JS41 - FMS - LNAV guidance

[NoahBryant 26]

I think I'm going to give up. I'm not using the DEFAULT ATC OR FLIGHT PLANS. Meaning I dont set up any flight plan in flight simulator in order to use default atc. I dont know how you construed that I wasn't using the FMS, I assure you I am.OBVIOUSLY I am using a flight plan and OBVIOUSLY I am using the FMS. I didn't feel that I had to re-explain the entire problem when the original poster did it so exquisitely. The FMS active, the correct leg is active. The problem comes when I hit the NAV button and the plane starts a turn to the north and will not follow the flight plan, even if I am already manually following the plan and/or select direct to a fix. I'd be happy to send you my saved flight file so you can test it yourself.

[Paul_Smith 92]

I am sorry you are getting frustrated but I can only react to what you actually said, not what you meant to say. So when you said you knew about the DTO thing, and suggested it was not relevant because you were not using flight plans, default, ATC or otherwise, it is not exactly obvious that you are were, in fact, using flight plans and you had correctly setup the FMS. And yes, you do have to do the DTO thing every time you want the autopilot to start following the FMS in LNAV mode.Just in case this is relavent, the flight plan and flight mode are NOT saved. If you restore a flight, you have to set up the FMS again.

[NoahBryant 26]

Paul, I'm sorry, the semantics is getting pointless. The first thing I said was asking if anyone had a solution to this problem. Obviously I am talking about the problem that this post is all about, otherwise I would have created a new topic. When I start a flight from scratch, the problem doesn't occur. When I load my saved flight, the problem occurs about 80% of the time or so. When I brought this up a couple months ago, others suggested it may have something with the way that I load the saved flight. They suggested loading a default cessna first, shutting it down, then loading my saved flight, but this did not rectify the turn north problem.

[Paul_Smith 92]

Paul, I'm sorry, the semantics is getting pointless. The first thing I said was asking if anyone had a solution to this problem. Obviously I am talking about the problem that this post is all about, otherwise I would have created a new topic. When I start a flight from scratch, the problem doesn't occur. When I load my saved flight, the problem occurs about 80% of the time or so. When I brought this up a couple months ago, others suggested it may have something with the way that I load the saved flight. They suggested loading a default cessna first, shutting it down, then loading my saved flight, but this did not rectify the turn north problem.

Yes/No answer only please - when you load you saved flight, do you reprogram the FMC from scratch including selecting LNAV mode and using the DTO button to tell the AP to follow the FMC? If your answer is yes, could you please post a screen shot showing the problem.

[Guest JohnTK]

Hi brodie4598.I understand precisely the problem that you are experiencing as I have experienced it also. I think it is pretty clear at this stage that there is no fix for it other than to load a saved flight from a default aircraft and then reload the aircraft. Unfortunately this may require you to set up the flight from scratch everytime instead of being able to benefit from the panel state saved at the conclusion of your last flight. However, in my experience reloading the aircraft is the only way to guarantee that the FD will follow the route entered into the fms once nav is engaged. I am sorry that I cant offer you anything more helpful than the above observation. I just wanted to assure you that you are not alone in experiencing this particular difficulty with the JS41.Regards,John TK

[Guest Jimmatc]

Keith,The screens seem to have vanished, so I can't really tell what's going on. I do have one thought, however: is your left-hand "FCS CONTROL" switch set to pilot? This is the switch just to the left of and between your EADI and EHSI. If it's set to co-pilot your autopilot will do whatever's set up on the right-hand side of the cockpit (something pointing north perhaps!).Cheers,

[NoahBryant 26]

Yes - the FCS is correct. And I have also come to the conclusion that this is a bug that wont get fixed. Oh well.

[Guest BlueRidgeDx]

Well, you're not exactly giving us much to go on. You haven't explained what steps you've used to setup the FMS, you haven't shown any pictures of your FMA when the problem occurs, you didn't provide the route or procedure you're trying to fly, you didn't specifiy what A/P modes were in use before and after trying to capture the LNAV course, and you didn't sign your whole name.So instead of being a drama queen and declaring that PMDG doesn't fix bugs, maybe you should try being a little more forthcoming.

[docnobby 0]

Hi guys!I just ran into the same problem. I followed the procedures from the tutorial from cold and dark.If I start with the tutorial flight, the problem doesn't happen. However, when I start from a previously saved flightit happens sometimes.I know the solution would be easy: Load tutorial flight, set aircraft to desired airport, be happy!But I dont't want to do the complete startup every time, sometimes I'm landing on a airport just for short load/unload of 30mins.I don't shut down the aircraft compleatly. And I'd like to be able to save in those situations.Heres's a picture, wich I hope will give you a idea of what's happening:The left BRG rotary switch is set to LNAV, so the blue needle should indicate the direction to SONGI, wich it seems to do indeed.The autopilot and YD is on and set to IAS and NAV: CAP. From my understanding the autopilot should now try to fly the aircraft to SONGI. But instead it's heading straight north.Any iedeas what I might be doing wrong?Greetings,Norbert Caspar

[Guest BlueRidgeDx]

Hi Norbert,It's a little hard to say since the top of the EADI isn't in your pic (nice screenshot, by the way). Can you confirm which mode annunciators are displayed and what colors they are?The Bearing knob is for display purposes only, and doesn't directly affect the Nav Source used by the FD. Make sure that you've pressed the LNV button, and make sure NOT to press the V/L button.If it's not any of that, I'd try another "Direct To" SONGI, and if for some reason it STILL didn't work, try making sure you're on an intercept heading before attempting the DTO.Question: What exactly did the airplane do to get where it is? Were you heading North to begin with? If not, what was your original heading? What did you press, and at what point did the airplane start turning? Did the "FMA" on the EADI change modes at any point? Does it indicate proper course capture despite heading North, or is it properly indicating that the course has not been captured?I hope we'll be able to sort this one out for you.

[Yoda967 23]

In addition to what Nick posted (spot on stuff), make sure that this problem isn't something that got saved into your initial J41 situation. I've had this happen pre-SP1, but not since. The fix, for me, was to load the situation, and then IMMEDIATELY reload the aircraft using the FSX RELOAD AIRCRAFT command. Then, save the situation again. You can save over top of the existing saved situation.I've not been able to isolate why this sometimes happens, but it seems to be related to the save flight function.

Just want to reiterate what I said before. Try this and see if it helps. Generally speaking, once you've done this, you should be able to set up the cockpit the way you want it and save it again and it should be okay.

[NoahBryant 26]

The quickest thing to do is just reload the aircraft where it is. I went through so much trying to get this figured out. When you reload it (a lot) of the switches stay where they are and you dont have to do too much to get it back where it is. It's not necessary to go through all the trouble of loading the tutorial scenario.

[Yoda967 23]

Thank you, Noah. That's exactly what I've been saying.

[torro 0]

I have the same problem with the FMS heading NORTH when I don't load a flight plan in FSX. When I load a flight plan, in flight through the ATC screen the FMS turns to the correct heading as soon as I click ok to load the plan.Hope this helps.Ken Ockwell

[CaptKornDog 284]

I, too, have also seen this problem when loading a scenario other than a default aircraft or tutorial flight. Only way I could solve it is reloading the aircraft (and generally reprogramming the FMS/flipping some out of place switches).