http://ozreport.com/13.044#1

Steve Kroop <<email>> writes:

If the organizer at the worlds (or any organizer for that matter) assigns a zero score for violating airspace they are making a mistake. A zero is an absolute penalty, yet we have no way to measure altitude absolutely.

Absolute penalties should be reserved for infractions that can be determined with certainty. Currently competitions are relying on GPS altitude for determining violations. I have written extensively about the problems with GPS altitude and the summary is that the GPS altitude reported (and recorded) by an individual GPS unit is affected by geometry of the acquired satellites in relation to the GPS receiver at that time and location, the quality of reception, the quality for the GPS unit and the type of filtering used by the GPS, to name a few.

In other words, one GPS may show a given point to be be above ceiling while another GPS may show the same point below at the same moment in time. Additionally, the same exact GPS may show that point above the ceiling at one point during the day and below at another.

I think it is a good objective to keep competitors out of clouds and airspace, but it should not be done capriciously. A penalty amount that would remove any possible benefit from violating the ceiling would seem more appropriate. Perhaps a zero can be reserved for gross airspace violations where it is obvious that the pilot broke the ceiling willfully and not a result of the technical limitations of our equipment.

The articles and discussion (1, 2) on altitude measurements (individually: 12.122#0, 12.126#1, 12.194#2, 12.196#0, 12.197#0, 13345, 12.207#0, 13.012, 14559, 13.013#2, 13.015#2, 13.016#4, 13.017#4).