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Kwacker

Terrain warning on final approach and landing

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I'm repeatedly getting terrain and pull up warnings flying into KPHX when on track and glide slope - including autolandings. Is there a way to inhibit these warnings on final approach? - better I would have thought the NGX would auto inhibit these on final. Could someone please advise - I don't see this mentioned in the manuals or forum.

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I don't think there is. If you're getting "Too low, gear, flaps", then yes. But if it'te telling you to pull up, then no. But how high are you? I live in Phoenix and I think you're way too low.


Kenny Lee
"Keep climbing"
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I don't think it is anything to do with KPHX - I'll run a test soon. I'm guessing something strange in the way I'm configuring the aircraft. Thing is, I don't recall seeing this before the service pack. I also did tens of flights into KPHX with no problem. Any one got any suggestions?

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The terrain can be inibit by the GPWS panel, and I think that the problem is related to someting like installed mesh in fsx.


Regards

Andrea Daviero

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ok - I found the GPWS inhibit switch - it's on the co-pilot side forward panel by the yoke. I wasn't seeing it as I don't fly copilot!Strange thing is I've never needed this before into KPHX..... is it standard procedure to inhibit this on final?I also noted there is an aircraft config option to set the GPWS to peaks mode - I'll play with this to see if something has changed.

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The too low terrain comes on in 2 ways, one is about the aircraft not configured for landing (flaps and gears) and the aircraft is below 1000Ft RA (mode 4), the other is mode 3 and it is for take off if the aircraft is not climbing.In the mode 4 that I think is the actual condition, you will have "too low terrain" message if you are below 1000ft of RA altitude and your gears are not down with airspeed >190kts, under 190kts you will hear "too low gear"If your speed is greater than (160Kts?) and you have flaps not set to landing, you will hear "too low terrain" or, below 160kts, "too low flaps"Normally Enhanced GPWS uses terrain database to ihnibit some aural messages at some locations where it is normal that a common GPWS alerts about something. This is needed to prevent alerts where the condition is still safe.


Regards

Andrea Daviero

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Ok, I ran a test. Landing 25L RNAV KPHX. About 700 feet radio altitude I get a terrain warning - see attached images. I believe I have the aircraft fully configured, speed correct, full flaps, gear down, right on glide slope according to instruments. I have to inhibit the GPWS to avoid getting pull up warnings.Any ideas? Maybe this approach is not in the terrain database?

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If I remember correctly (Tabs will correct me) the NGX terrain display uses FSX scenery mesh to show actual simulator altitudes.In your screen you can see the yellow area in front of you and if I can look correctly in your scenery there is no difference from green areas to the yellow ones.Maybe a scenery related issue?


Regards

Andrea Daviero

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We actually don't read the mesh Andrea - we had it working, but that method proved to be too prohibitive on performance during testing. The EGPWS reads the files in the FSXPMDGDEM folder - this is our own worldwide terrain data we compiled and it's accurate to the variable resolution that the real unit has. (shows higher resolution data around major airports vs. out in the middle of nowhere etc)Regarding those KPHX screenshots - a very prominent geographic landmark is missing in your shots - the large hill at Arizona State University that the school's football stadium is built into the side of. You fly right over it on approach to 25L in real life. That's obviously some kind of photoscenery you're using there and it doesn't look like it has an accurate mesh to me:Sun_Devil_Stadium.jpgKPHX is just beyond the peak of the hill in this photo.Also for what it's worth, I've never heard of anyone doing RNAV approaches into KPHX - they're published, but there's an ILS to that runway and that's what would actually be used.


Ryan Maziarz
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For fastest support, please submit a ticket at http://support.precisionmanuals.com

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Hi Ryan, Andrea and all, thanks for the replies.I flew the MS ultralight from the start of 25L to the hill by the football stadium. The hill is most certainly there. I must have been above it in the earlier screenshot. I also checked that there is no terrain (invisible or visible) to hit, the ground is very flat - I had no problem flying the ultralight at 100 feet.It looks to me like there must be a small error in the terrain database the EGPWS uses. I'll fly approaches into the other runways from that direction tomorrow to test those.Regarding RNAV into 25L, the reason I was using that is that if I look at the real world routes used on flightaware >95% are via GEELA5. That's published as an RNAV route. A few fly ARLIN3 from KSAN. I assumed as the plate for GEELA5 says RNAV this is what you should use - is it permissible to use ILS from GEELA5? 25L is certainly equipped for it. I've no real idea what is really done in the real world.... :(

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Same thing occurs on full autoland ILS into 26, same yellow blob on EGPWS changing to red and pull up warnings:

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Hi !Just tried that approach a few times with slightly different EGPWS setings, to see if that made any difference.It didn't !Pic 1. VC...... is with the Range Arcs and Terrain Peaks/Water in Cyan settings. (which I never use myself)Pic 2. 2D.......is without those settings. (just before selecting flaps 30 and my landing REF)Fail OP approach into RW 26 KPHX.( have you tried a clean install ? )Fred.


Frederic Steiner.

B7382.jpg

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Ryan, did you updated the terrain database over the various patches of the NGX? Maybe te issue is related to an old one?The yellow part seems to end on the runway.A bit strange that the hill finish on the runway.However, it is certainly someting related to Kwacker (What is your full name?, forum rules) installation.If the database is always the same maybe a corrupted installation I think.


Regards

Andrea Daviero

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