usually as close as possible to a great circle as per your flight plan. This is not always the case anyway because you may plan minimum flight time routings that take advantage of strong tailwinds that are not necessarily great circle segments.

Cheers.

[Fastwolf]

Also, on newer airbuses, in case of dual FMGC failure, we have a "Nav Backup" that basically uses the IRS (ADIRUs) to keep your flight plan, waypoints, etc. It permits to continue the route, and basic management. Better than simple raw data. Of course for the approach itself you should use navaids on raw data.

Not usable in case of dual MCDU failure, however.

Regards

[aanubis]

Thanks Fastwolf for that input...
I-2021 : Thumbs up for clarifying

[Dan Winterland]

You can tune the VORs/ILSs and NDBs throught the standby NAV funtion on the Radio Management Panels. Information is then dispalayed on the DDRMI assuming your aircfaft has one fitted - newer airframes may not.