This is something I’ve recently discovered and it might be something others have already realised but When I engage the Vertical speed A/P after takeoff the plane always rocks back and forth and I would try to manually control the vertical seed until a speed of about 270-290 IAS to avoid this rocking motion but I realise now if you engage the A/P VS as you retract the flaps you can avoid this rocking motion.
if you mean that when you engage the v/s your plane rocks then all you have to do is add / remove trim until theres no purple line left and itll work like a charm. PM if you need more help :)
I’ve tried that before but it seems to never solve the problem for me
Slowley adust it (addint 1% at a time until it removes the purple) and when theres none engage v/s.
it might also be that your engaging the AP at to slow of a speed for the weight your at. also, what aircraft are you using ??
I agree, usually the rocking is caused by a weight and speed issue. I always engage the AP a few minutes after take off.
Um, if you Click the ALT button, if you have a preset Altitude, it shouldn’t rock back and forth (from my experience)
I mostly fly the A350, 777W and 787 family and when I do engage the A/P it’s usually around 240 to 280 IAS
I set the a cruise altitude at the gate but when I engage the A/P later in flight I still get the same problem
Oh. Did you Click the V/S or Alt?
About the trim: purple up need + or -trim?. Purple down + or- trim?
Just move the trim even + or - and once its made the pruple go engage v/s and alt and you should be good