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A/C goes nose up when activating autopilot


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It's January 2022 and I'm still suffering from this bug, absolutely killing my enjoyment of the CRJ 700/900 in MSFS. At this point, I think Aerosoft just doesn't care, so I don't think I'll be able to ever care for another Aerosoft product. Worst part about it is, I really don't think this bug was present when the aircraft was first introduced, it had to come with one of the updates of the aircraft. This is just messed up.

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Had the same today above the alps … cruising normally… suddenly max trim

up and loosing speed. Disengage AP … pickup speed in slow decent .. AP on … max trim up …. Grrrrrrrrr

 

Restarted flight and no issue anymore ( only “reno air race” wobble since MARCH 2021 !! ) 

 

frustrating and no responses  from Aerosoft at all !

 

sorry but i do not care about the twotter … i BOUGHT the CRJ ! And this mess happened way before twotter release ! 

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I submitted a ticket with all details and a video to reproduce the issue more than two months ago. It took them two months to reply, that this is known and indeed considered a bug and the issue is not easily fixed. Then the ticket was closed.

Based on that brief exchange and the lack of responses in this topic, I doubt that Aerosoft is going to fix this issue or that they even care.

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I'm having a similar problem that randomly occurs (but seems to be getting worse).   During the last stages of my approach, when I activate VS for another descent, the aircraft instead will pitch nose up and start climbing.   No amount of spinning the "down wheel" makes any difference.   Since I'm already low and slow, I'm shortly on the verge of stalling and have to apply max thrust.  Usually at some point after I've gained 2-3 thousand feet, the aircraft starts to again descent.    This happened last night and to boot - despite being at 3,000' less than a mile from the runway threshold, it still showed that GS was captured!    

 

Granted, when this happens, I can disconnect the AP and manually bring the nose down but that kind of defeats the purpose of flying this sim "by the book" does it not?

 

Any idea what is causing this issue?  

 

 

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12 minutes ago, jay jay said:

I'm having a similar problem that randomly occurs (but seems to be getting worse).   During the last stages of my approach, when I activate VS for another descent, the aircraft instead will pitch nose up and start climbing.   No amount of spinning the "down wheel" makes any difference.   Since I'm already low and slow, I'm shortly on the verge of stalling and have to apply max thrust.  Usually at some point after I've gained 2-3 thousand feet, the aircraft starts to again descent.    This happened last night and to boot - despite being at 3,000' less than a mile from the runway threshold, it still showed that GS was captured!    

 

Granted, when this happens, I can disconnect the AP and manually bring the nose down but that kind of defeats the purpose of flying this sim "by the book" does it not?

 

Any idea what is causing this issue?  

 

 

Whether it is what should happen or not, check where the elevator trim has wound itself to. Usually this sort of thing happened when I got too slow at some point, just when pulling the nose up is least helpful...

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vor 2 Stunden , jay jay sagte:

 During the last stages of my approach, when I activate VS for another descent,

We saw this issue and I saw the videos. I also had it happen once. I never had it / saw it on descent. I realy don't understand how you are flying. As I see it (on descent) I always have AP on and descent from CRZ LVL using VS (starting 10nm before TD I mostly go VS -1000 then after passing TD I open the DIR INTC page and look at the descent and adapt VS to the "blue circle" and follow closely also the FMC descent). I always do the first decent to about 10000 (to be able to reduce speed) then make other descent acc. to ALT restrictions. During this time I never ever have to disco the AP. It is always on and following my imputs.

 

I had that nose up behaviour on CLB when I decided to handfly the ACFT to certain ALT (6000...max 10000) and kicked in the AP in a level flight (so I leveled the ACFT to my ALT and when I kicked in the AP, it went berzerk). Since then, I always fly VNAV on CLB and push AP during CLB at about 4000ft. I do not get the nose up behaviour that way.

