Heading Hold still breaking LNAV 787 post SU13

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787 post SU13

Brief description of the issue:

Unable to engage LNAV after Heading Hold/select.Shows as armed but does not engage even afte disengaging AP.

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

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Detailed steps to reproduce the issue encountered:

Hot start on the RWY but cold and dark at the gate works too. Enter Flight plan and configure plane as normal. Set heading per departure procedures (22R @ EWR is 213). take off, engage Heading Select or Hold. works as normal. do Direct to a waypoint, engage LNAV but plane does not follow. Similar to this closed thread: https://forums.flightsimulator.com/t/hdg-hld-breaking-lnav/609189, After takeoff, i’m attempting a direct to GAYEL off the EWR4 departure

PC specs and/or peripheral set up if relevant:

Build Version # when you first started experiencing this issue:

SU13 (1.34.16.0)

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Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

If relevant, provide additional screenshots/video:

2

Can confirm this has not been fixed and was a bug in SU13 beta that I reported while in beta.

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i had the consideration about 5 minutes ago it’s an EWR problem. I did a flight from JFK>FRA last weekend and lnav worked just fine. iirc i engaged heading hold for a couple of seconds to get the next waypoint queued up and lnav worked fine

Do you have the payware EWR by chance? wondering if it’s that (which would be really really weird)

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I will need to dig through some manuals and investigate this further, but could you please try this same scenario, but instead vector yourself onto a closer intercept heading to the direct for GAYEL? I have a suspicion this isn’t actually a bug, and is moreso that you are trying to insert a direct and engage LNAV when not on an intercept heading.

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unfortunately there is nothing closer on that particular departure; you are vectored almost immediately after take off, which is typical for the EWR4 departure. ATC will then move you around and clear you to the next waypoint as they see fit. Not being on VATSIM this time around i’ll just usually vector myself or, in this case, just direct to the next waypoint and flip a yooie if i need to which has worked in the past.

When i attempted to recreate the issue (via hotstart on the runway) prior to making this post, i thought it was a similar thing that you needed to be heading in the relatively same direction as the next waypoint in order for lnav to properly kick on, and that makes total sense. I did the direct, changed my heading bug to approximate intercept heading but still would not disengage heading select after pressing the LNAV button (which should correct me back to the magenta line)

That said, it’s entirely possible that even after completing the turn from 213 to interceptish, that i’m still too far offset from the path laterally. So i might be headed in the same direction as my waypoint, but i’m too far left/right of the magenta line for it to pick up. There is still a sort of window that will allow the plane to self-correct your course and it’ll just kinda weave it’s way to a straight line along your flight plan. Unless this has been fixed by WT lol

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There is a discussion as recently as this morning on the Working Title Discord about issues with the EWR4 departure, possibly a combination of how some of the nav data is coded and interpreted that breaks LNAV in this particular case. I’m guessing this is all related.

A WT dev mentions they are considering adding some fall-back modes to handle these uncommon cases.

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I do. It also happened at EWR. My problem occurred when I took of 4L. Went on the EWR4 Departure. After flying manually 060 then turning to 310 after the TEB 4.0 DME I selected HDG HLD to just hold my heading for a few seconds while I engaged the FMS to go direct GAYEL. At that point it would no longer make GAYEL active. It would not allow me to make it direct as it made it the past waypoint on the FMS. Instead of it making it a direct to, like the normal logic happens.

I do own Drezweicki Design KEWR.

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Same here. I had a theory that some devs will fix navaids if they’re wildly inaccurate or broken or whatever and it could have been borked during that process. I’m going to uninstall it and try again. At least then we can confirm it’s not a payware issue and can be narrowed down to GAYEL not functioning properly or the SID is busted for the 787.

Because i flew the plane just fine outta JFK/22R with the 787 on saturday basically doing the same maneuver and look:

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Flew runway heading for all of 10 seconds, went direct to MERIT and the plane flipped a yooie like it had somewhere to be (ignore the random line cutting across. This pic is from my VA PIREP lol)

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Yup. Same behavior without DD EWR. I should have started turning the second i hit LNAV and i did not.

I reloaded and flew the whole yooie by hand and engaged lnav after. It actually kicked my throttles back to TO/GA mode and did not follow the lnav. I think Newark 4 is broken at this point lol for the 787.

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It’s not really that heading hold is breaking LNAV, but that something in the Navigraph coding for EWR4 makes our path vectorization solution come up with very large XTKs for that part of the leg and so it never thinks it’s close enough to go from armed to active. We have a bug logged but no concrete solution so far.

