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Gary McCluskey

CMD & LNAV buttons won't light

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Hi

To load a flight plan, I use Simbrief, having already got the runway in use at the airport. I load that flightplan into the system, and press the ACTIVATE button, it all seems to work. 

However, even though I can't see anything I'm missing from the FMC, I can't light up the LNAV or VNAV buttons, as the training videos all seem to able to. My more urgent problem is actually getting the autopilot on. In the built - in 737, I can simply press the z-key, but it doesn't work for me until I'm in the air for some time, flying manually in the PMDG model. 

The LNAV button isn't as important as putting the 737 onto the standard autopilot, then engaging the auto heading for me. 

Does anyone know why the z-key can't work straight away, or the LNAV won't light up on the ground? 

Thanks, Gary


How does Moses make his coffee? Hebrews it.  

I took the shell off my racing snail, thinking it would make him run faster. If anything, that made him more sluggish.

Gaz on Facebook

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Gary,

I would suggest reading the introduction and tutorials much of the info is in there.

Introduction page 0.00.28

"I couldn’t get LNAV to arm/engage: LNAV has some specific parameters
that must be met in order for it to arm/engage. These are:
• To arm LNAV while on the ground: The first waypoint in your
flight plan must be within 5 degrees of the departure runway
course.
• To arm LNAV in flight : Requires a valid interception point for
active leg, interception angle less than 90 degrees OR within 3
miles cross tracks error OR within 3 miles from active. LNAV will
stay armed until interception."

Theres more to it... and a lot more to the plane when jumping from the default 737 into the NGX. The NGX requires an investment of time.. a significant investment of time and patience to learn how to fly it. But in the end, it is so rewarding because PMDG's NGX systems wise is (as far as what I hear) true to the real deal. Its a simulation, not a game.


Nick Dobda

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Gary,

the default autopilot function is actually not worth to remember 🙂 it will follow the GPS path set in the default GPS or in the flight planner, the only vertical modes are the VS mode. Forget about its function and engagement.

you need to comply with the requirements of the real autopilot, Nick has pointed them out. Additionally to arm anything on the ground your flight director(s) have to be activated. 

Your best bet is to check that the first waypoint matches the requirements and then you can arm LNAV. If not, for example if you depart without using a SID, you might want to dial in your runway heading at the HDG box and arm HDG SEL. 

VNAV shouldn‘t be an issue to be armed as long as your performance data was properly entered and executed. The tutorial is very detailed on this point. But VNAV normally goes with LNAV, if you chose HDG SEL for departure you likely would have selected FLCH as a vertical mode. (Note: not VS for climbing as it‘s not speed protected, it will hold the vertical speed, even though your engines might be too weak or loose power at altitude)

 

you can assign any key to the CMD button in the FMC options if I remember correctly.

Edited by Ephedrin

,

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When I started flying the NGX s a couple of years ago, I went through the Tutorials twice. 

Edited by Bobsk8

spacer.pngBob Cardone         MSFS 2020     PMDG DC6,  JF Arrow  , Carenado Seminole , Mooney,Simple Traffic  

TrackIR   Avliasoft EFB2    ATC  by PF3    FlyVirtual.net  CLX PC

 

 

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I appreciate your replies. 

Nick, I used simbrief to get my flightplan, leaving EGNT. When I used that, my first waypoint is not within 5 degrees, but leaving EGKK 8L, I belive it is. I will double check the latter plan, but as I said, I'm more interested in simply being able to engage the Heading mode and then follow the rules I'm given from ATC. 

BTW, I was using FlightSim in my teens for years, and I'm in my 40s now. I've only restarted because I'm now unable to work due to cancer and I wanted a hobby that I loved. My friends always tell me its a word not allowed game, and I correct them in saying what you said to me (about it being a simulator) , so I'm not that stupid. I may, however, be wrong about this forum being here for help. 

Ephedrin, thanks for that. As I said, and you picked up on, I am able to programme the FMC I believe, but I simply want to engage HDG SEL, as well as the other CMD buttons, such as to hold my vertical speed. However, I'm simply not able to get it to engage CMD after I have taken off. Sometimes I'm never able to engage it, despite my gear up and flaps up. 

Gary

 


How does Moses make his coffee? Hebrews it.  

I took the shell off my racing snail, thinking it would make him run faster. If anything, that made him more sluggish.

Gaz on Facebook

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. For the autopilot to engage, using LNAV and VNAV, you have to set up the FMC correctly. Often missed, when setting up the FMC, on the "INIT REF" page - after entering the ZFW, Reserves Cost Index, CRZ ALT, etc, - make sure you press the EXEC button. The words "PERF INIT" on the top of the page will change to "ACT PERF INIT".
. Enter "n1 LIMIT", and "TAKEOFF REF" info like flaps, CG and then enter your takeoff speeds (V1, V2 + V3).
. Enter your route, Origin, Dest, and waypoints. Then you have to remember to press "ACTIVATE" + "EXEC".
 Before takeoff, make sure you have entered your V2 speed and ATC approved flight level into the autopilot, both FD's are on, and Autothrottle is on.
. Set takeoff flaps, RTO set.
. When about +500ft/+700ft engage the LNAV/VNAV, then "A/P ENGAGE".


spacer.pngBob Cardone         MSFS 2020     PMDG DC6,  JF Arrow  , Carenado Seminole , Mooney,Simple Traffic  

TrackIR   Avliasoft EFB2    ATC  by PF3    FlyVirtual.net  CLX PC

 

 

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You also need to have the generators on line.  This one is often forgotten to those gaining familiarity.

