Can't follow flightplan using NAV mode/FMS source

[Regis9]

Hello, as per the topic title. I program the flightplan into the FMS, when airborne and on an intercept course select the autopilot NAV function, select FMS as the NAV source on the PFD, FMS is inficated on the PFD as an active mode, however the aircraft ignores the flight plan routes and acts as if there is no laternal navigation mode selected. HDG mode works fine. I have the sequencing options set to auto in the CDU legs page.

Is there something else I'm missing?

[jarek]

It could be that you are too far from desired course, flying in opposite direction, having vectors set in FMS for current leg etc etc... It's hard to say without detailed description and working on particular scenario.

[Regis9]

In the multiple attempts I’ve made I’ve been within a few nm of the course (and actually flew past the desired course line), flying in the direction of the course no more than 30 degrees difference from the course heading.

Active waypoint in the FMS is the next waypoint, no vectors.

[doodlebug]

If you give us the exact details (flightplan, intercept etc) we will try to replicate the error.

[Regis9]

Sure, first flight was KHAF-KMRY, direct. Departed KHAF RWY 12, used the HDG mode to give me an intercept course, arm FMS mode, which showed active, but the aircraft just flew past the course line.

Second flight (which I've now tried three times) was KRNO PVINE HALLE WNDEL LMT KLMT. Departing 34L you are just east of the course after takeoff, I set a heading of 305 and attempted to intercept. Armed FMS, which flashed, then showed solid, the aircraft started drifting to the left (at which point I took the screenshot below). It looks like the FD is telling the aircraft to start turning right to intercept but the aircraft does not do it.



On all of my flights except the last one I had CDU legs page set to auto sequence. I got a suggestion at avsim to set CDU legs sequencing to inhibit on the ground then set to auto once airborne. I tried that but no improvement.

[Taguilo]

Hi,

I'm sorry I cannot see what's going on in your pic as it is too small. Can you post a set, perhaps within a zip, so I can check your config?
I think you must be aware that NAV mode, after so many months (and testers) being check, must be working fine
However, it might be possible that a specific config combination must have trouble. That's the reason for us to recheck.

Thanks
Tomas

[kasten.amarant]

i Had the same problem in my last 2 flights. Ill try to bring more info when i make another flight.

My flight was 2 times KSEA-KPDX. After departure i used dirTo next waypoint and activated NAV and the autopilot. It went to the next waypoint but right after it it went straight ahead instead following NAV. FMS was selected source and shown in green, solid. After every waypoint i again used dirTo, and every time it did it just to continue straight ahead after the wp was reached. Could be i did something not right but tbh the manual doesnt tell many things. Is that the only tutorial out there?

Like said, ill try to make a vid or something next flight.

[Taguilo]

Ok, what you told us is important. Problem occurs when you select DIR TO right?

I will let it checked.

Thanks!

Tomas

[N4GIX]

Doesn't using DTO suspend following the remaining legs on a flightplan? Or am I all wet?

[KenG]

Doesn't using DTO suspend following the remaining legs on a flightplan? Or am I all wet?

No, you can DTO to any point on the FPLN and it will continue to follow the FPLN.

[N4GIX]

No, you can DTO to any point on the FPLN and it will continue to follow the FPLN.

Thanks Ken. I must have been thinking of the UNS-1 which is the only FMS I have any familiarity with... not much to speak of!

[Regis9]

Hi,

I'm sorry I cannot see what's going on in your pic as it is too small. Can you post a set, perhaps within a zip, so I can check your config?
I think you must be aware that NAV mode, after so many months (and testers) being check, must be working fine
However, it might be possible that a specific config combination must have trouble. That's the reason for us to recheck.

Thanks
Tomas

Sorry about that, usually when I post from Imgur there's an active link for the larger picture. Happy to send this and more pictures along.

I'm fully confident I'm doing something wrong, some little detail specific to this aircraft...that's what's driving me nuts!

I should add, when in NAV mode I can freely roll the aircraft using the yoke, unlike when I'm in HDG mode.

[Regis9]

File attached with photos, first is the one I tried to upload here, second is a series from my last attempt, same flightplan.

[Taguilo]

Thanks.

Are you using FSUIPC to control aileron axis ?? That might be the problem, best guess

Tomas

[Regis9]

Did a bit more testing, I don't use FSUIPC for Aileron control as I have a Brunner CLSE-NG yoke and the Brunner software directly controls the aileron and elevators axes. I tried disconnecting the Brunner software and enabled the yoke using P3D axes assignments and it now works and will follow the FMS course.

It's not a great workaround as now I have no force on my yoke. My question is why the yoke inputs would impact the ability of the aircraft to use NAV mode? It's not as if it's moving and causing the autopilot to disconnect, there's no evidence of that and I can use HDG mode no problem...not sure why the difference interaction between yoke and autopilot in NAV mode?