Air Traffic Density
Every 30 minutes the observatory asks two volunteer networks (adsb.lol and adsb.fi) how many aircraft are broadcasting inside a 120-nautical-mile volume above each of ten major hubs, and stores one count per hub. Airspace activity is one of the few continuously published, hard-to-stage measures of real movement. Counts that depart from a hub's own recent pattern can accompany weather closures, airspace restrictions, or unusual demand.
Current reading
No reading available in this range. This is not a zero reading.
Ten sampled volumes: London, New York, Frankfurt, Dubai, Singapore, Tokyo, Sydney, Los Angeles, São Paulo and Johannesburg. This is not global coverage.
- Collector availability
- Unavailable
- Collection freshness
- No successful collection recorded.
Historical comparison
Not enough data yet. No observations are available in this range.
Interpretation
Not enough data yet. The available history cannot establish whether this reading is typical or unusual.
- A hub-wide drop over several runs alongside weather or airspace disruption
- A sustained rise against the hub's own recent pattern
Not established. Aviation activity follows demand, weather and disruption. This detector is descriptive, and its counts say nothing about why aircraft are flying. Source-reported severity, statistical deviation and real-world risk are different questions. This reading does not independently support a hypothesis about intent or cause.
Evidence and limitations
- Cadence and latency
- Collection is scheduled every 30 minutes. Collection cadence is not source latency; no measured end-to-end latency is provided here. Source publication and revisions can delay what is visible.
- Receiver drop-out or a network hiccup looks like a fall in traffic
- A single large event, holiday or airshow lifts counts without any wider meaning
- Coverage depends on where volunteer receivers are; a quiet count can mean few receivers, not few aircraft.
- Counts are instantaneous snapshots of a sampled volume, not totals of flights or aircraft-hours.
- Aircraft that switch off their transponder — some military and some private operators — are invisible to this source.
- Individual aircraft are not stored here; business jets and military aircraft have their own detectors.
- Only ten hubs are sampled; activity elsewhere does not affect the reading.
The history contains stored count snapshots, not individual aircraft positions or flight tracks. Live aviation positions shown elsewhere are not stored history.
Technical detail
- Measurement definition
- Each observation is one snapshot: the number of aircraft with a live position inside that hub's sampled volume at the moment of collection. The value is the count; the stored position is the centre of the volume, not an aircraft.
- Raw metric
- active_aircraft
- Method
- Hubs are split between adsb.lol and adsb.fi, always the same hub to the same network, read in parallel at most one request per second per network. Counts are stored as observations and also recorded as a snapshot metric sample, which the baseline compares against the hub network's recent history. A run that fails is recorded as a failed run; no count is invented for it.
- Stored observations
- 0
Normal versus unusual
A baseline cannot yet be established. The observatory needs more history before it can say what "normal" looks like for this signal, so no anomaly score is shown.
The label the publishing agency assigns (e.g. NWS 'Severe'). Shown verbatim.
How far today's value sits from this signal's own history. Says nothing about consequences.
A judgment the observatory does not make. Consult official sources for safety decisions.
Observations in range
No observations stored for this range.
Recent collection runs
- · running · 0 stored
- · running · 0 stored
- · running · 0 stored
- · failed · 0 stored · Interrupted before finishing (no result recorded)
- · failed · 0 stored · Interrupted before finishing (no result recorded)
- · failed · 0 stored · Interrupted before finishing (no result recorded)
- · failed · 0 stored · Interrupted before finishing (no result recorded)
- · failed · 0 stored · adsb.lol responded 429 for London
How this works
We count all aircraft broadcasting their position inside fixed circles of airspace around busy hubs, using the adsb.lol volunteer network, one area per second as the network asks.
"Normal" is the total at the same half-hour of the week in earlier weeks (at least 3 weeks), because air traffic follows weekly schedules. If any area fails, that run's total is not recorded at all, since a partial total isn't comparable.
Limits: this measures how busy a few hubs are, not any particular kind of flight. The business-jet and military signals are better for watching unusual movement. Map rings mark the middle of each area, not any aircraft.
FAQ
- Why did this layer show 0?
- On 1 Nov 2026 the source refused our requests for sending too many at once. Collection now spaces requests out and retries once.
- Is this a private-jet indicator?
- No. It counts all aircraft. See Business Jets Airborne for that.