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Loosing speed midflight


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This just happened to me last night.   In cruise at FL30, .73 mach. I took my attention away from the sim for ~ 30 seconds, when I looked up, speed had was decaying through 220 knots.   I went to CLB power, still losing speed.   Went to full thrust, no change.  Disconnected AP, nose down and it took forever to regain speed at max power.   I was too busy to take a screen shot but it was a clear night, no icing indications, I did have engine inlet heating on.   I have no idea what happened.   At first I thought maybe I bumped into the throttle by mistake or hit a key and turned something off.   That wasn't the case.  With everything going on, I didn't have a chance to check trim. 

 

Never seen anything close to that before. 

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3 hours ago, jay jay said:

This just happened to me last night.   In cruise at FL30, .73 mach. I took my attention away from the sim for ~ 30 seconds, when I looked up, speed had was decaying through 220 knots.   I went to CLB power, still losing speed.   Went to full thrust, no change.  Disconnected AP, nose down and it took forever to regain speed at max power.   I was too busy to take a screen shot but it was a clear night, no icing indications, I did have engine inlet heating on.   I have no idea what happened.   At first I thought maybe I bumped into the throttle by mistake or hit a key and turned something off.   That wasn't the case.  With everything going on, I didn't have a chance to check trim. 

 

Never seen anything close to that before. 

Are you using live weather? Did you check the OAT? Has happened to me that the live weather makes a radical change and the speed changes abruptly.

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20 hours ago, John2 said:

Are you using live weather? Did you check the OAT? Has happened to me that the live weather makes a radical change and the speed changes abruptly.

Now that is something I never thought of.  Yes, I was using LW but no, I never thought to check outside air temps.   Must have been a massive change to inhibit the jet from getting past 220 knots, even at max power.    I thought that was one of the issues addressed by Asobo in the last update?

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1 hour ago, jay jay said:

Now that is something I never thought of.  Yes, I was using LW but no, I never thought to check outside air temps.   Must have been a massive change to inhibit the jet from getting past 220 knots, even at max power.    I thought that was one of the issues addressed by Asobo in the last update?

Well yes I think that Asobo have supposedly fixed the live weather and I haven't had any problems with the CRJ climb performance for a while. I just wondered if live weather was acting up again.

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On 2/9/2022 at 11:33 AM, lasowitzse said:

This has happened to me two days in a row.  Both between FL320 and FL350.  1st Flight KDEN to CYWG.  2nd CYWG to KORD.  Anti Ice was on.  No warnings full throttle and still could not maintain speed or altitude.  Any idea what is causing this.

Cause, most likely pilot error and lack of immediate action to a developing issue.

 

1. Wing anti-ice draws air from the engine and in fact when it is on you will notice that your thrust will decrease.  It is not a good idea to have it on, climbing at these altitudes, if no visible moisture (clouds) is present.  If needed, level off and do not continue the climb. I have never had the anti-ice on in the flight levels.  Icing will general not occur above 3000 ft.  Make sure your sim is set to visual effect only under Icing in the settings.   I haven't tested it out lately, but the in-sim engine would just ice the plane up once the temp was below 0C.  This is not realistic. 

2. If you continue the climb, you will lose speed because at reduced thrust there is not enough thrust to climb AND maintain airspeed.  

3.  I am guessing you were climbing with VS mode engaged, otherwise the aircraft would have pitched up, down or neutral to maintain the selected airspeed.  Another reason SPD mode is used for climb.

4. Once you get behind the curve, the CRJ engines do not have enough thrust to firewall and fight their way through an issue.  You only have two alternatives.  Trade altitude for speed, stabilize and then continue the climb if able or fight the physics and make a big hole in the ground while scattering aluminum and virtual body parts all over the place. 

 

Climb at 290 Kias until the transition (290 Kias becomes Mach 0.74) then Mach 0.74 to altitude.  While doing this monitor.  Do not go pee.  Do not get a beer or soda.  Do not run to the store for a hot pocket.  The CRJ does not have the power or automation to be left alone and it inherently suffers from separation anxiety.  

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Cruizing … fl 370 …  mach 0.74 … without warning dropping airspeed ..  full throttle … keeps dropping … stalling 

 

Picking up speed …. Not able to climb anymore after enough speed gained .. same things happening. 
 

