Safety and forecast limitations
How to read Flywhen without asking a forecast to know more than it can.
GO FLY and Good to fly mean the forecast passed the limits selected in Flywhen. They do not mean a flight is authorized, legal or guaranteed safe.
Flywhen is a planning aid
Flywhen compares forecast values with the aircraft, mission height and limits selected in the app. It helps identify promising hours and explains which forecast factor closed another hour.
Flywhen cannot see the conditions at your launch site. It cannot inspect your aircraft, know every obstacle, detect a temporary restriction, read a product label, confirm your certificate or permission, or decide whether conditions remain safe throughout an operation.
A forecast is not an observation
A weather model estimates the atmosphere on a grid. Even a high-resolution grid averages conditions across an area. Trees, buildings, slopes, shorelines, convection and narrow weather boundaries can make the actual site different from the model cell.
Forecast skill generally falls as lead time grows. A forecast can also be stale, delayed, incomplete or unavailable. Always check the model, resolution and age displayed by Flywhen, then verify current conditions on site before operating.
What a positive result means
A positive result means every enabled forecast check passed the limits saved on that device for that hour. It does not evaluate disabled checks, missing real-world hazards, airspace, permissions, maintenance, payload, route, people or regulations.
The selected limits may be wrong for the aircraft or operation. A manufacturer's maximum wind resistance is a product specification, not automatically a routine operating recommendation or a guarantee of safe operation. Your aircraft manual and a conservative operating plan control.
Wind changes with height and place
Surface wind is not necessarily the wind at the planned height. Flywhen uses direct model levels where available and clearly labels a proxy or interpolation where required. A model level is still a forecast for a grid cell, not a measurement along the flight path.
Structures and terrain can accelerate, channel or disturb wind. Wind at the controller can differ from wind near a roof edge, tower, tree line or ridge. Check conditions at the site and throughout the operating area.
Derived and unavailable values
Cloud base, density altitude, wind chill and some task measurements are calculated from forecast inputs. GNSS satellite and space-weather outputs depend on external orbital and geomagnetic data. A calculation can be precise without being accurate at the site. Missing data is not a safe reading.
Task profiles do not change the law
Mission profiles organize additional planning conditions. They do not expand aircraft limits, grant permission, or decide that an operation is suitable. Inspection, survey and cinematic work still require site-specific judgment.
Spraying guidance is not an application authorization. Use the specific product label, current local rules, on-site measurements, trained operator judgment and all required permissions. Flywhen does not determine whether an application is legal, effective or safe.
Before every operation
- Confirm the selected location, aircraft, task, height, units and limits.
- Check the forecast model, resolution, run age and any stale-data warning.
- Use official sources for weather, airspace, NOTAMs and restrictions.
- Follow the aircraft and controller manuals, including wind, temperature, battery and payload limits.
- Inspect the aircraft, batteries, propellers, controller, links and required safety equipment.
- Assess people, property, obstacles, terrain, visibility, precipitation and changing conditions on site.
- Confirm certificates, permissions, insurance and rules for the exact operation and jurisdiction.
- Do not operate, or stop the operation, whenever safety is uncertain.
Rules vary worldwide
Rules depend on country, region, aircraft, operation and authorization. Flywhen does not maintain a complete global rules database. For Canadian operations, consult Transport Canada drone safety and the current Canadian Aviation Regulations on minimum weather conditions. For United States operations, consult the Federal Aviation Administration UAS portal. Elsewhere, check the responsible aviation and other authorities where you operate.
Data sources have limits too
Forecast data is supplied through Open-Meteo, which does not guarantee accuracy, completeness, reliability or uninterrupted availability. Model data comes from public meteorological organizations identified in the app. Their data and Flywhen's presentation remain planning information, not a substitute for official preflight sources.
Read the full terms
The Flywhen Terms of Use contain the warranty disclaimer, user responsibilities and limits of liability. Questions: appsupport@deepdivesites.dev