diff --git a/APMrover2/mode.h b/APMrover2/mode.h
index 7312935fc7..a016f19c15 100644
--- a/APMrover2/mode.h
+++ b/APMrover2/mode.h
@@ -39,11 +39,11 @@ public:
     // attributes of the mode
     //
 
-    // return if in non-manual mode : AUTO, GUIDED, RTL
+    // return if in non-manual mode : Auto, Guided, RTL, SmartRTL
     virtual bool is_autopilot_mode() const { return false; }
 
-    // returns true if the throttle is controlled automatically
-    virtual bool auto_throttle() { return is_autopilot_mode(); }
+    // returns true if vehicle can be armed or disarmed from the transmitter in this mode
+    virtual bool allows_arming_from_transmitter() { return !is_autopilot_mode(); }
 
     //
     // attributes for mavlink system status reporting
diff --git a/APMrover2/radio.cpp b/APMrover2/radio.cpp
index 6565e47c7b..837b693c1c 100644
--- a/APMrover2/radio.cpp
+++ b/APMrover2/radio.cpp
@@ -52,8 +52,8 @@ void Rover::rudder_arm_disarm_check()
         return;
     }
 
-    // if not in a manual throttle mode then disallow rudder arming/disarming
-    if (control_mode->auto_throttle()) {
+    // check if arming/disarming allowed from this mode
+    if (!control_mode->allows_arming_from_transmitter()) {
         rudder_arm_timer = 0;
         return;
     }