Supported sources · IGC file

Free flight’s logbook, read line by line.

An IGC file is a text file: one line per point, a header, two altitudes and, often, extra columns nobody ever looks at. YouMetry reads all of them and puts them on screen, over your camera’s video.

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What is inside an IGC file

The B records, one per point: UTC time, latitude and longitude in degrees and thousandths of a minute, point validity, then two altitudes in metres — pressure and GPS.
The HFDTE header, which gives the flight date — in both spellings, the old one (HFDTE150626) and the new one (HFDTEDATE:150626,01).
The pilot, the launch site and the glider type (HFPLT, HFSIT, HFGTY headers), carried into the session information.
The extensions: an I line declares columns appended to every B record, a J line does the same for the more widely spaced K records — which is where the wind lives.

The two altitudes, and why they matter

Pressure altitude is smooth: a barometric sensor does not jump, and a clean vario comes from it. But it refers to the standard atmosphere, 1013.25 hPa, so it drifts from the true altitude with the day’s QNH. GPS altitude is noisier, but it is the real height above sea level.

So YouMetry takes both: pressure for the vario, GPS for the altitude shown above sea level. And if your vario has no pressure sensor — it then writes zeros — everything comes from the GPS, with nothing for you to set.

The extra columns, read one by one

True and indicated air speed (TAS, IAS) and the compensated vario (VAT), converted into the app’s own units.
Wind: direction (WDI) and speed (WVE, WSP). A K line’s value is held until the next one, just as the instrument displayed it — and the direction is never interpolated, so that going from 350° to 10° does not swing round through the south.
Ground speed (GSP): the GPS chip’s Doppler speed, better than one computed between two fixes, and preferred whenever it is present.
GPS quality: accuracy (FXA) and satellite count (SIU), displayable like any other value.
And the rest: engine noise (ENL, MOP) and RPM for a paramotor, vertical acceleration (ACZ), outside air temperature (OAT), and the LAD / LOD columns that refine the position down to a decimetre.

Where the file comes from

Every paragliding or hang-gliding vario writes IGC: XCTrack on a phone or a dedicated Android device, Skytraxx, Syride, Flymaster, Naviter Oudie, Flytec, Open-Vario instruments. It is also the only format read by the platforms where flights are submitted — XContest, France’s CFD, the DHV-XC, Leonardo and the OLC: the file you already upload there is exactly the one YouMetry opens.

YouMetry connects to none of those platforms and sends nothing to them: it reads the file on your disk, and that is all.

How to do it

Get the .igc file off your vario — the one you would submit to XContest.
Open your video in YouMetry and drop the file onto it: the world switches to paragliding by itself, once per file — you can go back to another vehicle, and the file will not take it away again.
Line the data up with the picture using the offset: the vario’s clock is UTC, the camera has its own.
Export the burned-in video, or a transparent layer for your editing software. You can also see it all first in the online trial, which reads .igc files with nothing to install.

What the format does not give

A vario usually writes one point per second. That is enough for the flight and the 3D view, thin for a gauge moving every frame: the track is smoothed between points, without moving the turns.
The extra columns exist only if your instrument writes them: with no air-speed extension, there is no air speed — the file does not hold it, and nothing invents it. A code YouMetry does not know is simply left aside.
No three-axis acceleration, no car engine RPM, no laps: an IGC is a flight track. For the rest there are the other sources, which combine inside the same project.
A file with no date header still reads, but the app says so: only the time can then be used for syncing. And a file without at least two B records is refused with a clear message, rather than half-opened.

Good to know

IGC times are in UTC, and a flight crossing midnight restarts at 00:00:00 in the file: YouMetry reads that as one day more, not as going backwards.
The file is never modified: YouMetry reads it, and lines it does not understand — signatures included — are left aside without touching the original.
Paragliding mode is on Mac and Windows. The mobile app stays car and motorcycle.

Questions

What is the difference between an IGC and a GPX?

A GPX carries one altitude only, the GPS one. An IGC carries two — pressure and GPS — and may carry wind, air speed and GPS quality besides. That is why a vario derived from an IGC is smooth where one from a GPX is jumpy. If your instrument writes GPX only, YouMetry reads that too: you lose the extra columns, not the flight.

What appears on screen from an IGC?

The vario, −5 to +5 m/s, altitude above sea level, ground speed, heading, distance from launch, the flight’s track, and the glide ratio — distance covered per metre lost, which goes silent when it would mean nothing. The flight also replays in 3D over the real terrain, wing included: the paragliding page shows that in detail.

Is there a lap timer, as on a race track?

No, and that is deliberate: free flight is not raced in laps. Take-off and landing, on the other hand, are found on their own — from ground speed, not altitude, because a paraglider often lands far below its launch.