777 RNAV approach issue - help

[James Bennett 52]

I was doing a flight from London to Hong Kong in the 777f yesterday and decided to try an RNAV approach instead of an ILS. Not sure where I went wrong but on the RNAV-z RWY 25L approach once I entered the HOLD at GUAVA I could not exit it. I went on the HOLD page of the FMC and pressed the LSK for exit hold, but the EXEC light never lit up and the FMC wouldn't let me exit the hold even if I tried line selecting and copying the next way point over the hold on the LEGS page.

 

Some other weird stuff happened right after; I couldn't modify the route at all in the FMC. Even trying to select the ILS approach in the arrivals page didn't change the route plan. I had to go around as I was trying to hand fly the approach and work out what was going wrong and upon pressing the TOGA button the FMC just went dead and wouldn't let me change anything related to the route. It didn't even come up with any of the FMC error messages it just didn't respond to any changes I wanted to make other than to allow me to cycle pages and copy stuff to the scratchpad.

 

Where did I go wrong?

 

This "glitchy" behaviour doesn't occur shooting an ILS programmed approach however I have had issues with the TOGA button in flight before (does always work on takeoff but on the rare few occasions I've used it to go around it has bugged out).

[777simmer 117]

Sounds like an fmc nav database error locking up the fmc.

 

Even if you had done something wrong as far as the rnav approach goes, it should not bug up the fmc.

 

I suggest you try an rnav approach at another location.

[serviceceiling 135]

In this case, don't become a "slave to the FMS" , step down one automation level and revert back to V/S and HDG SEL.

But yeah as Rob said, check your navdata and maybe consider a clean re-install of the 777 to rule out any installation errors. 

[James Bennett 52]

Thanks guys. Any way I go about rebuilding the nav database? I'm using AIRAC 1404 through navigraphs desktop program.

 

Bogdan, you're right ordinarily I'd just ditch the FMC and fly the thing but the holding stack is only 6nm from the runway and the flight director had taken the plane significantly off course so a go around was needed. I only kept playing with the FMC after that through curiosity over what had went wrong.

[scandinavian13 5,192]

 

 

Thanks guys. Any way I go about rebuilding the nav database? I'm using AIRAC 1404 through navigraphs desktop program.

 

Navigraph's tool has a built in function to restore the prior version. I don't recall specifically how to get to it, but it should be pretty easy to find.

 

If you can find a way to repeat this reliably, go ahead and submit a ticket. Worth looking into on someone's end.

[James Bennett 52]

Navigraph's tool has a built in function to restore the prior version. I don't recall specifically how to get to it, but it should be pretty easy to find.

 

If you can find a way to repeat this reliably, go ahead and submit a ticket. Worth looking into on someone's end.

 

If it happens again, i'll submit a ticket. For what it's worth I just realised i'd missed SP1c so i installed that and haven't flown yet; but i don't think that would change anything as this isn't a published bug they've fixed (i suspect it's down to my end).

[downscc 1,327]

IMHO I don't think navdata can cause any of the behavior you described; however, current cycle is 1413 rev3. When the FMS detects corrupt data it should give an error message and simply ignore the data.  I think there was something amiss at the hold that you were unable to escape from, but a locked up CDU is unusual. I had that happen once during testing and was never able to reproduce it, and I have not had it happen since then. Perhaps SP1C is the solution.  Please do submit the problem via trouble ticket if you can reproduce it.

 

I started using the Navigraph FMS Data Manager application after adding PFPX and Topcat because they also use navdata. The free application checks for updates and installs them leaving me free to do other things with my time.  Nice tool.

[James Bennett 52]

IMHO I don't think navdata can cause any of the behavior you described; however, current cycle is 1413 rev3. When the FMS detects corrupt data it should give an error message and simply ignore the data.  I think there was something amiss at the hold that you were unable to escape from, but a locked up CDU is unusual. I had that happen once during testing and was never able to reproduce it, and I have not had it happen since then. Perhaps SP1C is the solution.  Please do submit the problem via trouble ticket if you can reproduce it.

 

I started using the Navigraph FMS Data Manager application after adding PFPX and Topcat because they also use navdata. The free application checks for updates and installs them leaving me free to do other things with my time.  Nice tool.

 

I may simply repeat the flight itself as i'd quite like to see if it does re-materialise. Certainly was no error message, the FMC just went weird and everything else continued as normal... very strange. Will submit a ticket if it repeats.

[777simmer 117]

IMHO I don't think navdata can cause any of the behavior you described.

I agree weird and should not happen.....and I could be mistaken and mixing things up, but I thought there where quite a few post of people with database problems leading to FMC lockups or other problems.