http://ozreport.com/13.006#2

I flew with a Flytec 6030 and Gerolf flew with a Gecko 301.

Bruce Kavanagh <<email>> writes;

As you are aware I've been try get to the bottom the issues with altitude verification so that we can persuade CIVL to adopt a more satisfactory solution to this problem. The Garmin units with pressure transducers do not record GPS altitude but instead record GPS altitude which can be adjusted to whatever setting the user wants either before or during the flight.

The Gecko 301 has a pressure sensor so I believe it records pressure altitude whereas the 201 does not have a pressure sensor so records GPS altitude.

As you mention auto-calibrate was on that implies that Gerolf was flying with the 301.

I'm not sure what the auto calibrate option does and the manual does not explain. It is likely that it sets the altimeter to the GPS altitude when you switch it on and then relies on the pressure sensor from there on. In which case I would expect the Gecko to be reading a lower altitude than the GPS altitude from your 6030 once you both got high. On a hot day 560ft difference is about what you'd expect at around 6-9000ft above launch depending upon how hot it was.

It was 43 degrees Celsius (109 Fahrenheit) that day in the tow paddock.