diff --git a/ArduCopter/defines.h b/ArduCopter/defines.h
index efa8fe9f70..ff8f628bf9 100644
--- a/ArduCopter/defines.h
+++ b/ArduCopter/defines.h
@@ -106,6 +106,10 @@
 #define HIL_MODE_ATTITUDE			1
 #define HIL_MODE_SENSORS			2
 
+#define ASCENDING			1
+#define DESCENDING			-1
+#define REACHED_ALT			0
+
 // Auto Pilot modes
 // ----------------
 #define STABILIZE 0			// hold level position