 


Dan Downs KCRP

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Thanks Bobsk8, I'll make sure all that's done, but I think it was all like that already. 

Gary 


How does Moses make his coffee? Hebrews it.  

I took the shell off my racing snail, thinking it would make him run faster. If anything, that made him more sluggish.

Gaz on Facebook

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9 minutes ago, downscc said:

You also need to have the generators on line.  This one is often forgotten to those gaining familiarity.

 

Interesting. After the engines are started, I turn those on before the APU is turned off. Am I talking rubbish here when I'm thinking about generators? 


How does Moses make his coffee? Hebrews it.  

I took the shell off my racing snail, thinking it would make him run faster. If anything, that made him more sluggish.

Gaz on Facebook

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2 minutes ago, Gary McCluskey said:

Interesting. After the engines are started, I turn those on before the APU is turned off. Am I talking rubbish here when I'm thinking about generators? 

Nope, sounds like to got that part covered.


Dan Downs KCRP

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5 hours ago, Gary McCluskey said:

I appreciate your replies. 

Nick, I used simbrief to get my flightplan, leaving EGNT. When I used that, my first waypoint is not within 5 degrees, but leaving EGKK 8L, I belive it is. I will double check the latter plan, but as I said, I'm more interested in simply being able to engage the Heading mode and then follow the rules I'm given from ATC. 

BTW, I was using FlightSim in my teens for years, and I'm in my 40s now. I've only restarted because I'm now unable to work due to cancer and I wanted a hobby that I loved. My friends always tell me its a word not allowed game, and I correct them in saying what you said to me (about it being a simulator) , so I'm not that stupid. I may, however, be wrong about this forum being here for help. 

Ephedrin, thanks for that. As I said, and you picked up on, I am able to programme the FMC I believe, but I simply want to engage HDG SEL, as well as the other CMD buttons, such as to hold my vertical speed. However, I'm simply not able to get it to engage CMD after I have taken off. Sometimes I'm never able to engage it, despite my gear up and flaps up. 

Gary

 

Am I reading this right that you feel insulted by my first post?

The only thing I know about you is contained within those 5 lines you typed in your original entry. From those 5 lines I came to the conclusion that you were having trouble engaging VNAV & LNAV. I also deduced that you were new to the NGX but had some history with FSX using the default 737. If you had included more information (that you did include in your second post) I may have had a different response.  

I figured I would help you out and reply with some information/ advice that someone gave me in this very forum when I was new to the NGX.
Instead of typing "go read the manuals" I even went into the tutorial, cut and pasted the relevant info that I thought you would find helpful.

So I'm not sure how you came to the conclusion I thought you were stupid and that this forum is not here for help?

 


Nick Dobda

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18 minutes ago, Nick Dobda said:


So I'm not sure how you came to the conclusion I thought you were stupid and that this forum is not here for help?

 

 

First of all, it's not that I felt insulted, only frustrated.  This is software that I used some ago and don't seem to have remembered how to use it very well. My frustration is on  what I can't do, and why am I sometimes getting it to work, and sometimes not. I guess that's just something I put down to taking some more time training, which is the right thing to do. 

Now I feel that I have made you angry because of that reply - and honestly, I seriously apologise.

I think my frustration is just getting the CMD button to actually active, and also the HDG SEL, however, for my last couple of flights they seem to have worked finally. All of my passengers survived (believe it or not) until I got to Gatwick, and ATC told me to land on 8L using ILS 8R - or something to that effect.  I honestly lost the airport at that point. Any other landing has been fine (well, bumpy 😉 )

I'm sorry

Gary


How does Moses make his coffee? Hebrews it.  

I took the shell off my racing snail, thinking it would make him run faster. If anything, that made him more sluggish.

Gaz on Facebook

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Gary, no problem- its impossible to get tone from text so I was just concerned I ticked you off when I was just trying to help.

In any event, maybe this will help:

From the Introduction

Realistic Autopilot Engagement: This option can be used to simplify the autopilot engagement process if desired. When set to “Realistic Engagement” the autopilot will require that the airplane is in a balanced trim condition prior to accepting a pilot command to activate. Thus, if you are holding control input in place to maintain the desired flight path, you would need to re-trim the airplane until control force is no longer required to maintain the desired flight path. Selecting “OFF” will simplify the engagement logic for those who are just learning how to fly the simulator, thus reducing your workload. If you notice the autopilot failing to take control of the airplane when you press the CMD button, refer back
to this paragraph as a refresher!

Additionally, I don't think CMD A can be activated below 400 AGL. So if you just want to get it into HDG so you can steer like the old default 737, you gotta get it up over 400 and have the plane trimmed so that you are not putting pressure on your controls.

Either that or turn off the realistic autopilot engagement option - either will help you do what I think you are trying to

 

Hope this helps!

Edited by Nick Dobda

Nick Dobda

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2 minutes ago, Nick Dobda said:

Hope this helps!

It definitely does help - I really appreciate it!

Thanks

Gary


How does Moses make his coffee? Hebrews it.  

I took the shell off my racing snail, thinking it would make him run faster. If anything, that made him more sluggish.

Gaz on Facebook

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