Transparency panel — known caveats in this dataset, with real counters rather than hidden assumptions.

How airlines are identified. Each aircraft is matched to an airline via its live radio callsign first — the most reliable signal we have. When no callsign is available, we fall back to external registry lookups, which are occasionally wrong or outdated. On 22 July 2026 we audited every aircraft with conflicting airline labels across sightings and corrected ~1,070 aircraft (~6,700 flights) where a live callsign contradicted a weaker guess. One editorial call worth flagging: Malta-registered (9H-) aircraft split between two real Ryanair Group entities with different fleets — Malta Air (Boeing 737) and Lauda Europe (Airbus A320/A321) — we now separate them by aircraft type rather than lumping both under "Ryanair".

Ambient PM sensor readings captured alongside each flight event — a timing reference, not proof that aircraft caused the reading (a barbecue or cigarette on the terrace affects it just as much).