iNavX offers for a while an "anchor alarm" feature, currently available at the bottom of the application Home page.
This function was frequently criticized as impractical.. iNavX 3.3.0 rectifies the failure in an improvement that makes it particularly clever now fully operational.
The "Anchor Alarm" function allows you to set the radius of a drift circle, with an adjustment from 0,01 NM (19 meters high) down to 0,30 NM (556 meters high) beyond which an alarm (Buzzer) Fires. Read more …