diff --git a/libraries/AC_AttitudeControl/AC_PosControl.cpp b/libraries/AC_AttitudeControl/AC_PosControl.cpp
index 324479e0aa..c676bd0a48 100644
--- a/libraries/AC_AttitudeControl/AC_PosControl.cpp
+++ b/libraries/AC_AttitudeControl/AC_PosControl.cpp
@@ -932,6 +932,7 @@ float AC_PosControl::get_horizontal_error() const
 ///     should be called whenever the speed, acceleration or position kP is modified
 void AC_PosControl::calc_leash_length_xy()
 {
+    // todo: remove _flags.recalc_leash_xy or don't call this function after each variable change.
     if (_flags.recalc_leash_xy) {
         _leash = calc_leash_length(_speed_cms, _accel_cms, _p_pos_xy.kP());
         _flags.recalc_leash_xy = false;
diff --git a/libraries/AC_AttitudeControl/AC_PosControl.h b/libraries/AC_AttitudeControl/AC_PosControl.h
index d7439f2ac6..7e650dba58 100644
--- a/libraries/AC_AttitudeControl/AC_PosControl.h
+++ b/libraries/AC_AttitudeControl/AC_PosControl.h
@@ -187,6 +187,9 @@ public:
     ///     should be called whenever the speed, acceleration or position kP is modified
     void calc_leash_length_xy();
 
+    /// set the horizontal leash length
+    void set_leash_length_xy(float leash) { _leash = leash; _flags.recalc_leash_xy = false; }
+
     /// get_pos_target - get target as position vector (from home in cm)
     const Vector3f& get_pos_target() const { return _pos_target; }