Attribution is a contract term, not a courtesy

TallyAir does not generate a single position of its own. Every figure on every strip is somebody else’s observation, carried through with its errors intact — volunteer receivers, community aggregators, national registries, and a couple of open databases maintained by people who owe us nothing.

Several of those sources require attribution as a condition of use. Not as a nicety. As a term.

That distinction decided how the data sources page is written. Where a licence names a required credit, the credit is reproduced exactly as the licence words it, rather than paraphrased into house style. A summary of a licence term is a description of a contract, and the description is not the contract.

What that turned up

Reading the licences properly rather than skimming them produced a few things worth writing down:

ODbL separates a derived database from a produced work. Both adsb.lol and OpenFlights are ODbL 1.0. The share-alike obligation attaches to publicly distributing a database built from the source. Displaying records is a produced work, which carries attribution only. TallyAir displays; it does not redistribute a database. That is a position, and the page marks it as TallyAir’s position rather than as something the licensor has agreed to.

One source is non-commercial. openAIP’s airspace data is CC BY-NC 4.0. That is a real constraint on what the app can become, not a footnote, and it is named explicitly in the terms of use rather than buried in a list.

The warranty disclaimers say what a strip is better than we could. adsb.lol’s own disclaimer describes exactly the thing TallyAir draws: best-effort data, from sources the aggregator may not control, with no guarantee of integrity or accuracy. It is quoted at length on the page for that reason. Nothing we could write in our own voice would be as convincing as the upstream provider saying plainly that this is not a source you should bet anything on.

That is also why the operational disclaimer in the terms is not lawyer throat-clearing. It is downstream of what the data actually is.

Feeding back

Waygate Technologies runs a receiver that feeds several of these networks. It does not settle anything legally — feeding a network does not buy you a different licence — but it seemed worth doing, given the whole app is built on other people having done it first.