The LNAV of A350 V1.1.8 goes crazy when turning between adjacent waypoints

[Tim Cui]

Hello everyone! For two consecutive days, I have encountered a situation where the aircraft's LNAV malfunctions and keeps circling repeatedly between the ORAVA and UNSEK waypoints (as shown in the figure). Other pilots have also informed me that they have encountered the same issue. Could the cause of this problem be incorrect LNAV coding or something else? Everything in the aircraft cockpit is normal with no alarms whatsoever— the only issue is that the LNAV is not following the planned route.

[Transair]

I also had this wavy approach on a STAR into EDDF.  Aircraft could not perform the Star at all..  What causes this?

[iniSteven]

I take it you didn't read all your NOTAM's before you flew 😉

 

These waypoints are an issue IRL as well. The correct procedure is to plan direct from MUDOT to UNSEK when flying eastbound.

 

[Tim Cui]

11 hours ago, iniSteven said:

I take it you didn't read all your NOTAM's before you flew 😉

 

These waypoints are an issue IRL as well. The correct procedure is to plan direct from MUDOT to UNSEK when flying eastbound.

 

I asked my friends today and also checked the NOTAMs — in reality, the route is indeed flown directly without passing those waypoints. However, shouldn’t the LNAV’s improper handling of two consecutive turns be something that the development team should pay attention to? I’ve flown the same route with other aircraft before: although they deviated a little, they were still able to correct themselves and return to the proper path. But the A350 kept circling continuously. I believe this is an issue with the coding.

[Tim Cui]

11 hours ago, iniSteven said:

I take it you didn't read all your NOTAM's before you flew 😉

 

These waypoints are an issue IRL as well. The correct procedure is to plan direct from MUDOT to UNSEK when flying eastbound.

 

But this can be treated as a low-priority fix, since I’m not familiar with how the A350 behaves in real life either. Thank you for your reply.