Plain English Meaning

The big outer ring of the two-part knob on the GPS or flight computer. You turn it to move from one box or letter to the next on the screen, like using a tab key.

Full Definition

The larger, outer ring of the concentric dual-rotation knob on a Flight Management System (FMS) or GPS control panel. Turning it moves the cursor between fields, pages, or characters on the display, allowing the pilot to select which item to edit. It works together with the inner knob, which changes the value within the selected field.

Context Anchor

Seen in GPS and glass-cockpit procedures, including instructions for using the nearest airport function.