... when the bad dream you had last night was about you remembering to lower landing gear when you're about to flare.
... when you can't find the mixture control when starting your car in the morning.
... when you're looking for the strobe and landing lights switch before leaving your driveway.
... when you catch yourself following the centreline in the road when "taxi'ing" to work.
... when you spend most of your lunchbreak reading about your favourite airplane on wikipedia.
... when ... ?