Quitting  msfs after 2 hour stable cruise.

 

jiha … 3rd time this happens randomly during cruise with hundreds of hours on CRJ 

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2 hours ago, DGH said:

Cruizing … fl 370 …  mach 0.74 … without warning dropping airspeed ..  full throttle … keeps dropping … stalling 

 

Picking up speed …. Not able to climb anymore after enough speed gained .. same things happening. 
 

Quitting  msfs after 2 hour stable cruise.

 

jiha … 3rd time this happens randomly during cruise with hundreds of hours on CRJ 

Real weather?

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On 2/11/2022 at 12:07 PM, jay jay said:

Now that is something I never thought of.  Yes, I was using LW but no, I never thought to check outside air temps.   Must have been a massive change to inhibit the jet from getting past 220 knots, even at max power.    I thought that was one of the issues addressed by Asobo in the last update?

They continually break it again - I've noticed patchdays seem to undo a lot of the work they do ( not always though ), and then the sanity altitude ( above which unpredictable wierd weather fronts can pop up ) gets progressively higher again. You do notice when there's some odd live weather shift though, it's often violent & might also kick you into overspeed.

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While I am sure you are trying to help every one of your assumptions is incorrect. I was at stable level flight  I was not using VS mode and I was watching it closely which is why I was able to recover it after a lot of altitude drop. It most certainly wasn’t pilot error. It was either sim bug or crj bug.  My guess is weird weather changes but the AP is trimming way up even when I am trying to decend and I don’t mean during the near stall events. I mean recovered my airspeed, level hand flying and I engage AP and straight pitch up. 

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On 2/12/2022 at 11:02 AM, Crabby said:

Cause, most likely pilot error and lack of immediate action to a developing issue.

 

1. Wing anti-ice draws air from the engine and in fact when it is on you will notice that your thrust will decrease.  It is not a good idea to have it on, climbing at these altitudes, if no visible moisture (clouds) is present.  If needed, level off and do not continue the climb. I have never had the anti-ice on in the flight levels.  Icing will general not occur above 3000 ft.  Make sure your sim is set to visual effect only under Icing in the settings.   I haven't tested it out lately, but the in-sim engine would just ice the plane up once the temp was below 0C.  This is not realistic. 

2. If you continue the climb, you will lose speed because at reduced thrust there is not enough thrust to climb AND maintain airspeed.  

3.  I am guessing you were climbing with VS mode engaged, otherwise the aircraft would have pitched up, down or neutral to maintain the selected airspeed.  Another reason SPD mode is used for climb.

4. Once you get behind the curve, the CRJ engines do not have enough thrust to firewall and fight their way through an issue.  You only have two alternatives.  Trade altitude for speed, stabilize and then continue the climb if able or fight the physics and make a big hole in the ground while scattering aluminum and virtual body parts all over the place. 

 

Climb at 290 Kias until the transition (290 Kias becomes Mach 0.74) then Mach 0.74 to altitude.  While doing this monitor.  Do not go pee.  Do not get a beer or soda.  Do not run to the store for a hot pocket.  The CRJ does not have the power or automation to be left alone and it inherently suffers from separation anxiety.  

While I am sure you are trying to help every one of your assumptions is incorrect. I was at stable level flight  I was not using VS mode and I was watching it closely which is why I was able to recover it after a lot of altitude drop. It most certainly wasn’t pilot error. It was either sim bug or crj bug.  My guess is weird weather changes but the AP is trimming way up even when I am trying to decend and I don’t mean during the near stall events. I mean recovered my airspeed, level hand flying and I engage AP and straight pitch up.  Also I climb exactly the way you describe unless there are restrictions on the SID. 

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6 hours ago, lasowitzse said:

While I am sure you are trying to help every one of your assumptions is incorrect. I was at stable level flight  I was not using VS mode and I was watching it closely which is why I was able to recover it after a lot of altitude drop. It most certainly wasn’t pilot error. It was either sim bug or crj bug.  My guess is weird weather changes but the AP is trimming way up even when I am trying to decend and I don’t mean during the near stall events. I mean recovered my airspeed, level hand flying and I engage AP and straight pitch up.  Also I climb exactly the way you describe unless there are restrictions on the SID. 

