diff --git a/sw/airborne/flightzone.c b/sw/airborne/flightzone.c
new file mode 100644
index 0000000000..657b2b95d1
--- /dev/null
+++ b/sw/airborne/flightzone.c
@@ -0,0 +1,129 @@
+/*
+ * $Id$
+ *  
+ * Copyright (C) 2007  Arnold Schroeter
+ *
+ * This file is part of paparazzi.
+ *
+ * paparazzi is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * paparazzi is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with paparazzi; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA. 
+ *
+ */
+
+/** \file  flightzone.c 
+ *  \brief check whether a point is inside the polygon limiting the 
+ *         competition area	
+ * 
+ * filename:        flightzone.c
+ * project:         MAV 2007
+ * description:     check whether a point is inside the polygon limiting
+ *                  the competition area
+ *                  
+ *                 
+ * todo:            - support concave/convex polygons
+ *                  - sort points automatically
+ *                  - minimize size of Orthogonal[]
+ *				   
+ * 				   
+ * limitations:     - boundary polygon has to be convex				   
+ *                  - points have to be ordered clockwise
+ *				   
+ * author:          Arnold Schroeter
+ * history:         
+ *                  2.9.07 initial version
+ *
+ */
+
+#include "flightzone.h"
+
+typedef struct { COORD_TYPE x;
+				 COORD_TYPE y;
+			   } POINT;
+
+POINT Corner[] = {
+				 12, 18,
+				 12, 25,
+				 15, 29,
+				 18, 25,
+				 18, 18, 
+ 				 13.5, 16,
+				 0 , 0}; // last corner is a dummy, which must not be deleted!!! 
+
+POINT Orthogonal[20]; // Attention!!! array must be at least as long as Corner[]
+
+unsigned char bNumberOfCorners = 0;
+
+/*******************************************************************
+; function name: vInitIsInsideBoundaries  	
+; description:   	
+;*******************************************************************/
+void vInitIsInsideBoundaries(void)
+{
+	unsigned char i;
+
+   	bNumberOfCorners = sizeof(Corner)/sizeof(POINT) - 1; // last corner is always a dummy
+
+	Corner[bNumberOfCorners].x = Corner[0].x;
+	Corner[bNumberOfCorners].y = Corner[0].y;
+
+	for (i = 0; i < bNumberOfCorners; i++)
+	{
+		Orthogonal[i].x =     Corner[i+1].y - Corner[i].y;
+		Orthogonal[i].y =  - (Corner[i+1].x - Corner[i].x);
+
+#if 0
+		printf("%d: corner (%f, %f), orthogonal (%f, %f)\n", 
+		        i, 
+		        Corner[i].x, Corner[i].y, 				    
+		        Orthogonal[i].x, Orthogonal[i].y);
+#endif
+	}
+
+}
+
+/*******************************************************************
+; function name: iIsInsideBoundaries  	
+; description:   	
+;                   
+; parameters: 		 
+; returns:       1 if point is inside boundaries
+;                0 if point is outside boundaries           
+;*******************************************************************/
+int iIsInsideBoundaries(COORD_TYPE x, COORD_TYPE y)
+{
+
+	int r = 1;
+	static unsigned char i; 
+
+ 	i = 0;
+
+   	while (    (i < bNumberOfCorners)
+	        && (r == 1)
+		  )
+    {
+		if (  (   (x - Corner[i].x) * Orthogonal[i].x 
+		        + (y - Corner[i].y) * Orthogonal[i].y
+		      ) < 0. )
+		{
+			r = 0;
+		}
+
+		++i;
+    }
+
+	return r;
+}
+
+