diff --git a/ArduPlane/ArduPlane.cpp b/ArduPlane/ArduPlane.cpp
index 353aa5fe33..1cf6bb3f04 100644
--- a/ArduPlane/ArduPlane.cpp
+++ b/ArduPlane/ArduPlane.cpp
@@ -797,6 +797,10 @@ void Plane::update_navigation()
     // ------------------------------------------------------------------------
 
     uint16_t radius = 0;
+    uint16_t qrtl_radius = abs(g.rtl_radius);
+    if (qrtl_radius == 0) {
+        qrtl_radius = abs(aparm.loiter_radius);
+    }
     
     switch(control_mode) {
     case AUTO:
@@ -809,7 +813,7 @@ void Plane::update_navigation()
         if (quadplane.available() && quadplane.rtl_mode == 1 &&
             (nav_controller->reached_loiter_target() ||
              location_passed_point(current_loc, prev_WP_loc, next_WP_loc) ||
-             auto_state.wp_distance < (uint16_t)g.rtl_radius) &&
+             auto_state.wp_distance < qrtl_radius) &&
             AP_HAL::millis() - last_mode_change_ms > 1000) {
             set_mode(QRTL, MODE_REASON_UNKNOWN);
             break;
diff --git a/ArduPlane/quadplane.cpp b/ArduPlane/quadplane.cpp
index 914f0717d3..a7d90a6fb7 100644
--- a/ArduPlane/quadplane.cpp
+++ b/ArduPlane/quadplane.cpp
@@ -259,7 +259,7 @@ const AP_Param::GroupInfo QuadPlane::var_info[] = {
 
     // @Param: RTL_MODE
     // @DisplayName: VTOL RTL mode
-    // @Description: If this is set to 1 then an RTL will change to QRTL when the loiter target is reached
+    // @Description: If this is set to 1 then an RTL will change to QRTL when within RTL_RADIUS meters of the RTL destination
     // @Values: 0:Disabled,1:Enabled
     // @User: Standard
     AP_GROUPINFO("RTL_MODE", 36, QuadPlane, rtl_mode, 0),