GNS-XLS FMS Updating

[TSandPSintheGREEN]

Hi

Wondered if anyone could help with this. WE were positioning on 31 July from A to B leaving at 1600Z, then due out of B towards C at around 1900Z. The FMS did nothing unexpected on the first leg, but decided to update itself before we could launch for the second leg. Is this to do with the fact that it was the last day of the month and now past 1800z ?

Most incovenient with pax loaded etc... seemed no way round it, and only just caught the slot, with 1 minute to spare.

All help welcome on this one

Ta

TPG

[kijangnim]

Greetings
As far as Airbus types are concerned :
The FMS doesnt perform a NavDB update on its own, it has to be done by "someone" ON THE GROUND, Aircraft stopped, parkbrake set, doneflight phase or preflight phase.
There are NO INHIBITION preventing you to do it in flight, however if you do it, you will simply loose everything, such as autopilot, autothrotlle and Both FMS, not a very pleasant situation.

[dusk2dawn]

What do you mean by "FMS decided to update itself..." ?
What happend?

[TSandPSintheGREEN]

Hi

Thanks for the interest. A new disk with the new database on valid up to end August had been loaded in physically some six days previously. Usually the next ON cycle of the GNS-XLS will start with a message saying "Database update - please wait" This hadn't happened up until the time described above, despite there being around five sectors flown, presumably on the old database, before the FMS "decided" that it was time to pull the new data from the fresh disk into it's memory... Being the last day of the month we surmised that this might be the reason?

Thanks for any further thoughts on this
Cheers

TPG

[ahramin]

What aircraft is this? All of the GNS-Xls FMSs that I have seen will give you the option to load the database on startup if there is a database update card in the slot. Press line select key 1 to update, or 2 to skip update.

When was the new navdata effective? Last update in N America was 15 July so the end of the month would mean nothing.

Perhaps the wrong button got pushed?

[TSandPSintheGREEN]

IN a C525, which button could be pushed to cause a problem then? We tried the skip option and it kept going back to the options page only...

[ahramin]

Sorry, it's not a skip option. Line Select 2 would have been RESTART NAV, which will bring you back to the same page unless you remove the disk.

I don't understand how the FMS would have started the update unless Line Select 1 (BEGIN UPDATE) was pushed. Maybe a case of "That button didn't work, lets try the other one?"

If the navdata in the disk became current in between your flights, that might explain why the unit chose this particular time to display the update page but to my knowledge the page will be displayed any time a card or disk is loaded.

Call Honeywell, let us know what they say.

[Capn Bloggs]

Some background that may explain why it changed when it did: new databases are current on the AIRAC date (always a Thursday) and time. For the last cycle, that was 30 July at 0000UTC. I'm not familiar with your aircraft, but our GNS/CDU XLSs (in the 146 change) automatically then, regardless of where you are in the world. No operator input to force the change is possible. This didn't have a major impact on the 146 as the "FMS" wasn't really an FMS, except that here the local procedure is to use the new DB after 1600UTC the day before, as that's when there is no activity in the air. Everybody's asleep.

By the way, databases are not "month by month". They run on the 28 day AIRAC cycle.

As far as Airbus types are concerned :
The FMS doesnt perform a NavDB update on its own, it has to be done by "someone" ON THE GROUND, Aircraft stopped, parkbrake set, doneflight phase or preflight phase.
There are NO INHIBITION preventing you to do it in flight, however if you do it, you will simply loose everything, such as autopilot, autothrotlle and Both FMS, not a very pleasant situation.
Sounds like a undesired "design feature" to me. In the 717, the DB cannot be changed after engine start.

[kijangnim]

Greetings,
It is not inhibited in flight, because, in the case of an inflight severe reset, the up-to-date Navdata base might have to be reselected. :ok:

[Capn Bloggs]

Fair enough, but STBY NAVRAD would still be available, I assume, and therefore access to the current database?