Plain English Meaning
This is the point in training where the learner stops practicing a skill and simply uses it to fly. The skill has been learned well enough that it can now be applied to do real work in the cockpit.
Full Definition
The third and final stage of skill acquisition in aviation training, in which the learner performs a previously practiced skill in a real operational setting and uses it to accomplish an actual flight task, rather than performing it as a rehearsal or training exercise. At this stage the learner is no longer thinking through each step; the skill has become reliable enough to be used as a tool for getting something done.
Context Anchor
Seen in aviation instruction when an instructor is judging whether a student can use a learned maneuver, procedure, or decision-making ability in real flight situations.