Lnav problem

I have this problem where when I turn lnav on it starts turning the wrong way and keeps that heading it’s very annoying since it ruins the whole flight. Any ideas or tips on how to fix?

P.S: what altitude should I turn appr on, I use it until I’m at about 1000 feet and then turn it off

Thank you!!

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Do you have your NAV mode set to GPS? It might be set to NAV1 or NAV2 after you used APPR for example.

The APPR usage seems fine to me :D


Thank you!! I will check it out! :)

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Hi there! This could be one of many problems involved in preparation for and proper activation of the APPR system. The system operations on contingencies that are dependent on the correct usage by the user (pilot). In this case, it could be one of many things, such as: 1) Did not tune into desired runway 2) Did not meet operating requirements (i.e. speed and altitude) prior to engaging the system 3) Could be related to weight and balance, or an issue with the interception of the localizer (if you engage it that late, since the system is capable of intercepting it as well).

Here is a tutorial which was produced by one of our Staff Members here in the community, Tyler. My DMs are open if you have any follow-up questions, or you have the option of asking said queries here.

Also, I would recommend changing this category to #support, since that is the appropriate categorization for this topic.


I believe OP is having a problem with LNAV rather than APPR mode.

I would also add make sure the correct leg of your flight plan is activated. When you don’t pass over a waypoint close enough, then the next leg won’t automatically activate so when you turn on LNAV the plane is essentially trying to fly back to the waypoint that you missed. To correct this, simply select the desired leg in the FPL and press activate leg.

Oops, good catch. Well, in that case, LNAV is a different system, with different operating requirements, and behaviors. I did though assume the OP was referring to the APPR (with the incorrect terminology) since this situation is awfully similar to situations with the misuse of the APPR. Good reminder though! :) This information is still relevant though in regard to a question asked, and in the general scheme of things in relation to transitioning from LNAV through NAV1 and eventually if the individual chooses, the APPR.

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Thank you very much!!

So you asked two questions:

  1. LNAV turning you away from the fix you expected;
  2. when to turn on APPR.

As for the LNAV turning away from the fix you had expected:

But this assumes this is true:

As for when to turn on APPR. @AviatorMan’s tutorial link is the gold standard for how to use APPR.
I’ll just point out two key pieces of info from that tutorial. Maximum angle (30 degrees) for intercepting the localizer (final approach coarse). But more importantly your question is about altitude to turn APPR on. 3000ft agl is given in the tutorial but with the conditions as described at 1min 4sec in the video.

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I’m not sure what its set at but I will check In the morning. Thank you!

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