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I've never had it on climbout - whether using SPD or VS - but I've had something similar happen pretty much every time I air-start & try and use ALT hold ( I say "pretty much" because I can't remember every time ). If I'm at a decent speed on approach ( usually Vref+some and a bit more at a mile out ) I've never had any issues holding a path vertically, but it definitely loves pitching up if you  fall down the back of the l/d curve ( as does the default Asobo GA AP I forget the model name of too ). I've started watching the elevator trim because I'm a little suspicious of it.

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4 hours ago, GEK_the_Reaper said:

We saw this issue and I saw the videos. I also had it happen once. I never had it / saw it on descent. I realy don't understand how you are flying. As I see it (on descent) I always have AP on and descent from CRZ LVL using VS (starting 10nm before TD I mostly go VS -1000 then after passing TD I open the DIR INTC page and look at the descent and adapt VS to the "blue circle" and follow closely also the FMC descent). I always do the first decent to about 10000 (to be able to reduce speed) then make other descent acc. to ALT restrictions. During this time I never ever have to disco the AP. It is always on and following my imputs.

 

I had that nose up behaviour on CLB when I decided to handfly the ACFT to certain ALT (6000...max 10000) and kicked in the AP in a level flight (so I leveled the ACFT to my ALT and when I kicked in the AP, it went berzerk). Since then, I always fly VNAV on CLB and push AP during CLB at about 4000ft. I do not get the nose up behaviour that way.

That's pretty much how I fly the jet.   The descent (until on final) is all A/P.   VS used exclusively for descending.   This only occurs when I am "low and slow", ie - descending to the level required to pick up the GS.  

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@jay jay this issue (as title states) happens when enabling AP (and I only saw it when enabling the AP from a level handflied ACFT). So if you fly AP till short final, it might be something else you are experiencing. Also if you say "low and slow" I suspect you are too slow and AP tries to stay on GS and looses significant speed in a short time so that it pitches up like crazy.

 

Would be nice to see a VID of your procedure.

 

***EDITED: Look at all the videos in this thread and you will notice all of them have the pitch up from manual flight then activating AP.***

Now I can also see some things I don't like in the videos:

First Video from Puukka: he activates AP with no mode selected (no NAV or SPEED)

Same goes for Czar66

SinusJayCee: flies the CRJ up to 14000 by hand and at the exact point he activates AP he gets an ICE warning (did he had icing effects on?????)

etc...

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8 hours ago, GEK_the_Reaper said:

Now I can also see some things I don't like in the videos:

First Video from Puukka: he activates AP with no mode selected (no NAV or SPEED)

Same goes for Czar66

SinusJayCee: flies the CRJ up to 14000 by hand and at the exact point he activates AP he gets an ICE warning (did he had icing effects on?????)

etc...

 

All of those videos show the exact same thing and the things you are picking out have no effect on trim. You don't need any modes selected to enable the autopilot. You don't even need the flight director enabled. By default it should engage in roll and pitch mode. And even in the video of the stream where ICE also comes on, you see the exact issue of the trim jumping towards neutral 7,5 when AP is engaged. 

 

Just saying, whether you like those things or not, they do not affect the actual problem described.

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Dear @CRJay I do see the change in trim on my end also. What I don't have is that violent pitching and loosing speed that makes me take command of the ACFT or plummet into the ground!

 

As I mentioned before, I'm not argueing that it does not happen (because I had it also ONCE and we see the videos), I'm argueing cause 99,9% it does not happen on my end. So if there is someone who can replicate this 100% (PITCHING and loosing speed) I would be glad to try to reproduce it.

 

I will show you how I fly and how it looks on my end -Stand by, I will upload a VID-

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Have to report I've just experienced this too - -1000, RNAV approach, VS -0.8, no coupled VNAV ( in the pad, if it's always enabled on the -1000 then I didn't have the VNAV button pushed anyway ), 160kts stable descent and out of nowhere the VS setting just went positive & kept going more and more positive, and disengaging it & re-engaging it didn't change anything. As I was almost at the runway I had to disconnect the AP, which given I was on final in cloud with no vertical guidance at all with the pitch trim way away from where it should be was ... interesting ( and I suspect somewhat panic inducing for the passengers ). Broke cloud lined up & only manageably high, so all was well.

