II Morrow Inc. 920 - Manual (Page 52)

If you choose airspace alerts, you can select:
n
whether or not alert messages are issued
n
the type of message - Class B and C,
Special Use (Restricted, Danger), or All
n the radius distance from the airspace
border at which to be alerted
n
the travel time (based upon current track
and speed) from the airspace border at
which to be alerted
Special Note: The type of message selected
here also controls the type of airspaces
displayed on the map screens and on the
message page.
If the receiver is computing a 3D position fix,
the GPS altitude will be used to avoid an alert
message when above or below the airspace
ceiling or floor. To compensate for the
inaccuracies of GPS altitude, a buffer of 1,000
feet is added to the ceiling and subtracted from
the floor. For example, if the published ceiling
Change
Settings
D
11