Layer400 data sources and measurement limits
Follow a broadcast from receiver to map, and understand identity, coverage, timestamps, height references, test signals and the limits of recorded tracks.
By Layer400 · Reviewed
From radio to map
Layer400’s contributor receivers listen for supported drone Remote ID and aircraft ADS-B broadcasts. A station decodes reports locally and sends observations to the network. The public map is a processed view of received information, not a direct inventory of every aircraft in a region.
- Broadcast
A compatible vehicle transmits. - Receiver
A local station hears and decodes it. - Network
Reports are accepted and processed. - Map
Available positions form visible tracks.
A break at any stage can leave a gap. Receiver health, accepted observations and public tracks are related measurements, not the same count.
Identity is a field, not a conclusion
A Layer400 public reference is distinct from a manufacturer serial, aircraft registration or operator registration. Where aircraft reference data is available, the interface can add model, type, registration and airline information. Availability varies; an unidentified track must not be given a guessed identity.
Public references may rotate. Do not merge separate recordings solely because a public reference looks similar. Broadcast fields and lookup results can be incomplete or erroneous. The account and receiver-management areas are private and are not part of the searchable public information site.
Time and movement
Check the observation timestamp, not just when you opened the page. Reception delays, interrupted uploads and playback loading can affect the apparent order of events. A smooth marker animation is display behaviour; the report remains the evidence.
First and last received points are not confirmed departure and arrival locations. Gaps in a trail are missing evidence. A partly loaded history window is not a full recording, even if the visible line looks continuous.
Height and distance
Height above ground, mean-sea-level altitude, geometric height and pressure altitude are different quantities. Use the label supplied with the value. A conversion from metres to feet does not convert between height references.
The observed proximity method uses a qualified common vertical reference when available and explicit horizontal distance otherwise. A close pair of symbols is not, by itself, a confirmed near miss.
Coverage, tests and responsible interpretation
Coverage depends on where receivers are operating, their antennas and hardware, obstructions, interference and the supported transmissions. Some vehicles will not be visible. Do not describe the map as complete surveillance or use an empty area as proof that no drone was flying.
TEST broadcasts remain marked because their positions may be programmed rather than physical aircraft positions. Nearby IDs and possible co-moving groups do not establish intent or coordinated activity. Layer400 is a source of received information, not an official incident classification.
See the data notice and corrections process. To improve local reception, connect a receiver; to inspect the current view, use the map and playback guide.