PMDG 777 false terrain alarm

[Brett503 0]

I am getting the same problem, two airports I recall is OMDB and EGLL.

 

The terrain warning kicks off at about 1000ft AGL and accompanies down till I'm about 10ft above the ground. I also have missing callouts like 500, 400 but I do get "2500" and "10" callout. I always have Flaps 30, speedbrakes armed and autobrakes at 3 on both airports. I also have VREF + 5 speed and I normally disengage AP at 1000ft. I will provide a screenshot if I can. I use AIRAC 1501.

[Brett503 0]

http://i.imgur.com/anDLsDY.jpg

http://i.imgur.com/anDLsDY.jpg

 

Here is a picture, as you can see, it is in a landing config

[cathay747 0]

does anyone have any suggestions?

[cathay747 0]

just heard that AIRAC cycle 1503 is released, will that solve the issue?

[777simmer 117]

An AIRAC is a navigation database.

An update would update airways, SID and STAR, so that the things you can select from your FMC are identical to the real world paper charts.

 

It does not update the terrain database.

 

FSX terrain can be updated to reflect real world terrain better with addon like FSGenesis mesh (there are other products for mesh too but I use FSGenesis).

Updating FSX mesh (terrain) is nice but will not fix your problem.

 

Because the PMDG777 terrain database (which is what gives you the warning when close to terrain) can not be updated as far as I know.

 

False terrain warnings could occur if you are descending towards an airport that the terrain database does not have.....but OMDB and EGLL will surely be in the database.....so I dont know what causes your false warning.

Maybe your PMDG777 terrain database was corrupted and needs to be restored?

[Mike777 163]

Just saw this thread.  A few points and suggestions:

 

The file WpNavApt.txt has entries for each airport runway.  It is updated as part of each new Airac.  The last 5 digits of each runway entry are the altitude for that runway.  For example KATL is 01026. 

 

The file ARPT_RWY.dat, also in the PMDG/NAVDATA folder, is NOT part of an Airac (take a look at the first line, and compare it to Airac files).  It is generated by the PMDG 777 and used, AFAIK, as a kind of cache.  It also has entries for every airport and runway.  At the end of the first line of each airport entry is an altitude number (following the last semicolon).  For each runway, the fifth field in (marked by semi-colons) is the altitude for that runway.  Here is KDEN RW 7, 5434 is the runway's altitude:

 

RW;07;39.840945;-104.726656;5434;11155;082;082;12000

 

So, would those people who are having a problem please take a look at the entries in the above two files for the problem airports to see if the altitude is incorrect?  All these files can be opened and searched w/ Notepad.  Just don't edit or save them!  This would help narrow down the issue.  Please report back.

 

Also want to mention that Airports.dat is part of the Airac, but only has longitude/latitude for each airport, no altitude data.

 

If ARPT_RWY.dat has an altitude error, please note it and then remove that file from PMDG/NAVDATA.  It will regenerate the next time you load the 777.  See if that fixes the problem and report back.  This procedure is known to fix other errors having to do w/ runways not showing up in the FMC.

 

Finally, as another clue, I have only noticed "Pull Up!" when approaching Kai Tak runway 13.  I approach on the glideslope, but when I make the turn it becomes a visual landing and I may or may not still be on the glideslope (and am definitely not on the loccalizer!).  It's after the turn as I approach the runway that I get the warning.

 

Hope this helps!

 

Mike

 

 

[Mike777 163]

Members

40 posts

Joined 5 Months and 4 Days Ago.

 

Posted 04 February 2015 - 02:53 AM

I was landing at LHR with the 777-300ER the other day, and when I was locked and coming down the glideslope, at about 1000ft, the terrain alarm screamed all the way until I touched down on 27R, despite I was in full landing configuration (flaps 30, gear down, autobrakes 1)

scenery : UK2000 London extreme

 

OK, I've been able to reproduce the problem.  I changed the altitudes for all runways at KSFO to 1013 instead of 13 in both wpnavapt.dat and ARPT_RWY.dat (altitude data as described in my previous post).  I loaded a previously saved, often used 28R approach situation using the 200LR (in Steam - @ 6 mi out), and got "Caution terrain" all the way down the GS until @ 200 ft, when I got "Terrain, Terrain!  Pull UP!" w/ appropriate indications on the DUs.  

