only use the default acceptance radius for checking mission feasibility

src/modules/navigator/navigator_main.cpp

@@ -610,6 +610,12 @@ Navigator::publish_position_setpoint_triplet()
 	}
 }
 
+float
+Navigator::get_default_acceptance_radius()
+{
+	return _param_acceptance_radius.get();
+}
+
 float
 Navigator::get_acceptance_radius()
 {