<short_desc>Vertical position error threshold</short_desc>
<long_desc>This is the vertical position error (EPV) threshold that will trigger a failsafe. The default is appropriate for a multicopter. Can be increased for a fixed-wing. If the previous position error was below this threshold, there is an additional factor of 2.5 applied (threshold for invalidation 2.5 times the one for validation).</long_desc>
<long_desc>Specify the threshold for triggering a warning for low local position accuracy. Additionally triggers a RTL if currently in Mission or Loiter mode. Local position has to be still declared valid, which is most of all depending on COM_POS_FS_EPH. Use this feature on systems with dead-reckoning capabilites (e.g. fixed-wing vehicles with airspeed sensor) to improve the user notification and failure mitigation when flying in GNSS-denied areas. Set to -1 to disable.</long_desc>