APPR Overcorrecting

Hello! My problem is that when I engage the APPR mode with any aircraft (but lets use an A320 as an example), at a nice speed (give or take 150 kts, light - medium load) and the aircraft levels off, decending at a stable rate, max 2 degrees roll. Thats fine but as I near the runway, the aircraft starts overcorrecting and eventually oscillating with pitch in excess of 40 degrees from the horizon line. I’ve looked at all the tutorials that have been recomended to others with no luck. Does anyone have a clue on how I can fix this?

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Do you have your aircraft correctly configured? Asking because you don’t mention flaps in your original post.

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Flaps full, Gears down and spoilers armed @Aceorbit

I’ve also experienced near identical situations as you’ve described. My solution is that I engage the ‘NAV1’ autopilot mode first. That way, the aircraft should align knowing that you must be in control of the vertical rate of descent.
But I don’t always do that, so I press the ‘Appr’ button. I find, too, that the plane will ascend and descend violently. In which case I should take manual control. I find also that if my speed is reduced then I won’t often get the reaction as I’ve just described.
Hope this helps!! 😃

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Ah, that makes a bit more sense. Ill try that now.

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As i know; if your speed before glide slope interception is low; the aircraft will start to pitch up and down violently… My protocol: before interception; stay on 180 knots. When the GS marker is descending, start decreasing your speed to the approach speed according to your load… By implementing this; I haven’t experienced this issue anymore…

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Switch to Nav 1 before enabling appr.

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If you could share your replay that would help us figure out why that is happening. There are various scenarios that run through my mind but don’t want to guess.

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I know! That’s a pretty common and known issue when it comes to APPR. There’s nothing much to do other than just hand fly it.

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Similar incident happened to me around 53:30 then i ended up taking control at 54:30

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Definitely acts strangely with APPR on.

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Do you know what speed you were at when you set flaps full?

One issue I can see is that Mexico is at 8Kft, so your ground speed is much higher than what the Appr Mode is tuned to so some of the parameters for the AP may have to be tweaked for higher altitude.

I would also suggest putting the plane in landing configuration earlier so it has time to correct for the increase of lift/drag due to flaps extension.

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Final approach air speed was around 145 kts, but i will try setting it earlier and see what happens

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150 knots in an A320? Try 130-135. The A320 also has been been a little iffy when it comes to APPR mode since the rework.

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Had it happen with 777-200LR flying into denver but plane violently overcorrected horizontally

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I’ll try that.

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The a321 has a bad oscillation problem which hasn’t been addressed for a while; didn’t think any other aircraft have this bug tho…
I intercept at 3500 ft AGL, 11mn out @ 190 kts IAS

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