Plane: suppress the throttle in auto-throttle modes after parachute release

ArduPlane/Attitude.cpp

@@ -558,6 +558,12 @@ void Plane::flap_slew_limit(int8_t &last_value, int8_t &new_value)
 */
 bool Plane::suppress_throttle(void)
 {
+    if (auto_throttle_mode && parachute.released()) {
+        // throttle always suppressed in auto-throttle modes after parachute release
+        throttle_suppressed = true;
+        return true;
+    }
+    
     if (!throttle_suppressed) {
         // we've previously met a condition for unsupressing the throttle
         return false;