Might be something to do with RNAV approaches? I don't use them when I have the choice of something else so not much experience with anything that can go wrong.

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@Richard Dastardly @CRJay @jay jay and others.

This is what I have on my system (all 3 VIDs taken last night):

1. TO and CLB from LOWI: Live weather (with extreme winds), I activate NAV->SPEED-> AP at about 4500ft (you do see the trim change but it has zero effect on the ACFT in that short time). BTW: I also do a DIR INTC at the beginning ;)

https://youtu.be/CjJhfdGNcyg

 

2. This short flight is a FPLN from EDNY to EDDM and covers 2 VIDs

2.1. TO and CLB from EDNY: weather theme "few clouds" -> In this CLB I actually did a STEP CLB waiting for the CRJ to level off before activating next STEP CLB

https://youtu.be/QCCDh74D23U

 

2.2. This part covers the DES (from before TOD) till touch down. DES again in STEPs (and yeah...TOD is there because some say it's not beeing shown)

https://youtu.be/pwTTHjMVV78

 

So guys...this is how I fly every single flight and I don't have any issues with the ACFT.

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A few weeks ago, I sent a video to the support team, I assume he has sent it to the devs?

In your videos, you are flying way to slow for the trim change to have any notable effect. To reproduce it during climb, do the following:

Accelerate to 250 knots, climb to FL100, accelerate to 290 knots, trim the aircraft (Should be quite low, 2.5 in my vid). Now engage the AP, it will trim to 7.5 and stall the aircraft.

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vor 22 Stunden , GEK_the_Reaper sagte:

SinusJayCee: flies the CRJ up to 14000 by hand and at the exact point he activates AP he gets an ICE warning (did he had icing effects on?????)

Sorry, I don't get it. Why should having icing effects turned on cause a sudden change in trim of a perfectly trimmed plane when enabling the AP?

 

vor 29 Minuten, GEK_the_Reaper sagte:

So guys...this is how I fly every single flight and I don't have any issues with the ACFT.

vor 16 Minuten, falcon55 sagte:

In your videos, you are flying way to slow for the trim change to have any notable effect. To reproduce it during climb, do the following:

Accelerate to 250 knots, climb to FL100, accelerate to 290 knots, trim the aircraft (Should be quite low, 2.5 in my vid). Now engage the AP, it will trim to 7.5 and stall the aircraft.

The speed itself doesn't make the difference, but the trim does. In all videos, the pitch trim is in the green band somewhere around the middle. The issue discussed here causes the AP to set the trim to 7-something. So when the trim is already in that range, the issue of course doesn't appear.

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vor 20 Minuten, SinusJayCee sagte:

Sorry, I don't get it. Why should having icing effects turned on cause a sudden change in trim of a perfectly trimmed plane when enabling the AP?

 

I can't give you astraight answer for that. I just saw that in the exact moment you pressed AP (and I mean literally in the exact moment), you had an ICE warning triggered (so it could have been a combined issue with something and we know that icing effects are so overdone that everybody puts them in visual only).

 

vor 28 Minuten, SinusJayCee sagte:

The issue discussed here causes the AP to set the trim to 7-something. So when the trim is already in that range, the issue of course doesn't appear.

 

And exactly this is a part of the "workaround". All customers here have experienced the trim change that should not happen (this has already been forwarded to the DEVs - I will again try to move it up the list). So if you look at the videos I posted, you can clearly observe that flying the Jet in a 8...6 TRIM range is perfectly achievable and will not lead to those issues.

 

vor 57 Minuten, falcon55 sagte:

In your videos, you are flying way to slow for the trim change to have any notable effect. To reproduce it during climb, do the following:

Accelerate to 250 knots, climb to FL100, accelerate to 290 knots, trim the aircraft (Should be quite low, 2.5 in my vid). Now engage the AP, it will trim to 7.5 and stall the aircraft.

 

I'm not a RLP but there are some in the BETA. I how many circumstances do RLP Handfly the JET above 10000ft?

So no...I'm not flying too slow, I'm flying in a normal way.

