Autopilot should sync to current VS (or PIT) when engaged. Not to 0 fpm

[JuiceBox7535]

Brief description of the issue:

When turning on the flight director or autopilot, the vertical mode should sync to the current vertical speed.

For example, if you turn on the flight director using the VS key while in the climb at 2,400 feet per minute, it should come up with 2,400 fpm selected, not 0 fpm. (It should also sync again when you press AP to engage it). Same thing if you engage it in PIT and ROLL mode. It should come up initially at the current pitch and bank angle. Not roll wings level, 0° bank.

Provide Screenshot(s)/video(s) of the issue encountered:

Detail steps to reproduce the issue encountered:

Establish a climb or descent, and select VS and engage the autopilot. It should not command a level off.

ZenDesk Report Number
19115

[SaratogaPilot87]

That depends on the AP. Some of the older Century APs I have flown with would behave like the Garmin APs in MSFS and some of the later ones were more like what you are expecting.

I have only limited time in real G1000 equipped aircraft and I don’t think I ever used the AP so I don’t know what the real unit does if you don’t preselect.

In MSFS I hit VS before I engage the AP, set the climb rate I want and then activate AP and while there still is a slight dip it is not as bad as doing it the other way around.

[JuiceBox7535]

Hi @SaratogaPilot87, you must be a Piper guy! Some of those older Century autopilots were not much more than a glorified wing leveler. The bug I mentioned is in respect to modern avionics that are modeled in the sim. G1000/3000/5000, Collins Proline 21 and PL Fusion systems, etc.

I think there is a binding for a pitch sync button, but seems I recall it not working correctly. (And shouldn’t have to press it anyway)

[Norman999933]

Couldn’t agree more. What makes it more frustrating is because that’s how it’s supposed to operate, I always forget it defaults to zero, and have to madly change it afterwards.

[BTripleSeven]

Well, all the modes should engage on current parameters anyway and they don’t (heading is an exception). VS should engage on current VS at time of engagement, FLCH makes a big pitch change before recapturing the pitch at time of engagement. No difference should be seen while switching from VS TO FLCH and vice versa (at least in pitch).

[N6722C]

Its not clear from the AP manual, but while it states that the AP should capture the current VS, I cannot believ that tehre are not limits.

ie If theh plane is in a deep dive of -5000ft/min, would you really want the AP to engage ???

Similarly for a steep climb , that the plane could never hold for more less than a minute at full power, without stalling.

[JuiceBox7535]

Yes, there are always limits. 5,000 fpm isn’t out of the question for a turbine aircraft. Typically the limits are based on airspeed. If you select a crazy high VS, many systems will attempt it until the airspeed approaches red line, then it will go into an FLC speed protection mode (FLC OVSPD). Some also have low speed protection as well. But I think the basics of syncing when you engage it should be the first priority.

[N6722C]

I agree … I Modded my APs months go to capture the VS, and submitted a ticket to Zen Desk, but lets face it, correct AP operations is less “popular” to have fixed, that a “Press any key to Continue” cosmetic issue, or the occasional building that is the wrong height,

So rather than get frustrated with the issue, and Asobo, I just “fixed” it as a mod and moved on… MSFS with the Community folder is just “unimaginable” !!

The set VS when AP is turned on is just one simple line of JS, placed in the correct place.

Same goes for the AP Baro Reference mix ups.

[BTripleSeven]

Based on my experience as airline pilot I want the ap to engage at crazy VS during a descent, especially if it is an emergency descent. Then in will switch to flch because I want to go red line on speed. Crazy VS on climb? Unless I do a ferry flight with 2 time 114000lbs on thrust= yes.

[N6722C]

Thanks for that insight into the descent VS.
Considering the descent VS in a smaller GA plane, like the C172 (without flc, or flch) then maybe the max decent VS should be something that can be achieved, as an emergency decent, without overstressing the plane …

BTW: Interesting Bio… for a moment I thought I had clicked on the wrong place and was reading my own !!! (well – almost )

[BTripleSeven]

The thing that I do not like in the simulation is that the airplane is destroyed at VMO-MMO-VNE. This is incorrect since in aerospace everything is built with a safety factor (factored landing distance, factored G tolerance clean, dirty…) Into level D simulation we have put the limits slightly above VMO MMO to reflect that. On modern jets, you have the envelope protection kicking in plus the warnings to alert the crew.
For GA airplanes where you have control over the prop pitch, it makes sense to have aggressive VS in descent since you use the prop to “airbrake” , was doing that often with “my” Kingair, practical, especially into the Alps.

[N6722C]

Thanks … so for say the 172 with fixed pitch prop, maybe the max VS should be that that reaches the end of the yellow arc, with power at min, clean config – or maybe just what the VS gauge extends to ?

edit

Which seem to be the same – How about that !!!