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This page contains special information for scorekeepers, competition pilots.

For Competition Pilots and Scorekeepers

Altitude Discrepancies in Competition Scoring

In an attempt to keep competitors out of airspace, competitions have been imposing penalties for violating airspace ceilings.  There is, however, an inherent problem when evaluating a pilots altitude from the track log used for scoring.  While the 6030, 6020, 5030, 5020 (and comparable Brauniger models) record both GPS and pressure altitude some of the common scoring programs only plot GPS altitude.  Due to the inherent errors in the way pressure and GPS altitude is calculated, it is seldom that the altitude reported using these two systems agree and it is quite common that GPS altitude will report altitude higher than pressure altitude.  Since all flight instrument's use pressure altitude to display MSL altitude, it is possible for a pilot to stay below an altitude ceiling only to have their track log (when viewed in a scoring program) show them above the ceiling. 

The problem is exacerbated by the misconception that 3D GPS  (e.g., 76S, 76CSX, Etrex Vista, Geko 301, etc.) commonly used in competition, provide GPS altitude in their track log.  In reality all these devices have pressure sensors which are used to measured short term altitude changes (consistent with a competition task). To prove this, a Garmin 76CS and Etrex Vista was put into a pressure chamber (visible to the sky) and driven down a level road.  The pressure in the chamber was slowly reduced and then increased. The track log (.igc file) viewed in Google Earth shows the car taking off, flying and then landing! You can see the track log here. This means that scoring software could unfairly show a pilot, using a flight instrument, to have violated a ceiling, while showing a pilot, that flew the exact same path using a 3D GPS, under the ceiling.

Recommendation

In cases where scoring software shows a pilot violating a ceiling by a relatively small amount (200m) the scorekeeper should examine the flight instrument pressure altitude to determine if the pilot actually violated the ceiling.

Turnpoint Discrepancies in Competition Scoring

The various scoring programs used in hang gliding/paragliding competition calculate distances between two points on the Earth’s surface using two different earth models: the FAI sphere or the WGS84 ellipsoid. Flytec instruments calculate distances using the FAI sphere, whereas some scoring programs like Compe GPS Competition use the WGS84 ellipsoid. Distances calculated between two points can disagree between these two models.  Consequently, scoring programs that do not use the FAI sphere model may not exactly agree with the flight recorded by the instrument. This is of particular importance when determining if a pilot has crossed a start or turnpoint cylinder.  For this reason the PWC recommends a tolerance of 0.5% on distance measurements to allow for the different earth models and calculation and rounding error.  Full discussion of this issue here.

If this situation arises in a competition, where the pilot is certain that he had heard the “turnpoint reached” alert as he crossed the cylinder, and the scorekeeper does not grant this waypoint because the scoring program shows the pilot short of the cylinder by only a few meters, we recommend the pilot file a protest and that the distance is recalculated with this calculator: http://williams.best.vwh.net/gccalc.htm

For Scorekeepers

The new Flytec 6030/6020 and Bräuniger Compeo+/Competino+ are not a true USB device. It simply has a USB to serial converter built directly into the instrument. From a software standpoint it is still a serial device with the same protocol as the 5030.  Consequently almost every flight analysis program can handle the Flytec 6030, 6020, Compeo+ and Competino+  All that is needed is that converter driver be installed on your computer. Drivers for your operating system (Windows, Mac or Linux) can be downloaded from here: USB-Driver.

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