Where were you flying? Yesterday I flew the 900 from KSJC to CYVR at FL360 without any issues. I haven't had any issues flying in North America since SU7. On USA East server.

 

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7 hours ago, lasowitzse said:

While I am sure you are trying to help every one of your assumptions is incorrect. I was at stable level flight  I was not using VS mode and I was watching it closely which is why I was able to recover it after a lot of altitude drop. It most certainly wasn’t pilot error. It was either sim bug or crj bug.  My guess is weird weather changes but the AP is trimming way up even when I am trying to decend and I don’t mean during the near stall events. I mean recovered my airspeed, level hand flying and I engage AP and straight pitch up.  Also I climb exactly the way you describe unless there are restrictions on the SID. 


 

yes that is correct .. forgot to mention  … as soon as i have speed again … and switch on the AP … automatically max trim UP. Disconnect again fly level and mach 0.74 manually … AP on … max trim up etc etc etc 

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24 minutes ago, DGH said:


 

yes that is correct .. forgot to mention  … as soon as i have speed again … and switch on the AP … automatically max trim UP. Disconnect again fly level and mach 0.74 manually … AP on … max trim up etc etc etc 

Using live weather? Where are you flying? What server? Notice any abrupt changes in OAT?

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3 hours ago, John2 said:

Where were you flying? Yesterday I flew the 900 from KSJC to CYVR at FL360 without any issues. I haven't had any issues flying in North America since SU7. On USA East server.

 

North America, it’s happened to me on a couple of flights identifier/cywg, cywg/kord, Kiah/ kiad. I believe live weather is on. It’s not all the time but when it happens there are zero warnings ice/etc. throttle at max and the speed still won’t recover at level flight. Pretty sure I am on USA E ast servers. I didn’t notice any more weird OAT than usual on any other flights. 

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54 minutes ago, DGH said:

Europe … live weather … no OAT weirdness … no icing alert …. Nada

 

 

Maybe try North America to see if it happens there?

 

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45 minutes ago, lasowitzse said:

North America, it’s happened to me on a couple of flights identifier/cywg, cywg/kord, Kiah/ kiad. I believe live weather is on. It’s not all the time but when it happens there are zero warnings ice/etc. throttle at max and the speed still won’t recover at level flight. Pretty sure I am on USA E ast servers. I didn’t notice any more weird OAT than usual on any other flights. 

That's weird. It used to happen to me periodically but I am pretty sure it was when Asobo was having weather issues. Hasn't happened to me for a while now.

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1 hour ago, John2 said:

That's weird. It used to happen to me periodically but I am pretty sure it was when Asobo was having weather issues. Hasn't happened to me for a while now.

I flew yesterday KCVG/KEWR and no issue.  That's what is so frustrating because it just happens randomly.  2 days ago I was flying turned the AP on and it tried to an immediate barrel roll.  No CG or balance issues.  Happened for about 10 minutes and then it stopped.  Just not sure what is going on.  

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12 hours ago, lasowitzse said:

While I am sure you are trying to help every one of your assumptions is incorrect. I was at stable level flight  I was not using VS mode and I was watching it closely which is why I was able to recover it after a lot of altitude drop. It most certainly wasn’t pilot error. It was either sim bug or crj bug.  My guess is weird weather changes but the AP is trimming way up even when I am trying to decend and I don’t mean during the near stall events. I mean recovered my airspeed, level hand flying and I engage AP and straight pitch up.  Also I climb exactly the way you describe unless there are restrictions on the SID. 

The concept is the same.  It is a weather change.  Probably a combination of pressure changes and winds aloft.  The pressure change caused the aircraft to lose altitude on the tape.  The wind shifts probably took away some head wind component.  The CRJ tried to immediately climb back to altitude but had no speed to do it.  The autopilot disconnected.  You did not hit the autopilot bar before trying to connect and you got the behavior you saw.  I don't know if this is real life like behavior or not.  I have had this happen in the past, though not much lately with in sim real weather.  I also saw the behavior on AP reconnect.  The only way I have found to not have this happen is disconnect from the bar also.  Once stable, bar up, ap on. 

