Practical guide
How to analyze an XC flight from an IGC file
September 09, 2026
To analyse an XC flight from an IGC file, check track continuity first, then compare distance, altitude, climbs and transitions. Replay helps connect those numbers to the different stages of the flight.
What does an IGC file contain?
IGC B-records contain UTC time, position and altitude fields. Recording interval, fix validity and available sensors depend on the recorder.
Check which altitude is available and reliable: pressure and GNSS measurements have different limitations and should not be treated as interchangeable without checking.
What are the six things to read after an XC flight?
A distance flight is not judged by kilometres alone. After every XC it pays to look at six numbers, because they tell you where you gained and where you lost time.
- Distance: distinguish track length from calculated XC or triangle distance.
- Ground glide ratio: horizontal distance divided by altitude lost over the selected segment; wind and rising air affect the result.
- Climb rate: altitude change divided by duration, in m/s; it depends on the selected segment and data quality.
- Altitude: recorded maximum and gain in climbing segments; the track alone does not determine cloud base.
- Duration and speed: check which flight phases are included and compare equivalent intervals.
- Time climbing and transitioning: describes the flight distribution without independently grading efficiency or decisions.
How does RSFly.app read your IGC?
Free includes the logbook, essential statistics and Standard 2.5D Replay. Plus adds cinematic 3D Replay, detailed analysis, comparisons and exports. The Plans page describes current availability and terms.
Replay displays track samples and interpolates movement between them. Terrain and camera add context; the scene is neither a video recording nor an exact measurement of ground clearance.
Apply it to your flight
Free includes the logbook, essential statistics and Standard 2.5D Replay. Plus adds cinematic 3D Replay, detailed analysis, comparisons and exports. The Plans page describes current availability and terms.
- Open the IGC file in the logbook and check its date, duration and track continuity.
- Choose a climb or transition and compare time, altitude and replay over the same interval.
- Record observations and compare flights in similar conditions, keeping data separate from interpretation.
In short
- IGC B-records contain UTC time, position and altitude fields. Recording interval, fix validity and available sensors depend on the recorder.
- Distance: distinguish track length from calculated XC or triangle distance.
- Compare segments and flights with similar conditions and recording quality. Observed differences suggest debrief questions without automatically isolating the effect of pilot technique.