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Vnav issues


jiasm

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Hello, Is it normal to keep adjusting the v/s knob nearly the whole approach to avoid loosing the descent path, it seems the aircraft doesnt fallow correcty the descent path, eventhough I start my descent early, because of this problem I cannot make a proper ILS approach and I arrive to high to intercept the glidescope, I dont know if I am doing something wrong.

 

thanks

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So far I also have not been able to make a managed descent without using full speedbrakes for the most part of the descent...But I think it was mentioned that it is a issue they are working on...

 

best regards

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Are you sure you entered the correct wind forecast for the descend?

If no wind is entered the aircraft assumes a calm wind condition so having a tailwind will force you into a high energy situation.

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hmm....I requested wind data uplink before takeoff.  Doesnt that include descent forecast data ? All flights very short hops so far, so I think there was no big wind change  between takeoff and descent. But I will have a closer look on that next flight...Maybe I missed something anywhere...

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Just tried another flight, wind forecast was correctly entered and even with some headwind.........but unfortunately no chance to stay on the descent path without speedbrakes . It just drops so quickly  after the descent point (and I even started descent a little bit earlier) I always get more or less the following situation without speedbrakes (descent was from FL 380 without speedbrakes , and until this moment no recovery of the vertical path despite mostly extreme descent rate...):

 

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best regards

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5 hours ago, Emanuel Hagen said:

Are you sure you entered the correct wind forecast for the descend?

If no wind is entered the aircraft assumes a calm wind condition so having a tailwind will force you into a high energy situation.

 

How is the wind data forecast entered?

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  • Deputy Sheriffs
38 minutes ago, jiasm said:

 

How is the wind data forecast entered?

Request Wind data on INIT A page. Then press Update Wind on every Wind page (climb/cruise/descent)

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Yeah I have noticed that the VNAV on descent needs tweaking. It's a bit jarring when you hit the knob to descend and ones the profile comes in it dives down at nearly -5000fpm and pulls up back to -2000fpm. I don't think passengers would appreciate that so much.

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For example, flying this route from EKCH to LOWW: SIME1E SIMEG Z493 XELOL Z491 VAVUN L996 DENKO L616 DESEN/N0460F370 DCT MORKO DCT MIKOV MIKO7W

Initiated descent 5 miles before TOD. Airplane descended at -1000fpm as normal, but then went crazy as soon as it intercepted the profile.

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I just set a new record... lol

2018-7-15_20-30-9-711.bmp

I have no idea whats going one but it makes this plane for me unflyable.

If I ajust the v-speed by hand the level-offpoint starts moving around the path. I guess it has something to do with the winds, but I can't add any on the INIT page...

I hope you will fix this in the next update(s) or can anybody tell me what I'm doing wrong?

 

 

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Any chance for a video of a situation like this? I am unable to recreate it on my rig and it seems to affect only a relatively small number of users for the moment.

Mabye you do something different than we do here which causes the issue.

 

Are you absolutely sure all required information is entered on all FMGS pages? Does the same issue happen for you during the tutorial flight?

What happens if you fly without weather?

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As mentioned before my problem might be that I cannot insert wind data, and that is why I have to use very frequently the V/S knob in the approach to follow the descent path.

I read that the only way to insert this data is to have company routes, and also insert routes to AS16. I usually insert my route waypoints manually.

 

Would there be an easier way to have wind data available?

 

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made three more short test flights:

 

first flight without any weather  (LIML-EDDM):   worked quite fine, no significant deviation from descent path, speedbrakes only punctually needed

 

second flight with weather (Aktive Sky) (EDDM-LIML):  worked quite fine (first time I see that) , except a very steep "diving" just after initiating the descent to catch the vertical path (down to 6000 fpm !) But then it recovered the path and more or less stayed on it 

 

third flight with weather (Aktive Sky) (LIML-LIRF): No chance to stay on the path without speedbrakes from the very beginning

I dont know how to do videos, so I at least made a series of shots to illustrate what happend:

 

SITUATION IN CRUISE SHORTLY BEFORE DESCENT with wind data entered and updated 

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SEQUENCE OF SITUATIONS RIGHT AFTER INITIATING DESCENT DOWN TO FL 240 without speedbrakes (actually started descent more or less 2 miles before TOD)

 

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AT FL240 USE OF SPEEDBRAKES TO RECOVER VERTCAL PATH   (recovered at FL 200 steeply descending)

 

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AFTER PATH RECOVERY SPEEDBRAKES RETRACTED AND LOSS OF PATH AGAIN...

 

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So far this happened for me as well with every flight when starting managed descent. When it started, the rate was fine but somewhere getting closer to the selected alt. it started to "chase" the purple dot.

 

route: EDDV/EDDM

 

Due to upload restrictions the images do not allow to see the following information. If required, I can provide a full resolution-version.:

Descent Start: 1000ft/m
seconds later: 5800ft/m

then: 4500ft/m ... 4300ft/m    etc.

 

For this flight I stopped it @3800ft/m because ATC requested to change the route and therefore managed descent mode was left.

 

If this is the mentioned problem which is already planned to be fixed with upcoming patches, its fine, of course I/we wait. Just want to make sure + share this is not a new one.

 

 

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Happens to me all the time. Decent is to late and it dives like crazy, Speedbrakes are out 90% of the time and i could use bigger ones. At the moment i take the prediction from Pro ATC which is way earlier, but as soon as the "real" Glidepath comes in i could use some additional airbrakes...Just an example EGSS DCT CLN DCT CLN M84 EVMEK UM84 KONAN UL607 KOK UM150 PITES DCT EDISA Y852 NATOR UN850 DEGAD Z424 AKASU DCT AKASU DCT SOKBU LIMC. FL390. PRO ATC predicts around a few miles around Nator to start the descent, the Airbus predicts between Degad and Basgo, which is to late. The old Airbus does this way better. 

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