Howdy - lurk here often, but haven't posted until now...
I've been having this issue for some time now, but never sweated it much until learning how to perform ILS approaches. I'll take off, level off as per ATC, set the autopilot and switch it on. Eventually, I'll receive a new instruction from ATC and change the autopilot accordingly. I never have a problem with my heading, but the altitude response varies. Sometimes it'll climb/descend to what I specify, and sometimes it'll keep going. Am I missing something ridiculously obvious? This happens regardless of what plane I'm flying, by the way.
That is, indeed, helpful. In fact, thanks to you and that, I've just flown my best IFR performance to date. However, the initial inquiry is in regards to only the autopilot, as this behavior can occur at any time, IFR or VFR, ILS or not. It behaved on that last ILS flight, but I kinda had to trim-coax it to stay at FL190 initially. I understand that I can't expect it to do anything aerobatic, but I'm talking about a vertical speed of 1,000 - 2,000 fpm - nothing it shouldn't be able to handle. It'll calmly climb to the proper altitude and then just keep on going. Same for descents. I simply can't suss it out. Could possibly be a program glitch, and I could just uninstall and reinstall, but that involves reloading all the add-ons I've dropped in, and that's a project! Was hoping that I was just missing something obvious...Double and triple checked that only the altitude hold was selected during the problematic moments.
What AC and panel are you using? I have a thought on your problem, but need to investigat it a little before I give an opinion!
At the moment, the default settings apply (Cessna C172SP Skyhawk - default panel). Typically, I'll use either the Cessna or the included Learjet 45- again, with default panel. I have add-ons, but I'm not really using them right now.
You fly a Cessna 172 at FL190??? Man how did you get it up there? My real world skyhawk would find that a serious challenge.
As a thought, try the 208 Caravan , it seems to be a lot more stable, and I like it a lot... Nothing like the PT6 Turbine Yowza!
Well, I was referring to the Learjet at FL190, but I can't say that I haven't raised smaller planes to FL500 in the map settings just for fun 🙂