TurnSafe 1.05

This program is designed to help glider pilots using only a GPS to decide when the FAI 90° quadrant (sector) at each turning point (TP) has been entered.

TaskNAV method
If you have access to TaskNAV, you can derive the safe bearings without using TurnSafe, as follows:

  1. Draw the task using Graphics Editor
  2. Select Print | Standard Task Report
  3. Note down (or print out) the bearings given in the Bis[ector] column
  4. For a clockwise task, subtract 40° from each bisector; for an anticlockwise one, add 40°
  5. Skip to step A.7 below
TurnSafe method
  1. Before flight
    1. Type in Start, Finish and TP names
    2. Type in bearing for each leg (preferably from GPS Routes page—or map)
    3. Leave unused TP lines blank—but fill in final leg bearing on Finish line
    4. Click on Calculate button
    5. Make a note of (or print out) the "safe bearing" for each TP
    6. For an out-and-return task 2 bearings are given: the first applies if you turn the TP clockwise, the second if you turn it anti-clockwise
    7. Make sure your GPS displays Bearing (to next waypoint) on the map page (you may have to use the Change Fields option on the menu)
    8. Activate the "route" (task) on your GPS

  2. In flight, approaching each TP
    1. Fly beyond and around the TP (ie to the left for a clockwise task; otherwise to the right).
    2. Monitor the TP bearing on your GPS (it will be increasing in a clockwise task; otherwise decreasing)
    3. As soon as you have passed through the "safe bearing", you can be sure that you are in the FAI quadrant (with a 5° safety margin). You can now fly straight towards the next TP.

       Name Bearing from previous TP Safe bearing for quadrant (calculated by program)


If you find this program useful, you are welcome to download this webpage for use offline. Simply click File | Save As ... to your hard disk.

Last revised June 2004
© N Greenwood 2004    Comments or suggestions