diff --git a/ArduPlane/climb_rate.pde b/ArduPlane/climb_rate.pde
index 644be85a34..acf3762a7f 100644
--- a/ArduPlane/climb_rate.pde
+++ b/ArduPlane/climb_rate.pde
@@ -3,58 +3,58 @@
 #if 0 // currently unused
 
 struct DataPoint {
-	unsigned long	x;
-	long			y;
+    unsigned long x;
+    long y;
 };
 
-DataPoint		history[ALTITUDE_HISTORY_LENGTH]; // Collection of (x,y) points to regress a rate of change from
-unsigned char	hindex; // Index in history for the current data point
+DataPoint history[ALTITUDE_HISTORY_LENGTH];               // Collection of (x,y) points to regress a rate of change from
+unsigned char hindex;   // Index in history for the current data point
 
-unsigned long	xoffset;
-unsigned char	n;
+unsigned long xoffset;
+unsigned char n;
 
 // Intermediate variables for regression calculation
-long			xi;
-long			yi;
-long			xiyi;
-unsigned long	xi2;
+long xi;
+long yi;
+long xiyi;
+unsigned long xi2;
 
 void add_altitude_data(unsigned long xl, long y)
 {
-	//Reset the regression if our X variable overflowed
-	if (xl < xoffset)
-		n = 0;
+    //Reset the regression if our X variable overflowed
+    if (xl < xoffset)
+        n = 0;
 
-	//To allow calculation of sum(xi*yi), make sure X hasn't exceeded 2^32/2^15/length
-	if (xl - xoffset > 131072/ALTITUDE_HISTORY_LENGTH)
-		n = 0;
+    //To allow calculation of sum(xi*yi), make sure X hasn't exceeded 2^32/2^15/length
+    if (xl - xoffset > 131072/ALTITUDE_HISTORY_LENGTH)
+        n = 0;
 
-	if (n == ALTITUDE_HISTORY_LENGTH) {
-		xi -= history[hindex].x;
-		yi -= history[hindex].y;
-		xiyi -= (long)history[hindex].x * history[hindex].y;
-		xi2 -= history[hindex].x * history[hindex].x;
-	} else {
-		if (n == 0) {
-			xoffset = xl;
-			xi = 0;
-			yi = 0;
-			xiyi = 0;
-			xi2 = 0;
-		}
-		n++;
-	}
+    if (n == ALTITUDE_HISTORY_LENGTH) {
+        xi -= history[hindex].x;
+        yi -= history[hindex].y;
+        xiyi -= (long)history[hindex].x * history[hindex].y;
+        xi2 -= history[hindex].x * history[hindex].x;
+    } else {
+        if (n == 0) {
+            xoffset = xl;
+            xi = 0;
+            yi = 0;
+            xiyi = 0;
+            xi2 = 0;
+        }
+        n++;
+    }
 
-	history[hindex].x = xl - xoffset;
-	history[hindex].y = y;
+    history[hindex].x = xl - xoffset;
+    history[hindex].y = y;
 
-	xi += history[hindex].x;
-	yi += history[hindex].y;
-	xiyi += (long)history[hindex].x * history[hindex].y;
-	xi2 += history[hindex].x * history[hindex].x;
+    xi += history[hindex].x;
+    yi += history[hindex].y;
+    xiyi += (long)history[hindex].x * history[hindex].y;
+    xi2 += history[hindex].x * history[hindex].x;
 
-	if (++hindex >= ALTITUDE_HISTORY_LENGTH)
-		hindex = 0;
+    if (++hindex >= ALTITUDE_HISTORY_LENGTH)
+        hindex = 0;
 }
 #endif