 

I deleted the ARPT_RWY.dat file and let it rebuild.  It picked up the incorrect 1013 altitudes, presumably from WPNavApt.txt.  Same warning result.

 

I fixed the data in wPNavApt.txt, deleted ARPT_RWY.dat and allowed it to rebuild, reloaded the same 28R approach, and no more problems.

 

So the next time this happens, check the altitude entries for the problem airport in WPNavApt.txt and see if they are wrong (as I described earlier).  If not, delete ARPT_RWY.dat and allow it to rebuild.  See if that fixes the problem.

 

It's still not clear if the problem is coming from the Airac data, presumably in WPNavApt.txt, or the PMDG 777 cache file, ARPT_RWY.dat. So I hope people w/ this issue will report back on what fixes it.

 

Mike

[cathay747 0]

ok so for vhhh07L it says 12467 in my wpnavapt

what do the numbers represent? feet? Any decimal places involved??

[kevinh 409]

ok so for vhhh07L it says 12467 in my wpnavapt

what do the numbers represent? feet? Any decimal places involved??

That's runway length in feet. The figure for threshold elevation is at the very end of the line, last five digits IIRC. For VHHH it's 28 feet.

 

This data also appear in ARPT_RWY.dat. The elevation is after lat/long in that file.

[Mike777 163]

Also want to add that ARPT_RWY.dat has TWO entries for each runway, one presumably from the Airac/wpnavapt.txt file, and one apparently from FS's database.  So there could be an issue w/ either entry for a given runway, but I did not experiment w/ the runway entries that begin w "FS;".  But they both should be checked (also have to wonder if even a small discrepancy in altitude between the two runway entries causes problems).

 

Mike

[kevinh 409]

Also want to add that ARPT_RWY.dat has TWO entries for each runway, one presumably from the Airac/wpnavapt.txt file, and one apparently from FS's database. So there could be an issue w/ either entry for a given runway, but I did not experiment w/ the runway entries that begin w "FS;". But they both should be checked (also have to wonder if even a small discrepancy in altitude between the two runway entries causes problems).

 

Mike

Everyone's ARPT_RWY.dat is different. I haven't seen any FS entries in mine for example.

[Alex155 0]

Hi guys!

 

And what the solution of this problem?

 

1504 AIRCAC, the same problem...

[Mike777 163]

 

 

And what the solution of this problem?

 

Hi, Alex155,

 

Have you tried deleting ARPT_RWY.dat in fsx>PMDG>NavData  ?  You can back it up first to be on the safe side.  It will rebuild the next time you reload the 777.

 

PMDG wants everyone to use full names in its forums.

 

Mike

[Alex155 0]

 

Have you tried deleting ARPT_RWY.dat in fsx>PMDG>NavData  ?  You can back it up first to be on the safe side.  It will rebuild the next time you reload the 777.

 

Thank you for reply, but it doesnt help  :(  Still have "Terrain" warning on landing phase.

 

Now i am pushing "Terr ovrd" button (Near gear lever) on final, to disable this warning. But i hope to find other solution of this problem.

 

Alex

[777simmer 117]

Thank you for reply, but it doesnt help  :(  Still have "Terrain" warning on landing phase.

 

Now i am pushing "Terr ovrd" button (Near gear lever) on final, to disable this warning. But i hope to find other solution of this problem.

 

Alex

I guess that when you updated to 1504 you reintroduced the problem?

 

I think what Mike meant is that you have to go through the same procedure each time untill Navigraph puts in the proper elevation numbers in their Airac cycles.

Just saw this thread.  A few points and suggestions:

 

The file WpNavApt.txt has entries for each airport runway.  It is updated as part of each new Airac.  The last 5 digits of each runway entry are the altitude for that runway.  For example KATL is 01026. 

 

 

I did not know the 777 terrain database is updated from the Airac cycles.

Interesting and cool!

 

I wonder how terrain height is known when away from an airport though and how that terrain data can be updated to reflect FSGenesis mesh for example.