Violent autopilot induced aerobatics. So frustrating [SOLVED]

Hi friends,

I really enjoy this game - until I have to engage the [word not allowed] autopilot :face_with_symbols_over_mouth:

I fly only small GA planes like the C172 and Carbon Cub. The following happens in those planes:

  1. I create the GPS flight plan, verify all is correct.
  2. The magenta line appears from departure to destination
  3. I verify that GPS is selected as primary nav source
  4. I take off and fly manually onto the heading and until the planned altitude (usually 3,500 or 4,500ft). All is well.
  5. I press the AP button.
  6. The airplane departs from controlled flight extremely violently. Like an F-16 it does a 120 degree wingover, points the nose down & screams towards the ground.
  7. Trim goes to full nose-down in 1 second.

Absolutely ridiculous that this game has not sorted out this most basic feature that FS2004, FSX, P3D, X-Plane 11 have working so well. I threw a lot of money at the Premium Deluxe. I expect these things to just work!

Or is it just me?? :sleepy: Is anyone else experiencing these? I have made sure I only use default airplanes.

I look forward to flying but now its got to the stage where I have to fly manually the whole way as I know pressing that AP button will ruin everything :neutral_face:

Any advice gratefully received! Back to resetting the flight and trying again :roll_eyes:

Thank you!

2 Likes

Flight model is set to modern?

1 Like

I did not know of this option, I will check now! I should disable it?

First of all, your Flight Model should be set to Modern. That’s in settings.

Second of all, what modes have you activated on the AP other than activating AP itself? Just because you press AP, it won’t actually do anything meaningful until you tell it to follow your flight plan and climb to a certain altitude (and by which method - VS of FLC)

It is set to Modern. AP modes activated:

NAV = ON
GPS = Primary source
ALT = 3,500ft selected
VS = +500FPM

When I press AP it slowly corrects towards the magenta line but this lasts only for 5 sec or so. Immediately after that the plane flips upside down, trim goes full nose down and its game over :sleepy:

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Sounds like you’ll need to add some deadzones to your controller, or recalibrate it.

I am gonna guess it has something to do with your controller. Some kind of binding or deadzone issue.

I would be glad to know too.

Normally I don’t fly aircraft with AP at all … Last week I put C172 at 2000Feet (no takeoff), with an arrival airport set somewhere. If you do that, the C172 is switching to Autopilot. If you don’t know that…

So what happens… I started to fly like I normally do… touch a key… and the autopilot started working against it. That’s normal. But you would expect small corrections, to keep you on course. It gently slides you back on track, at least I would expect a safe autopilot system to do that :cat: … take a few miles for the turn, etc. But instead it banked and dived like a madman left and right… whenever I tried to compensate manually - actually: disturb the AP - it would quickly go 90 degrees to the other side. In short, I crashed my 172, because I didn’t know at first, how to switch off the autopilot.

… until you click that little red button on the yoke of course :grin: but it took me 4 crashes and one forum topic to find the cause of it ! I posted some video’s here…

Personal observations:

An aggressive or high AoA with a low speed (i.e., some folks were still in the white zone on the ASI) can result in a departure as the AP is trying to reconcile both a decaying speed and a high climb rate. It could also happen if the calculated course is greater than 90 degrees off current heading, so a combination of some or all - low speed, high AoA, course change requiring maximum 30 degree banking, can result in an AP disconnect and subsequent departure.

For that, I try to trim for straight and level first, and have a generous margin of speed, before enabling AP. After I’m satisfied that AP is stable, then I’ll introduce a heading or altitude change, but not both together.

Yeah, I haven’t noticed such violent autopilot stuff. But I may be using the autopilot differently than you.

Why would it be the pilot’s fault. You don’t switch on autopilot while you’re diving or stunting around. It starts stunting around on its own, when you accidentally hit a control. At least that is what happend to me and I’m sure it started at horizontal flight, with proper airspeed. Default high takeoff via NAV-LOG will give you a straight and steady start.

I was replying to the OP, not you.

The AP “can” get into, what might be considered a Toppled state.
(Not that MSFS is purposely trying to simulate a Toppled AP gyro !! )

When this happens, the only way to “untopple” it is to reload the plane, which will also reload the AP.

Turning OFF the Avionics power, or the AP, even for an extended time, will not RESET the MSFS AP, once it has “BROKEN”

2 Likes

Opening was this,

Not really different from my case. The plane overreacts. AP is programmed to fly horizontally, so if you are going slightly up it sends you nose down in 1 second. It really happens, it is set too aggressive. Also when you touch the controls (my case) When you start up high with autopilot engaged, there is no AoA or direction issue. And when there is a direction issue, the correction should not be banking 33 degrees and turn 90 degrees within 10 seconds if I touch the yoke 1x. A C172 is not a Eurofighter,. Just try my procedure and see for yourself, it is unstable.

