Avidyne IFD540 Pilot's Manual page 108

NOTE
Heading vs. Track Depictions
In configurations in which aircraft heading
information is unavailable, the map display will
orient the aircraft ownship symbol and other map
data to the aircraft ground track and continue to
display intruder aircraft oriented to heading.
TIPS AND TECHNIQUES
Heading/Track Digital Display Can Be Removed
A map setup choice provides a means to remove
the heading/track digital readout box from the top of
the map. This is intended to provide a method to
increase usable map space, especially on dual IFD
installations where cleaner maps are desired.
NOTE
Map Orientation Without GPS
The map orientation will auto-switch from track-up
orientation to north-up orientation when GPS is lost.
Pilots who leave the map orientation in track-up
during shutdown may notice the map will start up in
north-up until a GPS position fix is available, at
which time the map will auto-switch to track-up.
NOTE
Terrain Resolution
The map uses 9 arc-sec terrain data globally. There
are however, some locations where the terrain
database fills in missing terrain cell data and the
map terrain will visually appear to be a lower
resolution background in those locales.
3-4 Map Pages