Wrong ground elevation at FMMI on final Rwy 11

[isaaclevi]

Hi Hardy,

I got my psx yesterday and I am simply happy with it .Thank you very much for this awesome work,more than I expected.
I noticed for the ILS RWY11 at Ivato FMMI,my home base ,that we touch the ground at about 4800ft QNH on final ( 3.1 ils dme and for NDB Rwy 11 approach the minima is MDA(H) 4710'(513') cat D airplane ).We also had the same issue in FSX but the FSglobal brought the correct ground altitude.
In x-plane10,it is always correct like in real life, 1000ft AG is after passing the outermarker IO but not before as I see .
With PSX I fly the  LOC with VS till this touchdown and then I reengage the APP boutton for the CatII ,amazing this aircraft can do it.
I know that it is nothing compared to what you have done but I really appreciate if you could do something in order to increase the feeling. Good.

Best Regards.

isaaclevi
FMMI

[mikeindevon]

Are you using a scenery generator?  If so can you tell us which one: XView or VisualPSX?

Mike

[isaaclevi]

No ,I am not using any Mike,just the original PSX.

[mikeindevon]

If you were to use XView this would overwrite the ground elevation in PSX with the X-Plane values.

I expect VisualPSX does the same, but you would have to ask Garry that.

[Hardy Heinlin]

Hi Isaac,

in AIRAC cycle 1403 (which is currently used in PSX), the stored elevations are:

4196 ft for Rwy 11
4117 ft for Rwy 29

If this won't be corrected in cycle 1503, I will correct it manually and inform my nav data supplier who in return will inform the government in your country. Nav data suppliers have to use government data, even if the data is wrong. This also explains why other nav data suppliers may indicate the same errors.

What are the correct elevations there? Has anybody got scientific data?


Cheers,

|-|ardy

[Pierre Theillere]

Hi Hardy!

From Jeppesen chart 10-9, dated 5 APR 13:
Apt elev: 4198 ft
Threshold rwy 11: 4197 ft
Threshold rwy 29: 4117 ft
Unless there has been since april 2013, a huge landslide or tsunami there, it seems all's OK in PSx!

[Hardy Heinlin]

Hi Pierre,

I think Isaac is saying that the correct elevation is ca. 4800 ft and that the nav data published by the Madagascar government is wrong. Jepp, PSX etc. use government data.

Such errors happen.


Cheers,

|-|ardy

I misunderstood it. Sorry. You mean there is an OBSTACLE.

[isaaclevi]

Hi Hardy

These elevations are very correct and reflect the reality at FMMI, the problem is the little mountain (obstacle) in the runway axis easely seen respectively on the map (situation/position) and profile (analysis/Profile) during or after flying an ILS approach Rwy 11.
Please fly this procedure and you will see what I mean.This mountain has to be flattened ( roughly 2 or 3 nm long/wide ) in order to keep all existing ,officially established and flown procedures (my opinion) but it's up to you Hardy.1503 is next year and seems to be an eternity (joke).

Regards

isaaclevi
FMMI

[Hardy Heinlin]

Hi Isaac,

I got it now, and also flew it in PSX.

Indeed, this is not an error in the AIRAC cycles; it's not a navdata problem.

The problem lies in the resolution of the terrain database.

To fix this problem one could lower the respective terrain point value in the global terrain file by a binary edit, possibly by a little patch program. Correcting and uploading the whole global terrain file would not be reasonable as the file size is in the giga byte range.

Another solution might be me extending the runway elevation zone in PSX. There is a certain radius around the runways; within this radius, the exact elevation data of the runways are applied (nav database) instead of the coarser data of the terrain database. But I'm not sure if this could cause problems at other airports.


Sorry for that!

|-|ardy

[isaaclevi]

Hi Hardy,
I am glad you got it,let's wait for the patch,
thanks to all of you .

isaaclevi
FMMI

[Alec246]

Hardy,

Could you tell us what's the resolution of the Terrain Database used in PSX?

Thanks

[Hardy Heinlin]

Check the tiles on the map.

[isaaclevi]

If you were to use XView this would overwrite the ground elevation in PSX with the X-Plane values.

I expect VisualPSX does the same, but you would have to ask Garry that.

Hi Mike
Thanks for the advice, XView for x-plane10 solves the problem for good

isaaclevi
FMMI