"terrain terrain" "pull up"

[Wennerholm 44]

   Hi! Do not take into account that LOWI may be too small for the B747. When I am at final at LOWI LOCR26, I get "terrain" and "pull up" warning. I have the right baro set with regard to AS for P3Dv4 and a valid route with STAR TULS3A. I catch GS but not the LOC. What am I missing?

[Budbud 227]

32 minutes ago, Wenholt said:

I get "terrain" and "pull up" warning. I have the right baro set with regard to AS for P3Dv4 and a valid route with STAR TULS3A. I catch GS but not the LOC.

Hi,

First the GPWS "terrain" warning is based on the radio altimeter (it basically physically detects that the height over the terrain is decreasing fast and is too low).

As far as I know the altimeter setting has nothing to do in the callout.

In real there may be some other things than the ground that can trigger a Terrain warning. There was a case of a 737 in Asia that got that warning at FL250 when crossing huge hailstones in a thunderstorm.

Anyway in the sim, it may be an issue with the scenery itself with wrong definition, or you are too low and not in landing config. I don't have the FCOM at reach to check the conditions for the callout but I believe that the landing gear at least must be down below a certain altitude in order not have the callout in approach.

As for the GS capture without the loc, it is quite surprising since there is no ILS at LOWI, there should be no GS at all... So you should be able to establish on the LOC but not the GS.

Is the LOC frequency in the FMC matching the one in the sim?

[Wennerholm 44]

LOWI is odd. There is a GS bot no ILS. I use ORBX Global range and ORBX arpt. I don´t know if the LOC frequency in the FMC matching the one in the sim. I only compere FMC with Navigraph charts. I extend the LDG at 5500 ft and full flaps at 4400 ft (arpt elevation 1907 ft). I only get GPWS at LOWI approach.

[scandinavian13 5,192]

On ‎12‎/‎9‎/‎2017 at 0:18 PM, Wenholt said:

There is a GS bot no ILS.

There are design tolerances for it to be called an ILS. Outside of that, it gets called an LDA, or similar.

On ‎12‎/‎9‎/‎2017 at 0:18 PM, Wenholt said:

I only get GPWS at LOWI approach.

Of course you do...it's buried in the mountains. This is no more odd than not getting a GPWS warning in Miami (completely flat).

[Wennerholm 44]

Thank´s for the information about the design tolerances.