Paraglider assessments

The logic is intentionally simple and conservative. Launch suitability is weighted most toward safety, while thermal quality tries to describe whether the air actually looks active and usable. The result is meant as a quick summary of local conditions, not as an automatic go/no-go decision.

Launch suitability is mainly based on wind direction relative to site sectors, mean wind, gusts, gust spread, rain, night after sunset, and how stable the direction is. If the wind is outside a usable sector, if it is raining, if it is night, or if the wind becomes too strong, the assessment should clearly move toward caution or avoid.

Aligned is used when the direction is inside the green sector and the wind looks manageable. Caution is used when wind becomes noticeable, gusts rise clearly above mean wind, or direction shifts more than desired. Strong is used when mean wind is above 8 m/s, or when gusts rise more than 2 m/s above that threshold. Avoid is used for a red sector, outside a usable sector, when rain is falling at launch, less than 15 minutes after the latest rain, or after sunset.

When a current wind direction from Yr is available, it is compared with the direction measured by the station. If the smallest angular difference is greater than 100 degrees, the flight assessment shows a red hazard icon and “Avoid right now”.

Such a large difference may mean that the station is in rotor or another local reverse flow. The sensor can then appear to measure favourable wind straight into launch even though the prevailing wind actually creates tailwind. The check runs only when the measured direction is within a green or yellow sector. If the direction is in a red sector or outside the usable sectors, conditions are already assessed as unsuitable and the rotor rule is not used. The warning explains the difference and shows both directions. The rule requires both a local measurement and an Yr wind direction; missing Yr data does not produce a red warning by itself. Yr is a model forecast, so the warning is a conservative hazard signal rather than proof of rotor.

Thermal quality describes how organized and usable the air looks, not just how strong the wind is. It uses signs of surface heating, temperature trend, dew point spread, mean wind, gusts, and direction changes.

Clean requires clear thermal potential, limited gust spread, and relatively stable direction. Usable is used when several signals point the right way, but conditions do not look fully organized. Rough is used when wind is gustier, direction shifts more, or the wind is strong enough that lift will likely feel less organized. Flat is used when limited surface heating, rain, less than 15 minutes after the latest rain, night after sunset, or a very weak thermal signal suggests that the air is not really working. Rain, recent rain, and night set thermal potential to 0.

The flying summary combines launch suitability and thermal quality. Its main job is to prevent promising thermal signals from hiding poor or unsafe launch conditions.

Avoid right now is used when launch conditions are outside sector, in a hazard sector, in rain, less than 15 minutes after the latest rain, after sunset, or the wind is too strong. Good launch wind requires good launch direction, manageable wind, and organized air. Flyable but rough is used when there may be lift, but the wind looks disorganized. Stable / weak is used when wind is calm or thermals look suppressed. Watch conditions is used when conditions are partly promising, but not clear enough for a green light.

Bakvind uses what the local station actually measures: wind speed, gust, wind direction, temperature, dew point, humidity, pressure, light, UVI, and rain. Short history windows are also used to see whether temperature is rising and whether the wind looks stable or changeable. When Yr data is available, the current Yr wind direction is also used to detect a potentially dangerous direction conflict.

Some thresholds are made explicit to keep the assessments easy to understand. Mean wind above 5 m/s moves the assessment toward caution. Mean wind above 8 m/s is treated as strong. Gusts are allowed about 2 m/s more than the mean-wind thresholds before they move the assessment to the same level. Rain at launch always counts negatively, and a large spread between mean wind and gust is treated as a sign of more turbulent air.