The representation of Minimum Safe Altitude (MSA) over an area, measured in feet above Mean Sea Level, look at 2<sup>2</sup>. This means that flying at or above 2200 ft all obstacles and peaks are safely avoidable even if pilot does not see them. Each chart section has its own MSA value.
<a href="//commons.wikimedia.org/wiki/User:Orion_8" title="User:Orion 8">Orion 8</a>
Derived from <a href="//commons.wikimedia.org/wiki/File:Baltimore-Washington_TAC_84.png" title="File:Baltimore-Washington TAC 84.png">File:Baltimore-Washington TAC 84.png</a>