What FlySight measures — and what it cannot see

What a recording contains

FlySight is a GNSS logger: several times a second, typically 5 Hz, it records the time, latitude and longitude, altitude above mean sea level, north, east and down velocity, and the receiver's own accuracy estimates. ^[1][2]

The velocity comes from the Doppler shift of the satellite signals, which is why speed is measured directly rather than worked out from positions. ^[1]

FlySight 2 can also record a sensor file with barometer, humidity, temperature and IMU data; the original FlySight records GNSS only. ^[1][3]

What is calculated from it

Ground speed is calculated from the north and east velocity, so it is speed over the ground with the wind included — not airspeed. ^[4][5]

Heading is the direction of travel over the ground, not where the canopy points; turn rate is the change of that heading per second. ^[4]

Height above ground (AGL) is the GNSS altitude minus a ground reference taken at touchdown in the same recording. ^[4][6]

Where the numbers lose precision

GNSS vertical error is typically a few metres, and sloping terrain or a poor vertical fix shifts AGL; heights are shown to the foot for readability, not because they are that precise. ^[6]

Heading becomes unreliable at low ground speed — below about 8 m/s — and a gap of more than 2 seconds between samples lowers confidence. ^[7]

Values with limited or unavailable confidence are left out of averages and baselines rather than replaced with guesses. ^[7]

What no GNSS logger can see

FlySight does not record toggle or riser position, harness input, the pilot's intent, other traffic, or the wind at the canopy or on the landing area. ^[8]

Angle of attack, lift and canopy trim are not measured directly either; any note about controls on a jump page is a tag entered by a person and labelled as such. ^[8]

Wind shown next to a jump comes from a station, an airport report or a weather model, so it is context rather than a measurement taken where you landed. ^[9]

Sources

Each statement above was checked against these sources on Oct 7, 2026. Link checks come from the site's source registry; sources are listed as cited, not endorsed or ranked.

1. Methodology — What FlySight measures
   SkyLara page — the sources behind it are listed on that page.
2. FlySight · www.flysight.ca
   checked Oct 7, 2026
3. Methodology — Data sources and import adapters
   SkyLara page — the sources behind it are listed on that page.
4. Methodology — What Canopy Intelligence derives
   SkyLara page — the sources behind it are listed on that page.
5. Glossary
   SkyLara page — the sources behind it are listed on that page.
6. Methodology — Height above ground (AGL)
   SkyLara page — the sources behind it are listed on that page.
7. Methodology — Uncertainty and confidence
   SkyLara page — the sources behind it are listed on that page.
8. Methodology — What FlySight does not measure
   SkyLara page — the sources behind it are listed on that page.
9. Methodology — Weather limitations
   SkyLara page — the sources behind it are listed on that page.

Every source we cite →