What we learned parsing Norway's ED-269 drone-zone file

Many ED-269 feeds wrap their zones in a container object. Norway's download is a plain JSON array of zones. A parser should accept both shapes rather than assume the wrapper.

In the file we first parsed, 4,341 zones became 5,297 restrictions, because 317 zones carry several volumes and one nature reserve carries 265 of them. If you count rows to describe coverage, you are counting how the publisher chose to cut the geometry, not how many places are restricted.

The file has no permanent flag, no applicability and no dates. Every zone has to be treated as permanent with no window, and that is an assumption to state, not a fact the data gives you.

Every volume runs from the ground to 300 m above ground level, in metres. The restrictions fall into two kinds: 1,234 zones require authorisation and 3,107 are conditional, meaning coordination is required. The messages are in Norwegian and are worth keeping verbatim rather than translating.

Two volumes have a ring with fewer than three distinct points, which is not a polygon. A parser that is happy with them will hand a geometry check something it must reject, so validate geometry after parsing, per volume, and let the zone's other volumes through.

The coordinates reach 81° N, so a country bounding box drawn around the mainland leaves the Svalbard zones outside it. If you filter by a box, decide on purpose whether those belong.

The GeoPilot API converts ED-269 to GeoJSON in one call and reports unconvertible features and warnings instead of failing the whole document; the conversion guide has the request. For how the two standards differ, see ED-269 vs ED-318.

A conversion changes the format, not the facts. Check any zone against the publisher's own service before you rely on it.