Turbine D, from the linked (and well presented) Australian report:
Worldwide, errors associated with the use and management of automatic flight systems have been identified as causal factors in more than 20% of approach and landing accidents.
As our old NATOPS officer used to preach:
You have to know your systems inside and out.
This imperative is doubly true, IMO, when you are flying the trusting and paying public from one place to another.
One's ignorance can cost their lives as well as one's own.