Violent +/- pitch after autopilot disconnect

My apologies if this topic has already been addressed in a previous post. I’m having issues with violent (drastic) + and/or - pitch after autopilot disconnect on approach. This seems to happen about 50% of the time, even if I have calibrated my device pre-landing. Extremely frustrating. Any suggestions? I would be most grateful. Happy flying everyone.

To fix this just make sure to calibrate before you disconnect

Just a reminder: There’s trim for a reason. Trim it until the purple is gone and you’ll see no more of that sudden jolting even when you calibrate beforehand.

I always forget lol

Thanks for your reply. I trim according to the official profiles posted here for all aircraft during takeoff and landing. I’ll test your suggestion and trim more aggressively. It might work.

Thanks for your message. I always calibrate prior to autopilot disconnect, but the issue still occurs. I hold my device in a neutral position (tilted forward slightly) just below eye level prior to calibrating - not sure if this has anything to do with the issue…?

Hi, I’ve heard about this “purple” with the trim before, but I’ve never been able to understand where the purple indication is? I’ve asked before with another post but not been able to get specific enough guidance… I mean exactly where we can see the purple trim indication… Could you please be really specific for me in explaining where to see this, thanks 😊

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Let’s take an example in the c172. Above the flap indicator you see the trim indicator.
When you start on the ground, this indicator reads 0. Moving your elevator up or down (tilting your device up and down), right of the 0 indication there will appear the purple indicator.
By dragging up or down you can change the value of the trim setting.
When dragging down you are trimming pitch up and visa versa.
In flight when the purple bar is above the center position, trim pitch down.(drag upwards i.e. decrease the trim setting) and visa versa.
Hope this helps.😉

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Thanks for your reply, Stef - Because I’m on a smaller device, the purple indicator is barely visible - a tiny dot next to the trim, but it’s there. I just noticed this. Thank you for your help - hope it works. Ciao!

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Thanks for dropping in. If you are flying on a small device (phone vs tablet), like I am, the purple indicator is barely visible. Mine appears as a tiny dot next to the trim % value. I just noticed this, thanks to Stef.

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Brian, take a plane of your choice and do a test flight.
Go to a comfortable altitude and engage the autopilot especially the altitude hold.
Once the flight is straight and level, try the trimbutton let’s say trim up maximum (100%). The “famous” purple dot next to the trim setting will grow when you trim. Now try the opposite to let the purple indicator disappear.
Disengage the autopilot and the plane should be trimmed out I.e. there will be no pitching up or down.

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Thanks, I’m on a phone so I’ll get a magnifying glass 😉… Sorry to be dense about this, but when you refer to the Flap Indicator and Trim indicator, are you looking at the virtual cockpit, like the representations of the real physical instruments in a plane? Or is it a digitial symbol on the screen like the trim contol button?

I’m referring to the trim control button above the flap control button

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Is there any chance of a photo to show this purple dot please…? 😊 I think I’m starting to understand that it’s in the cockpit near the trim wheel?

But then your other comment makes it sound like the digital control button where we set the trim…

And yes on a phone it’s very very tiny. When you trim there is a gap of the center position, when there is no purple bar and when it appears. This can be a difference of a few notches of trim.
For example. Let’s say the plane is completely stable with the trim on 0. When you start trimming it is possible to trim until 5 to see the purple bar.
Especially on small devices it’s not easy to see.

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No worries - I’m referring to the HUD, the default display, not the virtual cockpit. Yeah, you may need a magnifying glass! Like I said, it’s barely noticeable. Good luck mate.

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Thanks both, I’m going to fire up the Dash 8 soon, and trimming will be the first thing to be tested! So it’s the actual button we use to set the trim, the purple appears to the right to indicate a level of out of trim, and disappears when the plane is in trim…

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Maybe I forgot to mention that when trimming please hold your device steady! 😉

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Testing as we speak. On approach into Madrid. Wish me luck!

All the best! If you want I can come over and do tower and ground in Madrid so you can practice with a couple of t&g!

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