PMDG 737-600 LNAV wont engage?

User Support Hub Aircraft & Systems
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1

My flightplan is loaded correctly via FMC and even the display shows the right next wpt (EXITI in this case) but when i try to engage LNAV nothing happened no matter how often i push the button. Compared to LFVR Airbus A320 the PMDG Boeing 737 is a big miracle. How can i engage LNAV? In some flights it worked out but sometimes not. Since i followed always the same procedure i am clueless.

2

You have to be on an intercept course to the leg your flying for it to engage

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3

Did you activate the Flightplan? Whenever I flown the PMDG, I was able to use VNAV/LNAV, but at the beginning I forgot to activate everything which gave me the same problem. That’s a small difference to the Airbus.

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4

I did. There is a great vid on yt.

5

It always wanted me to fly to a nav somewhere east of Hamburg allthough i was already nearby Hannover. So that was i between?

6

Well, I don’t use the Simbrief import, I type it manually. Anyway, if everything is correct loaded and activated, it must work.

7

Now after trying a lot of things in FMC i could activate LNAV but tbh i dont know exactly why? I followed this vid at yt which is quite good i think.

8

No screenshot available? It makes it easier to see the problem.

9

Yes i did that too in the past but planning with Simbrief is more convenient.

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10

Are you engaging LNAV on the runway prior to takeoff roll? If so, IIRC if the first waypoint is more than ~15 degrees* off of runway heading, LNAV won’t engage. Either hand fly it or put in HDG mode to get tracking towards the first waypoint, then LNAV should be available. This is real-world behavior from what I understand.

*CORRECTION: +/- 3 degrees, per @Downscc below.

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11

Hi, as in your’e other post, did you put the SID in the FMC dep/arr page

12

The actual allowable variance is +/- 3 deg of extended runway centerline for LNAV engagement on the ground. If the variance is greater then use HDG mode. There are times where one gets to fly instead of following the magenta line.

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13

This happened to me until I realised I had not turned both FD’s on?

14

Yes i did.