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00Aidan

VNav not working

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I know this is a dumb question but I'm new to the 737 NGX and I'm in able to use the VNAV. I've tryed every thing and I can only get the LNAV working.

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I know this is a dumb question but I'm new to the 737 NGX and I'm in able to use the VNAV. I've tryed every thing and I can only get the LNAV working.

 

Have you flown the tutorials?

 

Full names in the forum please - first and last.

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Yes many times and I can't seem to figure it out even with things like FS2crew

 

And VNAV isn't working in the tutorials?

 

Again - full names, please. Simply ensure that you're typing your name in your posts.

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No for some reason it does not activate because whenever I try to turn on vnav it just turns itself off

 

And my full name is Aidan Allen

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No for some reason it does not activate because whenever I try to turn on vnav it just turns itself off

 

What does the flight mode annunciator (FMA) say at the top of the primary flight display (PFD)? Make sure you follow (and read) the tutorial very carefully.

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I do not have access to my computer right now because it is currently being repaired but I will try it again on Wednesday and I will fill you in on that.

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I try to turn on vnav it just turns itself off


Aiden, 

 

This software addon is an extremely large jump from the default 737, and the learning curve is steep. It is very critical to read and digest the tutorials. Even when you've mastered them, there will still be many many questions that take time to learn. Thats half the fun, though - very satisfying when you get to the point of understanding everything. 

But if you've flown the tutorials and don't know why the VNAV (or probably the autopilot itself) disconnects when you turn the wheel, then you haven't read carefully enough. 

Even still though, I've been at it a year and a half and learn every time I boot up the game.

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I'm going to be honest about this I have never flown a Boeing aircraft let alone the default ones I skip those cause I heard they were junk I jumped to this one from aerosoft Airbus A320 and I'll tell you it's much easier to fly this is much more of a challenge and i'm having alot fun unraveling all the secrets of this aircraft. But that darn VNAV is a pain!!!

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But that darn VNAV is a pain


Is your plan to "hand fly" the 737? Thats perfectly fine, but if thats the case, then why do you want VNAV to work? If you don't want to get into the complexities of what VNAV is doing and why, you could just avoid it alltogether and use some other automation like V/S, or LVL CHG... the V/S works just like it did in the default Airbus I think. Alot of the fun for me is learning what the plane is dong and why... like why am I using VNAV in the first place?

Another thing thats different between the NGX and the default aircraft is the fact that if you put pressure on the controls, the AP turns off. There are some things you can do to have partial automation. That might be your problem. 

 

But the original point is this is all explained in the tutorial, which is really really critical to read and comprehend in order to understand what things like VNAV are doing and how they work. 

The folks who put the plane together really did a good job with those tutorials in getting the fundamentals of flying the plane down. Problem is you really have to read and comprehend what they are saying. You really can't just jump in and fly it... its just too complex. 

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I do use the autopilot a lot and both of these aircraft when I say it's fun to fly I mean that it's fun to use the system was professionally and I find that the Boeing 737 is much more complex that's why am having issues with the VNAV only been using the altitude hold because I fly on pilotedge a lot vnav I would be a lot more helpful but I will give the manuals and tutorials another run through

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Aidan, make sure that you have completed the PERF INI page in the CDU. The FMC needs to know the whole flight profile otherwise VNAV will be inhibited. Make sure your autothrottle is turned on. Make sure that you are above 400 feet radio altitude. And make sure you are not switching it off by selecting another pitch mode in the MCP.

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Remember folks, VNAV has ZERO do do with autopilot operation. Hand-flying can be in any mode (excepting auto-land, of course).

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I embarrassed myself only yesterday when I was showing a friend a take off using PMDG 737 and I also could not engage VNAV.

I discovered that I had not activated the flight plan and then pressed the EXEC button on the FMS. Silly me!

When you activate it you should still have a blue dotted line showing proposed flight path on the navigation display and when you press the EXEC button on the FMC you will have a solid pink line.

Then the jolly ole VNAV worked!!

Hope this will solve your problem?

 

Kind regards

Richard

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In that case, LNAV would not work either. That is why I suggested the PERF INI page. The OP has not come back yet.

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In the off chance other people reading this, for me it is always the PERF page that i keep forgetting activating :) After that usually VNav starts to work.

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Hallo,

I had the same prblem.
The reason was:

I forgot an entry in the field "FLAPS"
IN FMC - capitel "TAKEOFF".

All necessary data must be entered

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I also noticed that VNAV does not engage if you do not stay close to the "V2+20 knots" climb speed immediately after take off. This happened to me many times in the 737 NGX until I accidentally discovered the source of the problem! Having said that, I can quite happily fly the aircraft using LVL CHG instead.

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Just now, Christopher Low said:

I also noticed that VNAV does not engage if you do not stay close to the "V2+20 knots" climb speed immediately after take off. This happened to me many times in the 737 NGX until I accidentally discovered the source of the problem! Having said that, I can quite happily fly the aircraft using LVL CHG instead.

I think the actual issue is more that you need to be in trim, and you're likely out of trim if you're off speed.

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One thing I can tell you is it is very important you program the FMC in a particular order

If you look at the first tutorial it will list the order that you need to input information into the FMC

The other major thing is do you have both Flight directors turned on? if you are using the 2d panels you will not see the copilot Flight director you have to get used to using the 3d panels

 

 

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7 hours ago, Christopher Low said:

I also noticed that VNAV does not engage if you do not stay close to the "V2+20 knots" climb speed immediately after take off. This happened to me many times in the 737 NGX until I accidentally discovered the source of the problem! Having said that, I can quite happily fly the aircraft using LVL CHG instead.

That sounds odd to me. What modes are you seeing then? Are you entering LVL CHG by selection? Are you arming VNAV before T/O?

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I always arm VNAV and LNAV before take off, but VNAV seems to "switch off" when I am above 400 feet if the climb speed is not reasonably close to "V2+20". When this happens, I see ALT HLD on the FMA when I reach cruise altitude (which in my case is only 5000 feet at the moment; I will need to check what is displayed when I am climbing). I can reactivate VNAV if I want to, but sometimes it is just easier to use LVL CHG on descent. I am not bothered about following real world restrictions to the letter, so I tend to give myself plenty of time to reduce speed/altitude when approaching my destination.

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