Chronic Unease
A beginner is clueless. An intermediate knows they know enough (sometimes a synonym for "everything"). An expert understands the limits of their knowledge and awareness and therefore maintains a state of chronic unease.
This is a frame of mind that takes little for granted (did we succeed because we were lucky?) and maintains a heightened awareness of the situation looking for signs of deviance (why are things not going according to plan?).
You have this driving down the road. Your eyes scan the road (unless you are texting) looking for the car at the intersection, the slippery surface and even the speed limit change. The small adjustments of the steering wheel to keep the car on the road are reactions to deviance (fail to adjust and you end up in the ditch).
Chronic unease takes training to learn and energy to do. Crew members help each other to achieve this.
In Search of the Perfect Crew