During the flight phase CRZ and with VNAV, LNAV and AP activated, sometimes unexpectedly the 777, mainly in some change of course, loses the programmed route and I have to get it back manually.

Some idea?

 

 

Thanks in advance,

 

Francisco Mateos

Hi Francisco,

Could you post the route that you were flying and the point at which the aircraft deviated?

 

 

mainly in some change of course, loses the programmed route and I have to get it back manually.

 

This is very difficult for me to understand. What is "some change of course," do you mean you are changing a next waypoint that changes the course or do you mean when the aircraft is following a course that changes as you pass a waypoint???  Loss of programmed route, as in the FMS no longer has a route programmed??  So many questions. Please try to be more descriptive in your problem description.

It happens randomly​.

 

 

I want to say that when you pass a waypoint that changes the course of the route, not follow the one determined in the FMS, but follow one wrong. Normally a turn of 360°.

 

Only happens sometimes.

 

Excuse my English and thanks in advance. 

Hello Francisco,

Are you using time compression when this occurs?

Are you using the latest files? Download again from the PMDG shop if this is where you purchased the product, or check the vendor for the latest updated.

There was an update in January.

Sounds like you didn't program the FMC correctly. Can you post some screenshots and what you did in each step? That would be helpful.

I will install the last version and will test.

 

Francisco Mateos

Sounds to me like the aircraft missed a waypoint and then tried to turn back to it. If that happens use HDG SEL mode to steer back on the planned track then upload the correct next waypoint on the LEGS page and re-engage LNAV.