When flying lower altitudes, you may see red or yellow hatched lines on the map that look like this:
This is called Terrain Awareness (TA) and is a graphical representation of aircraft height above surrounding terrain and obstacles, shown as colored overlays on the map. It is for general situational awareness purposes and is not intended to be the sole means of terrain or obstacle avoidance. Terrain awareness is often abbreviated as “TA”, but that is avoided in this document in order to prevent confusion with the same acronym being used for “Traffic Alert”. Terrain Awareness is based on GPS altitude, not baro corrected or radar altitude, and will not generate a CAS message or aural alert.
Terrain Awareness coloring can be triggered by terrain within a 10nm radius of the aircraft and is displayed as follows, depending upon the installation:
When the aircraft is more than 3000 feet above any surrounding terrain (1500 feet for helicopters), Terrain Awareness is turned off automatically. Terrain Awareness can also be triggered by obstacles as follows:
Terrain Awareness coloring is inhibited in an area immediately surrounding airports to allow for enhanced visual distinction of those facilities. If the orientation of runways at the airport can be determined, then the inhibited area will be based on the outlines of the runways. Otherwise, coloring will be inhibited in a circular area around the airport, including airports that have been designated as an airfield.
Terrain Awareness coloring can be turned off via the Setup Page (see Pilot Guide), but that setting will not affect Terrain Awareness for obstacles, which cannot be turned off.