ADS-B aircraft surveillance from space
LEO satellites carrying 1090 MHz receivers decode ADS-B Out transmissions from aircraft anywhere on Earth, including oceans and polar regions where ground radar cannot reach. The technique extends global air traffic awareness but carries real latency and signal-collision constraints that buyers must understand before specifying it.
Sensors
- Aireon (hosted on Iridium NEXT): 66 operational Iridium NEXT satellites each carry an Aireon ADS-B payload. Global coverage including poles. Reported position latency of approximately 1 second to Aireon's ground network, making it the closest space-based ADS-B system to real-time. Used operationally by NAV CANADA, ENAV, IAA and others for oceanic ATC separation.
- Spire Aviation ADS-B: Spire operates more than 100 LEO satellites, a subset of which carry 1090 MHz ADS-B receivers alongside GNSS radio occultation payloads. Global revisit is frequent but not continuous; typical message latency for historical feeds is minutes rather than seconds. Suited to analytics and flow monitoring rather than live separation.
- exactEarth ADS-B (now part of exactEarth / Spire portfolio): exactEarth pioneered space-based ADS-B commercially before its acquisition. Its satellite constellation contributed to global aviation data feeds. The underlying signal-decoding approach is the same 1090 MHz squitter standard; archive depth extends back to the mid-2010s, useful for historical route and traffic studies.
What ADS-B Out actually broadcasts, and why space can hear it
ADS-B Out is a mandate, not a courtesy. ICAO Annex 10 and regional regulations require most commercial aircraft to broadcast a 1090 MHz Mode S Extended Squitter roughly twice per second. Each squitter carries ICAO 24-bit aircraft address, GPS-derived position, altitude, velocity vector and identification. The signal radiates omnidirectionally at up to 500 watts, which is enough for a receiver in low Earth orbit at 500 to 800 km altitude to detect it cleanly, provided the geometry is right.
Ground-based ADS-B receivers work well within line-of-sight, typically 400 to 500 km at cruising altitude. Over the North Atlantic, the South Pacific and polar routes, there is no ground infrastructure. A LEO satellite passing overhead sees those same aircraft from above rather than from the side, and the geometry is favourable: a cruising aircraft at 12 km altitude is well within the satellite's field of view for several minutes per pass.
The signal-collision problem: why space-based decoding is harder than it looks
A ground receiver in rural airspace might see a handful of aircraft simultaneously. A LEO satellite at 600 km altitude has a footprint roughly 6,000 km in diameter at the horizon. Over busy airspace such as the North Atlantic Organised Track System, that footprint can encompass hundreds of aircraft all squitting on the same 1090 MHz frequency at the same time. The resulting packet collisions, known in the literature as fruit (False Replies Unsynchronised In Time), corrupt a significant fraction of received messages.
Directional antennas reduce the problem by narrowing the effective field of view. Aireon's payloads on Iridium NEXT use phased-array antennas that can be steered to reduce simultaneous reception angles. Spire uses smaller patch antennas. Neither approach eliminates fruit entirely; published studies suggest message decode rates over dense airspace can fall to 60 to 80 percent of squitters transmitted, depending on traffic density and antenna design. The practical consequence is that position updates for any individual aircraft may arrive with gaps. For oceanic surveillance where aircraft are well separated, this is manageable. For dense terminal airspace, it is not.
Latency: the gap between surveillance and separation
Aireon is the only operational system that claims near-real-time delivery, quoting approximately one-second latency to its network operations centre. That figure reflects the Iridium constellation's inter-satellite links, which relay data pole-to-pole without waiting for a ground station pass. NAV CANADA and partner ANSPs use Aireon data for oceanic separation under ICAO standards, reducing longitudinal separation minima from 80 nautical miles to 30 nautical miles on some North Atlantic tracks.
Most other space-based ADS-B providers operate store-and-forward architectures. A satellite collects messages over a pass, then downlinks them when it next reaches a ground station. Latency ranges from a few minutes to fifteen or twenty minutes depending on ground network density. This is entirely adequate for post-flight analysis, flow modelling, emissions estimation and regulatory compliance monitoring. It is not adequate for live ATC separation, and no reputable provider claims otherwise. Buyers conflating the two categories will be disappointed.
What the data reveals beyond position
ADS-B messages contain more than latitude and longitude. Altitude (barometric and geometric), ground speed, track angle, vertical rate and the aircraft's ICAO identifier are all present in standard squitters. With a full message history, analysts can reconstruct actual flown routes, compare them against filed flight plans, compute fuel-burn proxies from altitude and speed profiles, and identify diversions or holding patterns.
