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kmanning

Auto-Pilot is NOT Engaging

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I've been very angry about this but the auto-pilot has not been engaging when I press it. It has done this on the 747 version 3 for the P3D and the 737NGX. Last night, I was flying the 737NGX and after departing Charlotte International at about 2 to 3 thousand feet, I pressed the auto-pilot button and it will not engage. What's the damned problem? I was not able to engage it until after reaching 37,000 feet, and after about 5 to 10 minutes, it finally engaged. It has engaged in the past and I'm using the same technique as I've always have. Yes, I've set the trim control, but the FS2Crew always comes behind me and resets it, but as far as know, it still should work. It is NOT doing what it's supposed to do.

Ken.

Edited by kmanning

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51 minutes ago, kmanning said:

It is NOT doing what it's supposed to do.

It actually probably is. The real autopilot will actually disengage if you keep pressure on the controls. Sounds like you have a hardware trim axis that is not being set to zero before you're engaging the AP.

It's usually a good practice to consider yourself as a cause before pointing the finger elsewhere, honestly. It's not a fun exercise to engage in, but to err is human, and more often than not, it's not the plane causing the issue.

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Kyle Rodgers

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1 hour ago, scandinavian13 said:

It actually probably is. The real autopilot will actually disengage if you keep pressure on the controls. Sounds like you have a hardware trim axis that is not being set to zero before you're engaging the AP.

It's usually a good practice to consider yourself as a cause before pointing the finger elsewhere, honestly. It's not a fun exercise to engage in, but to err is human, and more often than not, it's not the plane causing the issue.

I did not say it was the airplane that was causing the issue, and NO it's definitely no me for I'm using the correct technique. You've also have missed the point. I already know that the real aircraft auto-pilot will disengage if you put pressure on the control wheel, but that is not what's occurring, although it has done this with the 747. It WILL NOT engage when I press the auto-pilot. I've also mentioned that I set the trim control prior to leaving the gate, and I've always done this, as well as in the 747. When I'm in the climb, I'm following the flight director bars, as I'm supposed to, and it's right on the money when I engage the auto-pilot. So, there is NO reason for it to not engage, unless something is wrong with my controller. I've calibrated and I don't see any problem with it. So, what else is there? The technique I've used is by the manual, so it's not human error in this case. You say it sound like the trim axis is not being set to zero, and that's what it sounds like to me, But as I said, I set the trim to the correct position prior to leaving the gate. How do I check to make sure the trim is set to zero as you say? The FMC gives a trim setting of around 5.5 to 6.0. Is there something that I might have ticked in the FMC menu options settings that could cause it? The only thing I can think of is my controller.

Let me mention this because this could play a part. I have the Microsoft Sidewinder Force Feedback 2. Will disconnecting the force feedback cable cause this problem? I disconnected it because I don't like the return to center force that occurs in P3D. If I use FSX, I don't have this return to center force but when I fly using the P3D, the joystick has the return to center force, which is not realistic in the real aircraft, not in a real Cessna nor the real 737.

Ken. 

 

Edited by kmanning

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1 hour ago, kmanning said:

How do I check to make sure the trim is set to zero as you say?

You have to check your hardware assignments in the sim to be sure the sim hasn't assigned an axis to a trim axis.

When you're trying to engage the AP, you need to have the plane trimmed to the point where you can let go of the yoke and it will continue in the same direction without you stepping in to correct it. No nose drop, no climb, no turns - in trim.

Alternatively (and less realistically), you can disable "realistic AP engagement," and set "ignore hardware when AP is on" in the PMDG SETUP > menu of the CDU.


Kyle Rodgers

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Check to be sure that you have enough "null zone" on your yoke.  It there isn't, it will disengage the AP.

Also be sure before you take off that you select (arm) a lateral control on the MCP.  Either LNAV or HDG.  If you don't the AP will go to CWS (control wheel steering).

Also check in the FMC PMDG Options to be sure that you don't have an autopilot option set that would make it harder to engage.  I like "Realistic Autopilot" buy you might want to try to turn that off and see if it helps.


Robert Yunque

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Ken,

There are thousands upon thousands of good folks hanging around here who can help you with any problem you might ever conceivably have.

Simming is a hobby.  Emotion should never play a role in it. 

If you are having trouble getting something to operate- simply swing through here and say:  "I'm having trouble with ________"

You will get a ton of help.

 

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PLEASE NOTE THAT PMDG HAS DEPARTED AVSIM

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Do you have this issue? 

 


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16 hours ago, scandinavian13 said:

You have to check your hardware assignments in the sim to be sure the sim hasn't assigned an axis to a trim axis.

Hi Kyle,

As far as I know, I don't think another assignment is using the axis for the trim. The only one I've made changes to are the ones assigned by the FS2Crew for the PMDG 737NGX. I'm using the C and F keys.

Quote

When you're trying to engage the AP, you need to have the plane trimmed to the point where you can let go of the yoke and it will continue in the same direction without you stepping in to correct it. No nose drop, no climb, no turns - in trim.

