Definition
On the attitude indicator, a pitch reference equal to half the thickness of the miniature aircraft's wing bar, used to set or describe small, precise pitch attitudes relative to the artificial horizon.
Plain English
It means moving the little airplane on your attitude indicator up or down by half the width of its own wing, as a small, measured pitch change.
Context Anchor
Seen when learning to hold straight-and-level flight using the attitude indicator.
Why Pilots Care
Prevents over-correction and altitude excursions by giving pilots a consistent, small reference for attitude changes.
Analogy
Think of the wing bar on the attitude indicator as a small ruler built into the instrument. A 'one-half bar width' change is like nudging something half a ruler-mark up or down.
Grounding Statement
On the attitude indicator, one-half bar width is a tiny visual correction, not a dramatic control movement.
Intuition Check
Do not read “one-half bar width” as a fixed distance or a fixed number of degrees. Here it means half of the visible reference bar on that specific attitude indicator display.
Example Sentence 1
To start a gentle descent at cruise speed, the pilot lowered the miniature aircraft one-half bar width below the horizon line.
Example Sentence 2
During level flight, any altitude drift was corrected with no more than one-half bar width of pitch adjustment.