PMDG 777 false terrain alarm

[FlyingAxx 2]

it kept warning terrain terrain pull up

NOT too low terrain

and NEVER too low gear

OR too low flaps

yes I did programme the FMC correctly, including the VREF

 

 

I've had the same problem with the NGX quite a while ago. It had been fixed after re-installing it again. An other reason could be that the Navdata are corrupt for whatever reason. In such a case it might happen also with other PMDG birds (it's just guessing).

[cathay747 0]

yeah I did recall that the ngx Once suffered from a similar problem

but how could the navdata be affected?

 

perhaps its time to switch to the MD11 for the time being

[downscc 1,327]

 

 

but how could the navdata be affected?

 

Navdata could be the source for the airport elevation and location... PMDG does not typically peek into bgl files but depends on navdata for lots of stuff.

[Capt Speirs 52]

 

 

perhaps its time to switch to the MD11 for the time being

 

Great bird, but a steep learning curve for me. MD-11 seems to be a cross between Airbus and Boeing, way ahead of its time.

[cathay747 0]

by the way I already reinstalled the 777, so I'm really running out of solutions

[kevinh 409]

Navdata could be the source for the airport elevation and location... PMDG does not typically peek into bgl files but depends on navdata for lots of stuff.

EGPWS terrain warnings come from radio altitude and its internal terrain database. Neither of which are affected by Navdata.

 

PMDG may be using the selected airfield elevation to "fine tune" terrain elevation calculations. Other than that I don't see why selecting the origin and destination airport in the FMC should have anything to do with preventing terrain warnings.

[scandinavian13 5,192]

 

 

Other than that I don't see why selecting the origin and destination airport in the FMC should have anything to do with preventing terrain warnings.

 

So if I descended into a random field in landing config I shouldn't get a warning?

(That's a legitimate question - I was assuming the selection of a dest field suppressed the TOO LOW annunciations. Nothing to do with the nav data directly, elevation-wise. Just the airport location.)

[downscc 1,327]

 

 

EGPWS terrain warnings come from radio altitude and its internal terrain database. Neither of which are affected by Navdata.

 

I think you're correct.  My original thinking was runway information (location, extended centerline etc) was involved but a quick search revealed that only inhibit is from landing configuration (gear down and flaps set for landing).  A data error, if exists, would be in the .DEM files and everyone could reproduce the same false positive.

 

You should be able to land in a corn field without GPWS warning as long as you have gear and flaps down and out.

[scandinavian13 5,192]

 

 

You should be able to land in a corn field without GPWS warning as long as you have gear and flaps down and out.

 

Ah, gotcha. Cool. That's what I get for not R'ing the FM.  :ph34r:

 

 

 

Other than that I don't see why selecting the origin and destination airport in the FMC should have anything to do with preventing terrain warnings.

 

Disregard the earlier post.

 

Thanks guys!

[doog79 43]

The other day I was landing 30R at OMDB in the 300ER.  Terrain calls all the way down the glideslope.  

 

Guess who forgot to set there altimeter at transition altitude. 

 

Just saying :ph34r:

 

Doogie Reid

[FlyingAxx 2]

yeah I did recall that the ngx Once suffered from a similar problem

but how could the navdata be affected?

 

perhaps its time to switch to the MD11 for the time being

That's a longer story. I've build my own database by using purely the existent airport and runway data of FSX. Unfortunately I didn't sort it by LAT/LON but by ICAO. This caused obviously the same problem as the NGX wasn't able to sort out all environment variables (according to PMDG's helpdesk). I think it had to do with run-time problems which is no contradiction. However, I shouldn't have mentioned it as this was definitely a very special case.

EDIT: I forgot to mention, that the data format wasn't the reason!

[cathay747 0]

The other day I was landing 30R at OMDB in the 300ER.  Terrain calls all the way down the glideslope.  

 

Guess who forgot to set there altimeter at transition altitude. 

 

Just saying :ph34r:

 

I am interested by this reply.

may I ask how do u set the altimeter at transition altitude?

 

Doogie Reid

[scandinavian13 5,192]

For clarification:

 

When descending, you change your altimeter from STD to local at Transition Level. Transition Altitude when ascending through the altitudes (local pressure). Transition Level when descending through the levels (STD pressure).

 

 

I am interested by this reply.
may I ask how do u set the altimeter at transition altitude?

You just set your pressure setting (by rotating the knob on the display control panel - it's the one with STD in the center) to the local altimeter setting, and then press STD. I believe this is discussed in the tutorial.

[doog79 43]

 

The other day I was landing 30R at OMDB in the 300ER.  Terrain calls all the way down the glideslope.  

 

Guess who forgot to set there altimeter at transition altitude. 

 

Just saying :ph34r:

 

I am interested by this reply.

may I ask how do u set the altimeter at transition altitude?

 

Doogie Reid

 

See Kyle`s answer above.  

I was dealing with 2 noisy kids at the time so forgot to set the altimeter to local pressure which resulted in me being much lower than I should have been.  Easy mistake to make if you get distracted on approach.  Just glad its a sim lol

 

Doogie

[scandinavian13 5,192]

 

 

I was dealing with 2 noisy kids at the time

 

Sterile flight deck rules are serious business!