Let me be sure I understand your answer because it doesn't quite makes sense to me. When you said "No Climb." did you mean no pitching of the nose, because when the airplane is taking off, it's in the climb. I don't press the auto-pilot button until I've achieved a constant pitch, following the flight director bar, and when it's fixed, I then press the button. I agree with you that I would have to have the plane trimmed to where it maintains the same direction it's going. But when I set the trim prior to leaving the gate that's given by the FMC, is that exactly what I'm doing, setting the trim for this take-off pitch? And when the flight director bar is fixed, its it not trimmed to the point where the auto-pilot should engage when I press it?

 

Quote

Alternatively (and less realistically), you can disable "realistic AP engagement," and set "ignore hardware when AP is on" in the PMDG SETUP > menu of the CDU.

I think I would rather use the more realistic setting. I'm begging to think that the problem is in my controller.

Ken.

Edited by kmanning

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16 hours ago, signmanbob said:

Also be sure before you take off that you select (arm) a lateral control on the MCP.  Either LNAV or HDG.  If you don't the AP will go to CWS (control wheel steering).

I've never had it to go to CWS. It would just never engage when I press the auto-pilot button. But I do need to check the null zones to be sure they're not tight. They should be fine because I've never moved them, and should be set at their default.

 

16 hours ago, signmanbob said:

Also check in the FMC PMDG Options to be sure that you don't have an autopilot option set that would make it harder to engage.  I like "Realistic Autopilot" buy you might want to try to turn that off and see if it helps.

I prefer the realistic.

 

Ken.

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42 minutes ago, kmanning said:

But when I set the trim prior to leaving the gate that's given by the FMC, is that exactly what I'm doing, setting the trim for this take-off pitch? And when the flight director bar is fixed, its it not trimmed to the point where the auto-pilot should engage when I press it?

No, you need to use trim after takeoff so the aircraft climbs at the same pitch that the flight director indicates without any input from you. You should be able to take your hands off the controls and have no pitch change. At that point the AP should engage without issues.

Edited by BrianW

Brian W

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Ken,

The correct phrase here is that the airplane should be "in trim."  What we mean when we say this, is that you can take your hands off the controls and the airplane won't show a strong tendency to change pitch or roll from where you have it currently.

Obviously, if you are climbing, it will eventually lose a bit of airspeed and the pitch will naturally lower- but what we are talking about is that being "in trim" means the airplane is naturally going where you have it pointed currently- you do not have to hold control pressure to keep it on the desired pitch/roll.

Does that help?

 

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PLEASE NOTE THAT PMDG HAS DEPARTED AVSIM

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6 hours ago, kmanning said:

But when I set the trim prior to leaving the gate that's given by the FMC, is that exactly what I'm doing, setting the trim for this take-off pitch? And when the flight director bar is fixed, its it not trimmed to the point where the auto-pilot should engage when I press it?

I think there's something you're getting confused here. Setting your trim for take-off is exactly that, setting it JUST for take-off. Once you're airborne, you need to set your trim accordingly, and for that, you don't even bother looking at the trim indicator anymore. At that point, you just go based off of feel. Once the plane is maintaining the desired pitch without you having to maintain directional control (in other words, the plane will fly at the pitch you want even with your hands off the controls), you're in trim.

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Captain Kevin

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1 hour ago, Captain Kevin said:

At that point, you just go based off of feel. Once the plane is maintaining the desired pitch without you having to maintain directional control (in other words, the plane will fly at the pitch you want even with your hands off the controls), you're in trim.

Hi Kevin,

I see where you're coming from. Since you say that I would go by the feel of pressure of my joystick, I would trim it so that it will be in trim when the joystick is in it's center position. But my joystick is not set for return to center position. In other words, there is no pressure. It moves smoothly as in the real aircraft when you move the yoke.

Ken.

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4 minutes ago, kmanning said:

I see where you're coming from. Since you say that I would go by the feel of pressure of my joystick, I would trim it so that it will be in trim when the joystick is in it's center position. But my joystick is not set for return to center position. In other words, there is no pressure. It moves smoothly as in the real aircraft when you move the yoke.

No, that's not quite what I meant. Basically, if you're still having to move your stick just to maintain the pitch that you're trying to maintain, you're not in trim. If the plane's flying the desired pitch even with your hands off the controls, then you're in trim. The main point being that after take-off, you can ignore the trim indicator. The trim you set for take-off is just for take-off. After take-off, you trim the aircraft as necessary.


Captain Kevin

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Air Kevin 124 heavy, wind calm, runway 4 left, cleared for take-off.

Live streams of my flights here.

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Ken,

the Boeing yoke has a center position. It‘s returning there when the elevator tab returns to its center position. Trimming an airliner isn‘t made by trim tabs on the elevator but by moving the whole stabilizer. Think of the stabilizer as a wing that is mounted vice versa. It holds the tail down so the nose doesn‘t drop. Moving the elevator now changes the profile of the „wing“, like flaps. So all you do for takeoff is setting an angle of attack of the stabilizer that neutralizes the weight of the nose at Vr. And that’s what you do in flight too when you trim the airplane. 

In case of your sudden autopilot issue... have you tried using the default panelstate? 

Edited by Ephedrin
Some wrong words

,

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