I tried a search for this specific issue, and I just need to check that I am not crazy in seeing this behavior (which I think is a bug)...

In any of the G1000 aircraft (yes, running the WT NXi mod from the Marketplace) and also any of the steam gauge aircraft with the default traditional autopilot: when engaging the AP in a climb and having no other vertical modes selected, the autopilot seems to default to ALT mode and violently checks the ascent to get back to whatever altitude you were when the AP was engaged. My understanding of at least the G1000 (but also the type of generic steam-gauge autopilot that is being modeled) is that the autopilot should default to PIT mode when no other vertical mode is commanded in the flight director.  In other words, you should be able to establish a manual climb to say 10-degrees nose up, and if PIT is indicated on your instrument then the aircraft should hold that pitch angle upon engaging the autopilot, until/unless you have commanded one of the other vertical modes (ALT, FLC, etc).

My questions:

1) Am I correct that the default mode should be PIT, not ALT? (I know the G1000 manual says it should be PIT)

2) Is everyone else seeing the same behavior?

I figured this would be well known and I would have found posts on this via Google, but I don't see anything about this specifically (there is lots on crazy AP going into dives and such, but this is not that). Want to get confirmation before I file this as a bug with both WT and Asobo.

The reason this is important is that it forces you to preselect either FLC mode or VS mode with a preselected climb rate, which I understand is not realistic and wouldn't necessarily be forced SOP in the real world.

I haven't checked all of the aircraft, but my brief survey with the Cessnas, Beechcrafts, etc all show this behavior.

Edited February 24, 20224 yr by PurdueKev

1 hour ago, PurdueKev said:

Is everyone else seeing the same behavior?

The WT G1000NXi defaults to ROL and PIT for me. ROL and PIT are the default AP lateral and vertical modes respectively for the few GARMIN autopilots I'm familiar with.

The steam gauge C172 autopilot seems to default to ROL and VS.

Al

57 minutes ago, ark said:

The WT G1000NXi defaults to ROL and PIT for me. ROL and PIT are the default AP lateral and vertical modes respectively for the few GARMIN autopilots I'm familiar with.

The steam gauge C172 autopilot seems to default to ROL and VS.

Al

Are you sure on the WT NXi?  I just tried it, and I am absolutely certain I am getting ALT mode when I hit the AP button, even when I have PIT showing on the annunciator.  This is for the Bonanza (both default and the modded) and the C182.  Which planes can you confirm this on?  I haven't been through everything that uses the NXi, so maybe it is aircraft specific.

7 minutes ago, PurdueKev said:

Are you sure on the WT NXi?  I just tried it, and I am absolutely certain I am getting ALT mode when I hit the AP button, even when I have PIT showing on the annunciator.  This is for the Bonanza (both default and the modded) and the C182.  Which planes can you confirm this on?  I haven't been through everything that uses the NXi, so maybe it is aircraft specific.

I have also noticed that ALT mode can be persistent... which is a bug, I believe.

When you turn off FD, ALT mode should be scrubbed, but yet, if I turn FD back on, ALT mode is often there.

What I do, is when turning on FD, check for ALT, and if it is active push ALT to turn it off.

38 minutes ago, PurdueKev said:

Are you sure on the WT NXi?  I just tried it, and I am absolutely certain I am getting ALT mode when I hit the AP button, even when I have PIT showing on the annunciator.  This is for the Bonanza (both default and the modded) and the C182.  Which planes can you confirm this on?  I haven't been through everything that uses the NXi, so maybe it is aircraft specific.

As a simple test I loaded the DA-62 onto a runway and turned on the AP -- result was ROL and PIT. Same for the C172 and Grand Caravan. Used the WT G1000NXi in all cases. Maybe being airborne leads to a different result?

You might try seeing what happens with a default a/c if you empty the Community folder of any addons. And be sure you don't have any old G1000 mods in the Community folder.

If you try my simple test above, what do you get?

Al

Edited February 24, 20224 yr by ark

Did another experiment. Took off in the DA-62 with the WT G1000NXi and at about 500ft up turned on the AP which went into ROL and PIT modes with ALTS armed (white letters).  It continued the climb in the ROL and PIT modes and eventually captured the altitude that I had set at the top of the altitude tape at which point PIT changed to ALT.

Al

Edited February 24, 20224 yr by ark

Never heard of PIT mode but the default KAP140 defaults to VS mode and is supposed to capture the extant VS when activating the autopilot. It doesn't, it behaves like the OP describes. You can fix it with a bit of tap-dancing if you have one of the programming add-ons. I used SPAD.neXt., as shown in this video.

 

Well I figured out what is happening, at least for NXi-equipped aircraft (I tested in the C172 G1000 as well as the DA62), though I am not certain if it is a bug or if it is supposed to work this way:

- if you engage the flight director prior to engaging the AP (either by clicking FD or another mode like HDG or NAV), the AP will indeed default to PIT mode if you haven't set a vertical mode, so that works like real-life;

- however, the pitch angle is set at the moment you activated the flight director, not the moment you engage the AP;

- if you haven't pre-selected any mode in the flight director, when you click AP then indeed ROL and PIT are displayed on the annunciator by default and your roll and pitch angles will be set at the moment you engaged the AP.  So the behavior is just as Ark observed: you can start a climb, engage the AP and the aircraft will hold the pitch and roll angles by default until you select other modes.

- But, if you click FD or, say, HDG or NAV (in case you want to initially follow a runway heading for example) while still on the ground, the pitch angle is set at whatever your nose attitude is while sitting on the runway! So, when you do engage the AP, the flight director will try to deliver the pitch angle you had when you activated the flight director command bars (which on the ground is basically level flight), not the pitch angle of the climb you are in. I confirmed this by checking the magenta command bars on the flight director while climbing before hitting AP - sure enough, they were pointing down, indicating the aircraft would pitch down to level flight as soon as the autopilot servos were turned on.

- What this means is that if you want to, for example, preselect a desired runway heading to follow with the heading bug before takeoff, you have to be careful NOT to click HDG while still on the ground without also commanding a climb mode in the flight director like VS or FLC - otherwise, when you click the AP on the plane will level off abruptly to the pitch angle that was set on the ground.  You can simply pre-tune the heading bug as desired but you have to leave the flight director off, so that the pitch angle initially followed under PIT mode is set as your nose attitude at the moment you engage the autopilot once established in your climb.

Some people might think that is all intuitive, but it wasn't to me. It especially means people who like to fly airliners, where you do typically engage the flight directors while still on the ground, can't do that in a G1000-equipped aircraft in MSFS. Someone who knows how the G1000 works in real-life would need to confirm if that is a bug or if it really is the way the real system works.

 

By the way, I also did observe that the default steam gauge autopilot indeed defaults to VS mode but does NOT capture the climb rate at the time you engage the autopilot. Instead, it levels you off at 0fpm as MarkDH noted, and there is no way in the MSFS unit to preset the vertical speed to anything other than 0fpm without all that SPAD programming. That is definitely a bug, or at minimum a gross oversimplification of the real-life KAP140 (which I know for a fact lets you pre-program the desired VS before engaging the AP while on the ground).

Edited February 25, 20224 yr by PurdueKev