Let’s take a giant step back for a moment.
Autopilot is not actually derived from the two words you see. It is not a pilot, and it does not do anything automatically. In short it has no mind of its own and regardless of the things you said about it to your friends in the bar, it is not going to try to kill you.

The AP is simply a tool to control the aircraft based on the commands you give it. It is going to try to maintain safe control inputs to achieve the commands as best it can within the limitations built in by the manufacturer.

Unfortunately, like any tool, if used incorrectly, it can :warning:“cause severe injury or death” :warning:

Quick Lesson

Checklist for safe AP use…

BEFORE TAXI

  • Altimeter - SET to current field elevation
  • Flight Director - ON

Autopilot

  • Altitude Mode(ALT) - ARMED
  • Cleared or Planned altitude - SET
  • Vertical Speed Mode (VS) - ARMED
  • Planned Vertical Speed - SET
  • Heading Mode (HDG) - ARMED

BEFORE TAKEOFF

  • Auto Pilot Heading - SET to runway heading (do this when lined up)
  • Directional Gyro - SET to runway heading (do this when lined up)

TAKEOFF

  • Gear - UP (if equipped)
  • Maintain Runway Heading
  • Establish climb rate as selected
  • Flaps - UP (as required as airspeed increases to climb speed)
  • Climb Power - SET
  • Trim - SET to stabilize climb rate and airspeed
  • 500 FT AGL - AP - ENGAGE
  • When cleared enroute - Select NAV mode (or Adjust Heading Select to achieve a 30 degree course intercept. When autopilot has leveled the wings after establishing heading, Select NAV mode)

If using the TOGA feature of the AP, do NOT engage the AP until established in the climb as indicated by the Flight Director (usually about a 7 degree climb gradient) at that point select Flight Level Change (FLC) Mode and the AP will default to the current speed.

This is applicable to most small GA aircraft. Each aircraft will have its own requirements and this is by no means a definitive guide to autopilot use, but you should be able to safely use most available autopilots if you follow this simplified guide.

FYI
Be aware there IS a bug in the sim AP that will zero the selected VS if VS mode is engaged after the AP is active. This should not happen. The VS selected should default to the current VS when the mode is armed.

NEVER engage the autopilot until stable flight is achieved and ALL parameters are set correctly!

Remember, the autopilot is not an Auto Pilot. Do not expect it to recover the aircraft from poor airmanship. I do not recommend engaging the autopilot with flaps extended. If flaps will be required while AP is engaged make sure the aircraft is in stable flight without flaps before engaging the AP and gradually introduce flaps while the AP is active to allow the system to adjust safely.

6 Likes

Quite complicated, thx for the explanation ! interesting phenomenon

… and that would explain the opener’s issue ! aircraft going up… autopilot tries to force horizontal, but it overcompensates by elevator down. When it is consistent with my case (“manual override”), a sustained elevator down action. With the yoke touche a sustained aeleron in opposite direction. Because the correction seems to proceed, you’ll crash.

2 Likes

is it trimmed for straight and level before AP is enabled?

AP will lower the nose at times, likely in response to an out of trim status when it was turned on - a result if the previous action which was a climb. Watched it many times if I don’t trim upon reaching target alt.

The VS behavior is actually quite benign. By being zeroed every time, it forces a conscious decision to dial in a little or a lot of nose up/down. This is much safer than it automatically defaulting to the last VS setting - for example, if you had previously established a 1500 fpm descent, and you want to turn on AP while at 2000’ AGL.

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It isn’t supposed to go to the last setting. It should do exactly the same as FLC. When arming it, it should acquire the current condition. If I am at 145 fpm when I hit VS then it should hold 145fpm. All it is doing is changing the parameters of the PIT mode, allowing you to dial in a different rate after arming.

You do make a valid point about trim though. If the trim is way out then letting go of the controls is going to put the aircraft into an extreme attitude. Engaging AP is the same as letting go and it will take the AP a bit to dial in the trim. Just don’t. TRIM, STABILIZE, ENGAGE.

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Thank you all for your replies, im reading through them now. I took a short 37 second video to show you all what happens. This was a test flight. I made a flight plan. I took off but deliberately went off course a bit (as you can see from the GPS display).

The AP was set for:
ALT=3,500ft
GPS = Primary nav source
VS = 500 FPM

  • You can see that the first 20 seconds is normal flight, this is me flying manually.
  • All I do then (like I have done in all other flight sims like FSX & X-Plane 11) is engage the AP.
  • You can see what happens next. Instead of just a gentle turn towards the magenta it has other ideas :no_mouth:

Sorry for the quality, the quickest way to get this on here was to shoot it with my cell.

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I would add 2 more checks.

  1. Make sure AP is OFF during taxi or and again OFF before take off
    You may have turned AP on during an On-Ground Checklist, to perform some AP tests.

  2. (For MSFS only) - make sure that the Co-Pilots is not set to fly the Plane !!!
    Especailly when in the habit of having the Co-Pilot taxi to parking during your previous flight !

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