IGC data quality: the reliability floor for every metric

Every analysis you build on top — thermal strength, glide ratio, safety score, the anonymous pool — is only as reliable as the raw track. That's why Variograph shows how the file was recorded in its own panel.

Four things it checks

• Sampling rate — the typical time between fixes. 1 s/fix is ideal; 5 s/fix is coarse and lowers thermal resolution.
• Largest dropout — gaps where the logger dropped data. A 135-second gap hides the climb in that window.
• GPS spikes — physically impossible jumps (unrealistic speed or climb). A few are normal; many mean a noisy track.
• Barometer — is a pressure-altitude channel present? A baro-equipped logger gives more accurate vertical data.

Level: Good / Fair / Poor

These indicators reduce to a single level. For example, 1 s sampling + no gaps + no spikes → Good; a 135 s dropout → Poor.

Why care?

A "best glide 1:20" computed from poor data may not be real — it could be an artifact of a dropout or a GPS spike. Seeing the quality tells you how much to trust the numbers. The same holds for net vario and the wind profile from thermal drift: coarse sampling blinds both.

Quality is not the same as signature

Data quality measures how well the track was recorded; the digital signature (G-record) tells you whether the file was modified after recording. A file can be signed but low quality, or unsigned but flawless.

Where?

In the Data Quality panel in Advanced Analysis → Overview, with a coloured level badge. Head to the dashboard to upload a new flight.