You can just go direct to the next fix though and get nearly the same flight path, though, once you’re doing flying the runway heading.

11

I can’t entirely agree. It’s impossible after the error occurs to go directly to anything after that. The lateral navigation leaves the building with the exception of the heading select after that.

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Okay but thats what i tried the 3rd time around though. I selected the next fix on the flight plan and lnav did not engage and left me at heading hold. Not just GAYEL but some along the Q812 as well

My route was DCT GAYEL Q812 SYR DCT 45N079W 50N088W 55N097W DCT YSF DCT
YZF DCT 65N124W DCT GOATS DCT 67N150W 66N160W DCT ROCET R338 NATES
R220 NANAC Y810 OLDIV Y809 SUPOK SUPOKN. I attempted direct Gayel, and several fixes along Q812 but lnav did not engage one bit to any of those fixes. If anyone wants to try the above flp and see if they can get a direct go for it.

Don’t get me wrong. It does work the way i want it to work. Just not out on the EWR departure. And frankly saying the polite equivalent “yeah that’s not us” doesn’t inspire confidence the issue will get resolved. Whether it’s WT or Navigraph or Asobo is the one who has to fix it i don’t care. All three companies are on the same boat so why not work with each other instead of blaming others?

I have a hard time believing it’s solely a navigraph issue, otherwise other planes payware or otherwise would have similar issues on the EWR4 departure; I departed monday from EWR in a 739 heading south from 04L and was able to do the yooie without issue. Same departure, DIR BIGGY and bingo bango i’m on my way to CLT as the plane executes a beautiful 180 degreeish turn. Were the issue a navigraph issue, the 739 would have a similar problems grabbing the path and following it

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I think you’re assigning malice where there is none, and I don’t think that tone is warranted. It’s only that we’ve only observed it with folks using their data, which is a data point for us to share to everyone so that folks can either confirm that’s true or not for their particular case. It’s important for us to get as much diagnostic feedback as possible for any particular bug so we can try to have more success in reproducing the issue. If someone goes, “actually, no, I have stock data and it does it for me too” that’s a very important data point for us to note as the coding between the procedures is not the same in both datasets. It’s not about finger pointing, and it’s unfortunate that folks would jump immediately to that conclusion.

As we already mentioned, it’s something that has been logged and is under investigation, but we don’t presently have a solid repro on our end, cause, or solution at this time. But we fix all sorts of path vectorization cases in each update so hopefully this is one of the edge coding cases we can resolve.

15

Just for kicks and grins i tried the same flight EWR>NRT in a 748 and the issue persisted. I engaged heading hold and heading select and was unable to engage LNAV properly. Same issue as the 787.

I was able to complete the RNAV Departure PORTT4 without issue. finally i’m on my way to Tokyo :rofl: :sob:

17

After pressing LNAV and in autopilot, due to a change of course I pressed the heading select button. After correcting the course, the Heading Select indicator could not be turned off and the LNAV never became active. I tried turning the autopilot of and then on but that did not work, also the approach button did not override the heading selection.

18

I just had this same problem in the Horizon sim 789. I departed on the EWR4 and was vectored by ATC. When I attempted to go direct MERIT LNAV stayed armed and would not engage even if I pointed the plane directly in line with the mgenta path.

2 Likes
19

I also had the same problem with the EWR4 departure while flying both the Horizon 787-9 and default 787-10.

Departed 22R, engaged heading select mode, then Direct GAYEL and LNAV and plane remained on Heading Select.

It was the EWR4 departure causing it. I tried the flight again but without entering a departure procedure. Departed, engaged Heading Select mode, then Direct GAYEL and LNAV. The plane went from Heading Select to LNAV and flew normally.

I’m grateful for this thread and those that have identified the cause. I just wish I had discovered it 2 hours earlier! :slight_smile:

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the RNAV Departure works fine if you don’t mind that. A bit of a pain to vector around after that but at least you can get on your way

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I don’t think this problem is limited to KEWR departures. I’ve had problems with DIRECTs for a few flights now. Often when I try to go direct-to a waypoint further down the flightplan LNAV breaks - highlights next waypoint after the one selected and LNAV disangages. After that if I try turining it on it just stays in armed state.

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I cannot get LNAV to work after using HDG select. I departed from KEWR 04L. Very annoying. Any clue how to get LNAV back? I am still enroute to Bermuda. Also I noticed my Distance to Bermuda TXKF is increasing instead of decreasing even though I am flying in the correct direction and half way towards the aiport from Newark. It almost seems something is running backwards on the FMS. Hand flying the approach but very bad bug that you cannot lock onto the Magenta Line with LNAV any longer.