Hello,

I would like to report an issue with the A220's LNAV lateral navigation.

The issue occurs while following the FMS flight plan during cruise. The aircraft repeatedly fails to properly track the programmed route, and the behavior continues through descent and approach until landing.

The issue I am experiencing is:

• Half Bank is OFF.

• When a relatively large turn is required, the aircraft does not increase the bank angle sufficiently.

• The bank angle appears to remain at approximately 10 degrees instead of increasing as required to follow the programmed flight path.

• As a result, the aircraft turns with a very large radius and cannot properly intercept the programmed track.

• The aircraft then overshoots the intended flight path during the turn.

• The XTK value on the navigation display (ND) increases, indicating that the aircraft is moving further away from the programmed FMS route rather than correcting back toward it.

• This behavior continues on subsequent FMS legs and persists through descent and approach until landing.

• Consequently, the aircraft is unable to properly capture and track the active FMS legs.

I suspect that this issue may be related to the Direct-To function, as I have noticed the problem after executing a Direct-To during cruise. However, this is only my assumption and I cannot confirm that the Direct-To function is the actual cause of the issue.

This does not appear to be simply a large turn radius caused by high altitude or high speed, as the bank angle itself appears to be limited to approximately 10 degrees even when a significantly larger bank angle would be required to follow the active leg.

Could you please confirm whether this is expected A220 LNAV behavior or a bug in the current Flight Guidance/LNAV implementation?

If I am doing something incorrectly when operating the FMS or LNAV, I would also appreciate it if you could let me know what I may be doing wrong.

Hi,

Thanks for your feedback.

Personally, I haven't encountered the issue you're describing. For troubleshooting purposes, are you currently using the default or Navigraph AIRAC data?

I'd also suggest joining the Synaptic Discord, where their team may be able to provide more direct troubleshooting support.

Thanks again!