Ils 21R question and landing clearances question

[FSXflyer12]

Oh thanks. come to think of it, I never applied any patches so mine might still have some bugs.
I'll try it again after installing the service packs.
typing this sat waiting to take off in a BAW 777, how geeky. phone off time.....

Well, happy flight. Also you may of not set something up right. Ryan said to submit a ticket and that they are big fans of airport design there.

[el_padrino]

This is what I wrote on PMDG's forum, but had not had any replies yet...

Been testing for some time all four approaches and the two 21s seem to have an issue. I am not really sure it's the NGX or the scenery, as both 03 approaches seem to be ok and the plane follows the glideslope as expected.

However in both 21 approaches there's a point right above some low hills that are circa 3 miles from the threshold where there's a sudden increase of thrust and then the AP seems to go higher than the glideslope, then dives steeply (c. 1300 fpm) to capture it again till it disconnects...

Is there any chance that there's some kind of updraft effect when the plane passes over these hills, that destabilises the approach? What troubles me is that this appears even when flying manually, like a step down the glideslope.. It's quite weird!

[george[flytampa]]

I'll investigate it further when I get back from vacation. I recall wacky ils performance even with the default 737 so I doubt it's a pmdg issue. I'll like to see if it works better with the default scenery first as i'm not sure how or if the scenery can effect it.

[Nils]

I once tried approaching ILS RWY 21R in Qualitywings 757. Right above the hills AP suddenly starts a steep descend.

[el_padrino]

George,

Did you have a chance to have a look at the 21 approaches? It happens every time (at least for me)...

Cheers,
George

[george[flytampa]]

Yes, I've been looking at it. Unfortunately I've not found any solution but I did discover 21L has the same problem with even the default scenery.

I tried the latest PMDG service packs & it still had same issue. Default Boeing 737 I recall not working well either so I doubt its a PMDG problem.

I'm not a hardcore airline guy so I have some dumb system questions. Is 21L even a CAT III Approach? I understand that a CAT III is needed for a full autoland? So if 21L is only a CAT II, something crazy like our erratic autopilot behaviour might be normal? My LGAV charts are years out of date but all the approaches seem to be only CAT II.

PS. I should add that just one single 21L autoland worked correctly. 1 approach out of ~20 I'm afraid. No idea why the other 19 failed.

[el_padrino]

Well as far as I know it doesn't really matter if it's CAT II or III. In FSX the plane will autoland if there's ILS.

[george[flytampa]]

I still have no idea why this is happening.

I uploaded a video of both Default & Flytampa Athens sceneries. The disconnect effects both versions even though the aircraft drifts out of control in varying directions.

Anyone else with this problem have any Greek Scenery installed? Mesh, Coastlines etc.

Video here....
http://youtu.be/LsFH65K01QI?hd=1

[athenian]

Yes, I've been looking at it. Unfortunately I've not found any solution but I did discover 21L has the same problem with even the default scenery.

I tried the latest PMDG service packs & it still had same issue. Default Boeing 737 I recall not working well either so I doubt its a PMDG problem.

I'm not a hardcore airline guy so I have some dumb system questions. Is 21L even a CAT III Approach? I understand that a CAT III is needed for a full autoland? So if 21L is only a CAT II, something crazy like our erratic autopilot behaviour might be normal? My LGAV charts are years out of date but all the approaches seem to be only CAT II.

PS. I should add that just one single 21L autoland worked correctly. 1 approach out of ~20 I'm afraid. No idea why the other 19 failed.

I believe that FSX completely disregards the ILS categories. A runway either has an ILS, or does not. There is no intermediate status.

So the only things you have to do in some aircraft to have them take you completely down to the runway are:
- set Baro/Radio to Radio (on both Captain and FO)
- set Radio to 0 (on both Captain and FO)
- on Boeings, after you hit the APPR button (after the LOC button), you must enable all (2 or 3) autopilots (on the 747-400X this happens automatically, on the 737NGX it does not)

The above three apply for the PMDG 747-400X, 737NGX and MD-11X.

George, does this happen with both 21s runways, or only with L or R?



PS: Since I have the scenery, I'll try and do an 21R ILS approach in the following days and see what happens (I also have FS Global 2010 X).

[george[flytampa]]

It happens on both L & R ( I heard). Not tried autoland on 21R myself yet.

[athenian]

OK, I did some further investigation on this, with FlyTampa Athens.

Did a short flight with PMDG MD-11 from LCLK to LGAV (there was south wind yesterday in the Athens area, abd it was a good opportunity to test this).

After I saved at the top-of-descent, my first approach was and ILS-Z (via KRO transition, SID was VARIX) approach onto 21R.

Then, after touchdown, I reloaded the saved flight, and did the exact same approach ILS-Z onto 21L.

Findings and conclusions:

- There are hills to the north of both runways, directly (or almost directly) below the glideslope, at about 800ft altitude.

- 21L does not pose a problem however, as the highest point of the hill is somewhat to the left or right of the glideslope, and not directly below it

- The problem lies in 21R only, when at about 800ft altitude, the MD-11 issued a ground proximity alert (the female voice), when radio altimeter dropped from the normal 400ft (800-400=400 as LGAV has an elevation of around 400ft) below 200ft and at some point it even almost touched 150ft. All this time, on my PFD, apart from the radio altimeter indication (which as I said, almost went down to 150), I could also see a large portion of the altitude tape on the right, being filled with yellow (it is the ground in the MD-11).
HOWEVER, the autopilot of the MD-11 NEVER disengaged, nor its APPRLAND (the equivalent of LOC+APPR on Boeings) lost or stopped following the glideslope. The aircraft remained at all times in a "DUAL-LAND" fully automatic landing. I had a perfect touchdown with a perfect flare, WITHOUT any intervention on my part.

I remember having the behavior that George mentioned, with the 737NGX, only with 21R, I don't remember whether I had it or not, with 21L.

So, some more conclusions:

- The ground proximity problem is much greater on 21R than on 21L.
- There might some code in the PMDG 737NGX that offers some sort of automatic "minimal ground avoidance and separation".



PS: I will try to do the same approaches in the following days with the PMDG 747-400X, and the PMDG 737NGX, and see what happens.

I have no other planes apart from these 3, so that's the best I can do.



UPDATE:

Now did the two approaches with the PMDG 747-400X.

Again the same flawless behavior. The only minor difference, that (apparently due to different design) the plane did not issue a ground proximity warning when approaching 21R, radio altimeter dropped below 300 (and down to 150). But again, the autopilot and the LOC-APPR did NOT disengage, and the plane landed flawlessly with flare and touchdown.



UPDATE-2:

Now did the two approaches with the PMDG 737-NGX.

Again the same flawless behavior. Identical to the MD-11 (with the ground proximity warning at 800ft while approaching 21R). But again, no autopilot or LOC-APPR disengage, perfect landing and touchdown with flare.



FINAL CONCLUSION:

Given what I tested, and what I've read in this thread, I can only conclude that there is something wrong at these points with the default elevation-mesh of FSX.

All the above tests that were done with FS Global X 2010 installed, lead to proper touchdowns.

[oa820]

From what I know the mountains have been cut off to help airplanes with their approach. When the airport started construction we had a small issue in Athens. Most of the Radio stations had to relocate their antennas cz they would cut that mountain for approaching planes.
And I haven't noticed anything like that in the fs9 version.. I have noticed though that the default ATC will clear you at 1900ft before getting the glideslope at Rwy21L and at 3000ft for the Rwy21R and the same will happen for the opposite ones.... 1900ft for 03L and 3000ft for 03R...