VNAV in FMC don´t work correct

Question

Hello Community,

I have trouble with VNAV using FMC with the B737-800. When I adjust speed and FL for each planned waypoint , the plane (B737-800 standard) will not follow VNAV. If I switch to V/S, then the buttons LCHG and N1 will be activated and the plane climbs to the altitude which is adjusted at the MCP (?) and not to the level of the FMC. Take care, if the altitude value of the MCP is lower than the FMS value, this is correct. If the value of the MCP is higher and ALT HOLD ist not activated, VNAV should be the master, but this fails during my tests.

If You reach the waypoint, where the descent has to start, You will see at least the same result, nothing will happen. Switching V/S on, the plane will descent and follows VNAV with various vertical sinkrates due to the descending angle.

May be ,You have to look, that VNAV, LNAV and LCHG ist activated at this moment. So finally You will reach the altitude level which You have adjusted at the MCP. It helps a little bit, to reach the initial point for the ILS, which You will expect for Your target airport

I have checked this several times, by using a short flight plan from EDDV/27L via NIE7F, NIE, IDEKO, ESTAD, OSTOR, OLDIP, CF32, FF32 to EDXW/32.

I ´ll thing, VNAV is a little bit buggy. Hoping of the experience of other flight simmers who can help me.

Cheers!

Horst

Comments

Hi Horst
Pleased to hear things are improving. I have an iPad on which I run WebFMC. A small file is added to X-plane plugins, which enables a browser to display and interface with the Zibo FMC. One port forwarding is required on your router, so simple setup.
The free version works well - https://greenarcstudios.com/

I have created a quick setup tutorial (in English) which you may find helpful.
https://youtu.be/dAVNY2ZfvBo

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Hi gkkes,

this is a good Information. At the moment I use my iPad as moving map. So this will be another way to use it.

I have two displays, so I can use "webfmc" at the second monitor. It's a good way to program the fmc and later observing it during the flight.

Cheers,

Horst

Answer 1

Hi Horst

I don't work for Laminar, but I fly the 737 exclusively.

You may have heard of the Zibo Mod? This is a free modification using the Laminar base and expanding it's capabilities.
Like much of X-plane, the community is given the development tools, and are encouraged to improve elements of the sim.
The Zibo is completely free like many other community utilities, aircraft and scenery.

I recommend you install this B737-800X which is a comprehensive improvement to the default 737.

It is a work in progress and gets intensive work and many updates. You can see some Youtube of this aircraft flown by a 737 Captain by searching youtube for flightdeck2sim

There is also The Zibo Community Facebook group

The software is here:

https://forums.x-plane.org/index.php?/forums/topic/138974-b737-800x-zibo-mod-info-installation-download-links/

Comments

Hallo gkkes,

thanks a lot for Your answer. I have the Zibo B737 installed too. After some trouble and informations  from a guy of the Aerosoft community, I find the missing Perf Parameters and so today I was able to fly also with VNAV PATH.

What I am missing, is, that it is not possible to open the FMS in a separate window. Programming is possible by zooming. But during the flight it´s hard to look at it. But it works.

The other point is, You can store a plan, but until now I do not find a way to call it up again. Sorry FMS is really new for me, I am not well experienced at this moment. I should look for a CPL training course .

The FMS installed in the standard B737 gives a lot of challenge for me. If You press VNAV, N1 and LVL CHG will be automaticly activated. You will see that VNAV PATH is "on" and the plane climbs to the adjusted VNAV altitude. So far so good. To descend at the initial point, I switch back to V/S and activate than VNAV again. The Question is, is it a bug or a fault by me.

Nevertheless, I think I use for the next future the Zibo, as You required.

Cheers!

Horst

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Hello Gkkes,

today I find out all missing entries of the FMS. So I  start again the flight between EDDV / EDXW.

All was working well with the Zibo B737, finally I reached EDXW under good condition, with full succcess. Thanks again for Your assistance.

Cheers,

Horst!

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Now I find a way loading the flightplan, Zibo described it in another forum.

Firstly You have to fill out DEP Airport, than ARR airport.

Secondly You write the file name without extension into the scratchpad an press the button COROUTE.

Now the flightplan data are loaded to the FMS.