The mercator scale bar is a customized scale bar displayed on aeronautical charts using a mercator projection.
- Start ArcMap.
- On the main menu, click View > Layout View.
- On the main menu, click Customize > Toolbars > Aviation Layout.
- Click the Mercator Scale Bar button on the Aviation Layout toolbar.
By default, the mercator scale bar represents the current focus map scale if it is not zero.