Hiero

Heads-up Information for Enroute Readiness & Observation.

Hiero is a Flutter app for quickly finding flight-related information around nearby aerodromes. The app is designed for online and offline use, including Android-based writing tablets with color or monochrome displays.

Aeronautical data

Hiero fetches AIP documents and charts, NOTAMs, weather and SNOWTAMs directly from public sources, caches them for offline use, and falls back gracefully when a source fails. Highlights:

• AIP charts, including the German AIP VFR traffic circuit (Platzrunde) for VFR-only fields such as EDLS.
• Nearby NOTAMs: fields without their own NOTAMs surface NOTAMs from aerodromes within 50 NM.
• Weather with an OCR fallback to an aerodrome's website when no official METAR exists.

See Live data sources and diagnostics for the per-source behaviour, AIRAC cycle handling, and caching. A future central data publisher is described in data-platform.md.

Live aircraft

Hiero shows live ADS-B traffic near the reference point, both as a distance- sorted list and as rotating markers on the map. The nearby radius is configurable (10 / 25 / 50 / 100 NM, or the km equivalents) and the status line states how many aircraft are in range. For airline flights it resolves where each flight is coming from and going to — origin/destination airports and the operating airline — from a callsign route lookup, shown as a "from → to" card in the aircraft detail view and a compact chip in the list. See Live aircraft.

Disclaimer and languages

On first launch Hiero shows a one-time disclaimer: the information is provided on a best-effort basis, is not an official source, and must never be your sole source for flight planning or navigation. An "About, disclaimer & sources" screen (reachable from Settings) explains the data sources and licensing in readable, in-app Markdown.

The UI is available in Dutch, English, German, French, Italian, Polish, Spanish and West Frisian (Frysk), covering the main screen, the detail screens (weather, NOTAM, SNOWTAM, AIP charts/settings, openAIP field view, briefing summary, diagnostics, map settings) and the disclaimer/about screen. Frisian is provided on a best-effort basis.

Diagnostics

All network and parsing failures are recorded to an in-app diagnostics log (levels, categories, an in-memory buffer). A filterable diagnostics screen with copy-to-clipboard export is reachable from the settings sheet, so issues can be inspected or shared without a terminal. See Live data sources and diagnostics.

Map caching

The map uses OpenStreetMap tiles through flutter_map with built-in disk caching when supported on the device. The cache provider is warmed up at app start so the first map view is served from disk. Tiles are stored under the app documents directory and treated as fresh for a configurable window (7–30 days, default 7) before revalidation.

Tiles load only for the viewport the user is actively viewing while panning or zooming. Hiero does not prefetch or offer offline map downloads while it uses the public OpenStreetMap tile service. Offline maps require a dedicated provider or self-hosted service whose terms explicitly permit prefetching.

The map range (and all distances) use a configurable unit — nautical miles by default, with kilometres as an alternative, switchable from a toggle next to the range selector. Range options are 10 / 25 / 50 / 100 NM or 10 / 25 / 50 / 100 / 250 km; switching unit snaps the current range to the nearest round option in the new unit. A crosshair marks the exact map centre, and tapping the map adopts that point as the reference location, so a chosen point lands precisely rather than just beside where you aimed.

Website weather OCR

When no official METAR is available for a configured aerodrome, Hiero can extract an explicitly labelled, unofficial weather report from that aerodrome's website. OCR runs locally with open-source Tesseract on every supported platform. See OCR and source licensing for platform packaging, attribution, CORS, and source-permission requirements.