Emissions estimation is a growing application. The ICAO Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) requires carriers to report CO2 emissions. Space-based ADS-B provides independent trajectory data against which reported emissions can be cross-checked. The method is not exact, as fuel burn depends on aircraft weight and engine state that ADS-B does not carry, but published models such as BADA (Base of Aircraft Data) allow reasonable estimates when combined with aircraft type from the ICAO address.
Search and rescue is another operational use. When an aircraft deviates from its last known track, the historical ADS-B record establishes the last confirmed position, narrowing the search area substantially compared to the pre-ADS-B era.
Honest limits: what space-based ADS-B cannot do
ADS-B depends on the aircraft transmitting. Aircraft without functioning transponders, transponders switched off, or operating below the equipage mandate (light general aviation in many regions, military aircraft almost universally) are invisible. Space-based ADS-B is not radar; it is a cooperative system. It detects willing participants only.
Coverage gaps persist at very low altitudes. A helicopter at 300 metres above terrain may not be visible to a satellite even if it carries a transponder, because the signal geometry places it below the satellite's effective receive angle. Message decode rates also degrade near the poles where Iridium provides good coverage but some store-and-forward constellations have sparser ground station access. And while Aireon's latency is impressive, even one-second delivery introduces a position age that makes it unsuitable for final approach or terminal sequencing. The system is designed for en-route oceanic and remote surveillance, and that is where it performs.
Analytics applications and where Satellize fits
Space-based ADS-B data is raw material. The value comes from what is done with it: route efficiency analysis for airlines, traffic flow modelling for airspace designers, emissions compliance monitoring for regulators, and anomaly detection for governments that want to know when aircraft deviate from expected corridors over sovereign territory.
Satellize builds analytics on top of licensed ADS-B feeds for government and enterprise clients, combining trajectory data with other space-sourced layers where relevant. The same analytical infrastructure that supports the Kingdom of Tonga crop-estimation programme handles time-series geospatial data at scale, and ADS-B trajectory feeds are a natural fit for that architecture. Clients seeking to monitor airspace over remote exclusive economic zones or to build independent emissions audit capability are the natural buyers for this type of work.
Typical figures
| Signal frequency | 1090 MHz (Mode S Extended Squitter, 1090ES) |
| Squitter broadcast rate | Approximately 2 per second per aircraft (ADS-B Out standard) |
| Satellite altitude (typical) | 500 to 800 km LEO |
| Satellite footprint diameter | Up to ~6,000 km at horizon; narrowed by directional antennas |
| Latency (Aireon / Iridium NEXT) | ~1 second to network operations centre (inter-satellite link architecture) |
| Latency (store-and-forward constellations) | Typically 5 to 20 minutes depending on ground station access |
| Position accuracy | Derived from aircraft GPS; typically better than 10 m horizontal (NACp ≥ 9 for compliant aircraft) |
| Message decode rate over dense airspace | 60 to 80% of transmitted squitters (fruit / packet collision dependent) |
| Coverage | Global including oceanic and polar; cooperative aircraft only |
| Archive depth | Mid-2010s onward for commercial providers; Aireon operational data from 2019 |
Analytics Satellize can run
| Oceanic route deviation alerts | Trajectory reconstruction from decoded ADS-B message sequence; comparison against filed ICAO flight plan corridors | Alert feed with aircraft ICAO ID, deviation distance and last confirmed position; delivered as JSON or GIS layer |
| Airspace traffic flow report | Aggregated track density analysis over defined airspace volumes and time windows; published flow-modelling methods (e.g. EUROCONTROL STATFOR methodology) | Periodic PDF report with traffic count, altitude distribution and peak-hour analysis; optional GIS heatmap layer |
| Emissions proxy estimation | BADA-class fuel-burn modelling applied to reconstructed trajectories; aircraft type resolved from ICAO 24-bit address lookup | Per-flight and fleet-level CO2 proxy estimates in CSV; suitable for CORSIA cross-check workflows |
| Sovereign airspace monitoring dashboard | Continuous ingestion of licensed ADS-B feed; flagging of aircraft entering defined EEZ or FIR polygon without expected flight plan correlation | Web dashboard with live and historical track replay; configurable alert thresholds by airspace zone |
| Search and rescue last-known-position report | Retrospective query of ADS-B archive for specified ICAO address; extraction of final confirmed position, altitude and velocity vector | Single-page incident report with track map and uncertainty radius estimate; delivered within agreed SLA |
| Historical route efficiency benchmarking | Actual flown distance versus great-circle distance comparison across carrier or route cohort; altitude profile analysis for cruise efficiency | Benchmarking spreadsheet and summary report; suitable for airline operations or regulatory input |
Who does the work
We can get this done for you. Satellize runs its own analyst desk and a strong science team. You do not buy a data feed and work out what it means; our people source the imagery, run the analysis described on this page, and hand you the answer with its confidence limits stated. Discuss this requirement.