How Track Validity Checks Work
Checking that a tracklog is really your flight of this task
Why Tracks Get Checked
A pilot sometimes uploads the wrong file: a flight from another day, or from another site. The mistake is easy to make and difficult to see. The file is valid IGC, it opens, and it looks like a flight.
The scoring cannot find this mistake. Tasks often run across UTC midnight. GlideComp therefore resolves the start gates and the deadlines against the flight it scores, and not against a fixed date. A tracklog from another day therefore moves the whole task onto its own day, and scores as if nothing is wrong.
FAI S7A §4.4.2 makes this the work of the software. The points that verify a flight must have "occurred at reasonable times (e.g. on the day in question)".
The Two Checks That Withhold a Track
Both checks ask one question: is this file this flight? Both use margins that no honest entry can reach.
Wrong day
GlideComp compares the fixes against the calendar day of the task, in the time zone of the competition, with four more hours at each end. The check fails only when every fix is outside that window. An overnight recorder, a dawn launch and a flight across local midnight therefore all pass. An error of up to one day is flagged, not withheld. A recorder set one day wrong is a common fault on a real flight.
Wrong location
No fix comes within 100 km of a turnpoint. A long course does not make this check more strict, because the turnpoints are spread along the course. Every pilot who launched starts metres from one of them.
A track that fails either check stays out of the scoring and out of the field analysis. In the field analysis, its clock and its air distort the day's statistics for all of the other pilots.
The Three Flags That Never Change a Score
These three flags describe the flying, not the file. Each one also fires on real flights, so GlideComp shows them for a person to judge. They never change a score.
- Never left the take-off cylinder. This is what a pilot looks like who launches and sinks straight back to the ground, and GlideComp correctly scores them the minimum distance. It is also what a recorder looks like that the pilot left running on launch.
- No sign of flight. There is no sustained climb (1.5 m/s for two minutes) and no sustained glide (90 seconds of descent at 0.8 m/s, never below 4 m/s over the ground, and approximately straight). This flag catches a vario that recorded the drive up to launch. Speed alone cannot catch it, because a retrieve vehicle is faster than a paraglider.
- Impossible speed. The ground speed stays for a full minute above approximately 119 km/h for paragliders, or 162 km/h for hang gliders, with the tailwind included. The one-minute window keeps GPS jitter out. This flag looks for something that is not a glider.
What It Does to the Score
GlideComp scores a pilot who launches and lands short the minimum distance, approximately 5 km. That does not change. A short flight with bad luck still gets it.
A withheld tracklog is different, because it is not evidence that the pilot flew this task. Those pilots keep their place in the results with zero points, and the reasons stay beside their name. GlideComp never removes them from the standings.
No other pilot's score moves. GlideComp leaves the pilot out of the launch-validity count ( S7F §9.1 ), instead of counting them as a pilot who flew. A wrong verdict can therefore only cost that one pilot.
The Scorekeeper Decides
Under S7A §4.4.6, the decision to reject a track log belongs to the organiser, not to the software. A scorekeeper can accept a flagged tracklog in one action. GlideComp then scores it normally, its findings stay visible, and the competition's public audit log records the decision.
If GlideComp withheld your track, upload the right file. If the file you uploaded is the right one, speak to the scorekeeper.
Where the Thresholds Come From
A wrong zero for a pilot is worse than a bad file that gets through, so the thresholds come from real competition data.
In 4,762 archived tracks, the usual flight passes within 70 m of a turnpoint. The largest distance that an honest track stayed from every turnpoint was 45 km. The 100 km threshold is more than twice that distance.
The one-day grace has the same origin. In one archived task, three pilots of eighty had recorders stamped a day late. All three flew the task and GlideComp scored them normally, and one finished fourth, in goal. A rule that disqualified a one-day offset gave a zero to a podium flight.
In all 5,112 tracks that GlideComp holds, the checks withhold exactly one: a New Zealand flight submitted to a Victorian task ten days later.
Nothing Happens Silently
When a check fires, the pilot's report card names it, shows the numbers behind it, and gives the next step. The results table also labels a withheld track, so a zero never looks like a fault.
This is the same rule as track data cleaning: everything the system did on the way to a score must be visible.