I’ve noticed some people having issues with the reaction of the A/P when it is switched on in various locations. Particulary some of the larger planes like the B747 B777 and the A380 tend to either suddenly drop or suddenly climb when activated. A good way of counteracting this is to figure what weight and balance suits you personally, and if you know which way the A/P will jolt the aircraft, use a minor amount of trim (5 or 10%) to counteract the jolt, it won’t fully stop it but it does help. Also a good idea is to Activate the A/P immediatly after takeoff to react fast, or wait until you reach about 8000ft. Because of a smooth climb the plane should react nicley. I do recommend easing off the runway then applying straight away. It really is about a planes weight and balance though so the best thing to do is experiment with both light and heavy settings. The reason the planes will bob up and down unexpectantly is because you may unknowingly still be pitching slightly up when you activate the A/P. In other words your climb rate is still increasing when you turn it on, and the A/P reacts to the exact ft/m the plane was pitching.
Confused? So am I slightly…
It will make sense when you start experimenting.
Also one more thing. PLEASE PLEASE PLEASE do not make the mistake of turning off the A/P without recalibrating your device, this mistake can ruin a perfectly smooth flight because you have mistakenly moved the angle abit, and when you come off, your heading toward the ground. Then when you try to lift, you stall. So always, when you want to turn off the A/P, calibrate your device, it helps alot and takes just 2 seconds.
Hope this is helpful to some people.