diff --git a/doc/Vario.txt b/doc/Vario.txt
new file mode 100644
index 0000000..e443822
--- /dev/null
+++ b/doc/Vario.txt
@@ -0,0 +1,42 @@
+== Vario Module ==
+
+- Pressing the "v" (down) button cycles between displays as follows:
+        
+    * vario (in m/s)
+	  Displays a signed fractional value representing the ascent or
+          descent speed in meters per second.
+
+    * vario (in Pascal)
+          Displays a signed integer value representing the ascent or
+          descent speed in Pascal/second.
+
+    * pressure (in hPa)
+          Displays a signed fraction representing the pressure measured at
+          the current altitude.
+
+    * max Vz (in m/s)
+          Displays the maximum vertical speed in meters/second.
+
+    * min Vz (in m/s)
+          Displays the minimum vertical speed in meters/second.
+    
+- A long press on the "#" button performs a context sensitive function:
+    
+    * during vario display, changes the vario sound mode:
+      Off      (default, no symbol displayed)
+      Ascent 0 (start beeping at 0.0m/s, beeper1 and beeper2 symbols
+               displayed)
+      Ascent 1 (start beeping at 0.1m/s, beeper1 symbol displayed)
+      Both     (beep for up or down, beeper1 and beeper2 symbols
+               displayed)
+
+      Tone frequency, number and duration of beeps depend on climb rate.
+
+    * during max/min Vz display, resets both the max and min values.
+    
+- The "record" icon is flashed at one second intervals, indicating that
+  the watch is in vario mode and receiving pressure measurements.
+          
+  Note that the upper line must be in altimeter mode for the vario to
+  work, as it relies on updates from the altimeter. If the altimeter
+  is not active, the vario display shows "noAlt".
diff --git a/include/project.h b/include/project.h
index 601cfd4..cb5fcfe 100644
--- a/include/project.h
+++ b/include/project.h
@@ -158,6 +158,8 @@ extern volatile s_message_flags message;
 // include firmware image
 #include "../config.h"
 
+// feature dependency calculations
+
 #if defined( CONFIG_PHASE_CLOCK ) || defined( CONFIG_ACCEL) || defined (CONFIG_USE_GPS)
 	#define FEATURE_PROVIDE_ACCEL
 #endif
@@ -166,6 +168,10 @@ extern volatile s_message_flags message;
   #define SIMPLICITI_TX_ONLY_REQ
 #endif
 
+#if defined (CONFIG_ALTITUDE) || defined (CONFIG_VARIO)
+  #define FEATURE_ALTITUDE
+#endif
+
 
 #if defined(CONFIG_INFOMEM) &&  !defined(CONFIG_SIDEREAL)
 	//undefine feature if it is not used by any option
diff --git a/logic/altitude.c b/logic/altitude.c
index df7e1ef..90f1867 100644
--- a/logic/altitude.c
+++ b/logic/altitude.c
@@ -42,7 +42,7 @@
 // system
 #include "project.h"
 
-#ifdef CONFIG_ALTITUDE
+#ifdef FEATURE_ALTITUDE
 
 // driver
 #include "altitude.h"
@@ -368,6 +368,7 @@ void mx_altitude(u8 line)
 //				u8 update		DISPLAY_LINE_UPDATE_FULL, DISPLAY_LINE_UPDATE_PARTIAL, DISPLAY_LINE_CLEAR
 // @return      none
 // *************************************************************************************************
+#ifdef CONFIG_ALTITUDE
 void display_altitude(u8 line, u8 update)
 {
 	u8 * str;
@@ -465,5 +466,6 @@ void display_altitude(u8 line, u8 update)
 		display_symbol(LCD_SYMB_ARROW_DOWN, SEG_OFF);
 	}
 }
-
 #endif // CONFIG_ALTITUDE
+
+#endif // FEATURE_ALTITUDE