Loss of Navtrack when setting the descent winds

[Bentree_ 9]

Hi guy's,

I have something strange going on.

Since this week i do a proper descent planning by settings the altitude winds in the DES page of the FMC.

Every single time when i do this (the aircraft is still in the VNAV Climb on NAV) the aircraft start turning to the left 90 degrees and diverts from the track.

the VNAV track is set with now disco's, still have to set the descent track though.

Does anybody have had this same problem?

Regards,

Ben

[Bentree_ 9]

I found out what the problem is.

When you fill in the wind direction and speed at altitudes for descent in the DES page, the FMC route has to be activated again.

I am familiar with boing FMC's but not with this behaviour of the FMC.

Is this normal for the MD80 FMC?

Regards,

Ben

[J. Eberhardt 3]

I know that, in this case quickly i press the nav Button,  then it returns, but maybe there is another way to prevent this?

[Bentree_ 9]

But it is not that the NAV disconnects.....the route is deactivated while setting up the altitudes and winds for the descent.

Regards,

Ben

[kristolz 26]

I’ve seen something similar a few times, when altering altitude constriaints on a STAR during descent, that the AP will start a left turn for no reason, and continue to do so, probably to catch a waypoint not visible on the ND, nor the McDU. The FD mode is still showing NAVTrk, although the plane is flying all by itself further and further away from the magenta line. Seems like a bug to me. Does not happen every flight, so not entirely sure how to reproduce it.. 

[JRBarrett 3,071]

I had a similar problem - P3D4.2 with the latest MD release. As soon as I started making entries on the descent forecast page, the aircraft started turning off of the present track.

[Bentree_ 9]

At this moment i fly LGKR - LGSM and checked what exactly is happening.....

In the Climb (FMA setting: FMS EPR - 330 - NAV TRK - VNAV CLB) i set in the DES FORECAST page the descent altitudes and wind speeds, the moment i start with the first input the Pink NAV line turns to a blue spotted line but the aircraft stay's on track but........

The moment i EXEC the altitude and wind settings (i have set 5 of them) the aircraft starts a left turn and deviates 90 degree from the FMS Track. On my system it happens 10 out of 10 times.

I submitted a ticket for this....this must be a bug.

Regards,

Ben

[J. Eberhardt 3]

Hi Ben, have you already got a reply ?

Your last post is just the same as it is with me - as I said, after i pressed die Exec Button i quickly press the nav button, then it works again.

[Senchai 24]

I reported this already a few weeks  ago. Same happens to me.

Edited April 3, 2018 by SaenchaySor

[Dreamflight767 312]

Happening to me too!

[Bentree_ 9]

Hi Guy's,

the problem is adressed in the 1.10 update that is out.

Regards,

Ben