 

So please...my advice to you...till the release notes don't specify that the TRIM change has been fixed, please do not fly > 10.000ft, on CLB SPD (e.g. 290) then kick in the AP ;) then wonder....OMG.

 

 

PS:

Also please do keep in mind and carefully read all the replies in this thread cause some reports DO NOT TALK ABOUT THE TRIM CHANGE WHEN KICKING IN THE AP, but already in AP mode and when changing VS (which is totaly different thing)

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vor 6 Minuten, GEK_the_Reaper sagte:

I can't give you astraight answer for that. I just saw that in the exact moment you pressed AP (and I mean literally in the exact moment), you had an ICE warning triggered (so it could have been a combined issue with something and we know that icing effects are so overdone that everybody puts them in visual only).

I get your point, but I can confirm that the issue also happens in nice weather without icing :) (Just for clarification: This wasn't my video but the one from CptCanada.)

 

vor 11 Minuten, GEK_the_Reaper sagte:

And exactly this is a part of the "workaround". All customers here have experienced the trim change that should not happen (this has already been forwarded to the DEVs - I will again try to move it up the list). So if you look at the videos I posted, you can clearly observe that flying the Jet in a 8...6 TRIM range is perfectly achievable and will not lead to those issues.

I guess I misunderstood your previous two posts. I thought your aim was to show that it rarely happens to you, and of course it doesn't happen to you when you activate the AP earlier. But as a workaround, I'm fine with that.

 

Another workaround is to apply gentle pressure to the yoke (or stick or whatever you are using) when activating the AP. This will not cause the AP to disconnect but counteract the sudden trim change. You can gradually release the pressure when the AP starts to trim the plane nose down.

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vor 24 Minuten, SinusJayCee sagte:

I guess I misunderstood your previous two posts.

No worries..happens to all of us (thats why I stated to all to carefuly read all the posts)

 

I still can't figure how the "trim issue" kicks in during DES for some customers (because I always fly AP till short final.....).  Hope to see some VIDs.

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vor 3 Minuten, GEK_the_Reaper sagte:

No worries..happens to all of us (thats why I stated to all to carefuly read all the posts)

Reading your previous posts again in the context of your last post actually made it clear to me :)

 

vor 4 Minuten, GEK_the_Reaper sagte:

I still can't figure how the "trim issue" kicks in during DES for some customers (because I always fly AP till short final.....).  Hope to see some VIDs.

I haven't seen this issue either, but I also usually disconnect the AP after capturing the GS and at about 1000ft AGL. I handfly some approaches (e.g. LOWI circle-to-land to RW08), but here I had no issues either.

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Thank you @GEK_the_Reaperfor looking into our woes, it is much appreciated!

14 hours ago, GEK_the_Reaper said:

 

As I mentioned before, I'm not argueing that it does not happen (because I had it also ONCE and we see the videos), I'm argueing cause 99,9% it does not happen on my end. So if there is someone who can replicate this 100% (PITCHING and loosing speed) I would be glad to try to reproduce it.

 

You were asking for a 100% reliable way to reproduce the issue. This is why I suggested you to handfly to 290 knots above FL100, because the issue is very noticeable there. The earlier and slower you engage the AP and the closer the trim is to 7, the less noticeable the bug is. 

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@falcon55 @SinusJayCee @Richard Dastardly @CRJay @jay jay so guys...not realy the news youve been waiting for but here I go.

I raised the issue again in the team and we started to test the behaviour on standard ACFT from ASOBO. It came out that ALL of them (even the CJ4 -non standard ACFT) do the same thing -the time you kick in the AP it will TRIM to the default value and the revert to the state it was.

 

It's hard to see it in the TBM but get in it, take clear skies as weather theme, handfly it to e.g. 5000ft at max speed, trim it so it flies level (it's a a trim down and the trim indicator will be above the green band), kick in AP and you will se the indicator moving down (to it's initial value) then again up.

 

Some ACFT TRIM realy quick, some rather slower and depending to the ACFT and current flight conditions yada yada yada you will see more or less the effect.

 

At this time I would say it's a sim issue...

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