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On 2/15/2022 at 1:32 PM, Crabby said:

The concept is the same.  It is a weather change.  Probably a combination of pressure changes and winds aloft.  The pressure change caused the aircraft to lose altitude on the tape.  The wind shifts probably took away some head wind component.  The CRJ tried to immediately climb back to altitude but had no speed to do it.  The autopilot disconnected.  You did not hit the autopilot bar before trying to connect and you got the behavior you saw.  I don't know if this is real life like behavior or not.  I have had this happen in the past, though not much lately with in sim real weather.  I also saw the behavior on AP reconnect.  The only way I have found to not have this happen is disconnect from the bar also.  Once stable, bar up, ap on. 

Im not sure why you keep assuming what I am doing.  You are incorrect again.  I disengaged the AP with the bar, descended to regain speed.  Full throttle at level flight and I was still losing speed.  After a while dropping to almost 140knts I started gaining speed, bar up reset my altitude etc and engaged AP.  Straight nose up.  Please stop trying to put words in my mouth.  

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27 minutes ago, lasowitzse said:

Im not sure why you keep assuming what I am doing.  You are incorrect again.  I disengaged the AP with the bar, descended to regain speed.  Full throttle at level flight and I was still losing speed.  After a while dropping to almost 140knts I started gaining speed, bar up reset my altitude etc and engaged AP.  Straight nose up.  Please stop trying to put words in my mouth.  

OK.  Just continue what you are doing then.  I don't have this problem anyhow.  

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vor 12 Stunden schrieb lasowitzse:

Im not sure why you keep assuming what I am doing.  You are incorrect again. 

Dear @lasowitzse, if this issue is occuring that often on your end, please be so kind to make a video of it. You can basicaly record a lot then cut out the part that is "interesting".

 

 

Check out also this thread (also has videos in it):

 

As you have seen throught the topic, there are some SIM things that can not be controlled by AS, BUT, if you understand what happens, then you can easely work around it and still enjoy your flight.

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I have also encountered this on most of my longer flights, yesterday I was flying from KSEA to KLAX at FL310 cruising at about 280kts / 450GS or so with real weather on. I was not paying attention for probably less than a minute or so and indeed my speed had dropped down to 150 ish and had to use TOGA + VS of about -3 to get it back up to a good speed before I could stabilize again.

 

Quite strange and I only experience this issue on long flights with the CRJ, I don't see on i.e. the CJ4 (which also has just a FADEC right?).

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  • 3 weeks later...

I would like to contribute to this: OP has complained about the autopilot trim suddenly applying full scale trim after engaging the autopilot, despite establishing the aircraft in straight and level flight with proper trim. To this effect, I have identified the root cause of this issue, and have found it to be 100% reproducible.

 

The issue stems from the fact that the autopilot will remember its last "pitch trim setting" from its last disconnect, and upon reconnection will quickly set the trim to that value before allowing the aircraft to adjust. This gets extremely complicated by the fact that the user still has full authority over the elevator, so if the pilot disconnects the autopilot with the trim and control column "fighting each other", and retrims the aircraft so the control column and trim aren't fighting anymore, the aircraft will want to revert to the previous trim setting upon subsequent re-engagement of the autopilot (thus causing the nose to aggressively pitch up). So here are the steps to reproduce it:

  1. Make sure your aircraft is established in straight and level flight and trimmed properly to eliminate all control forces before engaging the autopilot for the first time
  2. Engage the autopilot in your desired modes (I chose HDG and ALT)
  3. Gradually apply nose down command on the joystick. You'll see the aircraft will slowly lose altitude and the trim will compensate by applying nose up trim.
    1. If you'd like to exacerbate the problem, accelerate the aircraft during this stage from a lower speed to a higher speed (e.g., 200 knots to 310 knots)
  4. Now disconnect the autopilot without moving your joystick, then reestablish your aircraft in straight and level flight.
  5. Once stabilized, re-engage the autopilot without changing the FMA commands (e.g., same heading and altitude hold as prior).

If you do this right, you will see the trim jump spectacularly to its previous value. Every time I've done this, I always ended up with the same result. @marcus_77I hope this is what you were seeing, because it's very repeatable.

 

(activate closed captions for step-by-step explanations)

 

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