Originally Posted by
Airmann
Thanks for this info, I've literally being flying for some years without any idea of what that symbol meant. But the question I have is does the FMS choose when to larch and when not to latch? Or is it the case that once the FMS is updated with the latch feature it will always be in latched mode during a managed descent.
Thanks
It latches once it gets to within some threshold from the profile. Exactly what the threshold is is unclear sometimes it won't latch until very close to profile and other times it will capture it from some vertical distance away. If you are 1000' above profile and in selected speed you can typically get it to NOT latch if you don't want it to. If you manage the speed then the FMGC will use the speed window to dive down and pick up the profile. In selected speed and unlatched the FMGC will respect the speed which may allow you to keep above the profile and stay unlatched (if that's what you want).