Why doesn't auto pilot work (at times)?

I have noticed at least twice in the past that the auto pilot in the Beechcraft King Air didn't seem to work and it has just happened again.

Here is the scenario -

Flight plan loaded (via load/save)

Flight plan verified in the G3000

Approach loaded in the G3000 and visually verified

On the auto pilot panel -

FD set ON

NAV set ON

YD set ON

Initial ALTitude set to 4500

VS set to +800

Take off

Gear up

Flaps up

AP set ON (altitude at the time around 1000)

The aircraft did NOT follow the flight plan and just headed around the same heading as the runway

The altitude continued to climb past 4500 even though 4500 was set and AP was ON.

I can't remember if I checked that the CDI was set to FMS but in the past I have never seen it set to anything else but FMS on startup.

Am I doing something incorrect or is there a problem?

Did you check in the PFD to see what the autopilot info said? It should show there that AP in On, Alt is selected and GPS is used for navigation.

Otherwise, it seems weird that it just didn’t work at all.

Thanks Tim.

I have also noticed that the aircraft doesn't always follow the 'lines' drawn on the map between my custom waypoints (which doesn't always link all the custom waypoints) BUT it always flies close to the custom waypoints. When I first noticed this it was a little off putting thinking that the autopilot (NAV) wasn't working until I noticed the aircraft flying close to those custom waypoints.

One think though which puzzles me is that the flightpath (between waypoints) doesn't always change to magenta as the aircraft in in that section of the flight path. The first leg is usually colored magenta and also the last leg before transition and then the legs in the approach - maybe that is the answer.

Thanks Tim.

 

I have also noticed that the aircraft doesn't always follow the 'lines' drawn on the map between my custom waypoints (which doesn't always link all the custom waypoints) BUT it always flies close to the custom waypoints. When I first noticed this it was a little off putting thinking that the autopilot (NAV) wasn't working until I noticed the aircraft flying close to those custom waypoints.

 

One think though which puzzles me is that the flightpath (between waypoints) doesn't always change to magenta as the aircraft in in that section of the flight path. The first leg is usually colored magenta and also the last leg before transition and then the legs in the approach - maybe that is the answer.

I'm not a real pilot but it seems like I see some real-world aspects to how MSFS autopilot works. Or attempts anyway. The "line" you refer to is the representation of a line between two of your waypoints. But your plane is not trying to fly on the line, it's trying to fly to the next waypoint.

I've noticed that when the waypoints require turns, the VFR screen attempts to show you curved lines to represent where the plane will probably go, but if you've zoomed in enough those lines are not accurate. Instead, the plane is only going to turn once it has actually reached the waypoint.

I'm not a real pilot but it seems like I see some real-world aspects to how MSFS autopilot works. Or attempts anyway. The "line" you refer to is the representation of a line between two of your waypoints. But your plane is not trying to fly on the line, it's trying to fly to the next waypoint.

 

I've noticed that when the waypoints require turns, the VFR screen attempts to show you curved lines to represent where the plane will probably go, but if you've zoomed in enough those lines are not accurate. Instead, the plane is only going to turn once it has actually reached the waypoint.

Thanks. That is what I thought but needed confirmation.

Regarding the 'drawn' flight plan and that parts of it are sometimes displayed in magenta. Consider the following image. When I took off this section was displayed in magenta as shown, after a few minutes as the aircraft was turning towards the flight path to intercept it, the line changed to white and then a few minutes later it changed to magenta again. After the aircraft passed the first custom waypoint that section remained as magenta and the next section remained white even when half from the first waypoint to the next waypoint. This happens much the same at the end of the flight, the last section changes to magenta but the sections already flown have never changed to magenta.

I am wondering what this (change to magenta) signifies.

Thanks. That is what I thought but needed confirmation.

 

Regarding the 'drawn' flight plan and that parts of it are sometimes displayed in magenta. Consider the following image. When I took off this section was displayed in magenta as shown, after a few minutes as the aircraft was turning towards the flight path to intercept it, the line changed to white and then a few minutes later it changed to magenta again. After the aircraft passed the first custom waypoint that section remained as magenta and the next section remained white even when half from the first waypoint to the next waypoint. This happens much the same at the end of the flight, the last section changes to magenta but the sections already flown have never changed to magenta.

I am wondering what this (change to magenta) signifies.

This could just be an MSFS bug, as it tries to simulate the real-world G3000 as best as it can. The theory is that the line should be magenta when it is the active leg of your trip. Once you hit a waypoint, the next line is supposed to turn magenta. In the simulation it may be that this just doesn't happen perfectly. (I assume it does happen perfectly in real life but I'm not a RL pilot so I have no idea).

MSFS still has a lot of kinks it is working out on autopilot, ATC, etc.