Air traffic flow analysis from spaceborne ADS-B
Ground radar stops at the coastline. Spaceborne ADS-B receivers on Spire Global and Aireon/Iridium NEXT reconstruct full oceanic and polar trajectories, exposing route utilisation and congestion that terrestrial systems simply cannot see.
Sensors
- Aireon ADS-B on Iridium NEXT: 66 operational satellites in six polar orbital planes at roughly 780 km altitude. Each hosts a hosted-payload ADS-B receiver built by Harris Corporation. Global coverage including poles; published update interval for a single aircraft is approximately 8 seconds over oceanic airspace. Declared position accuracy follows the aircraft's own GPS, typically better than 10 m horizontally.
- Spire Global spaceborne ADS-B: Constellation of over 100 small LEMUR-2 satellites in LEO at mixed inclinations and altitudes between roughly 400 and 600 km. Provides complementary coverage and independent cross-check of Aireon data; revisit cadence varies by latitude and constellation size but is broadly comparable over oceanic regions.
- Aircraft ADS-B transponders (1090 MHz ES): The signal source, not a satellite sensor. ICAO mandates 1090 MHz Extended Squitter on aircraft above certain weight and airspace classes. Transponders broadcast position, altitude, velocity, ICAO 24-bit address and flight ID at nominally 2 Hz, though the actual rate varies by avionics manufacturer and mode.
Why the ocean is a blind spot, and why that matters commercially
Ground-based primary and secondary surveillance radar has a practical range of around 450 km from the antenna. The North Atlantic, the South Pacific, the Arctic and most of the Indian Ocean lie well beyond any chain of antennas. For decades, oceanic separation standards were set at 50 or even 100 nautical miles laterally and 10 minutes longitudinally, not because those gaps were safe in some absolute sense, but because controllers had no better information. Aircraft filed position reports by HF radio on the hour.
The commercial consequence is large. Oceanic tracks are published daily by Shanwick and Gander oceanic control for the North Atlantic, and by equivalent authorities elsewhere. Airlines that cannot obtain their preferred track fly longer routes or at suboptimal altitudes, burning more fuel. The International Air Transport Association has published estimates of avoidable fuel burn attributable to oceanic separation inefficiency, though the precise figures shift with traffic volumes. The point is directional and well established: better surveillance data translates directly into tighter separations, more flexible routing, and measurable fuel savings across a fleet.
What 1090 MHz looks like from 780 km up
ADS-B Extended Squitter is a 112-bit pulse-position-modulated burst at 1090 MHz. Each burst lasts about 120 microseconds. From the ground, a receiver is typically within line-of-sight of a modest number of aircraft. From a satellite at 780 km, the geometric footprint covers roughly 6,000 km in diameter, which over the North Atlantic in peak hours means hundreds of aircraft are simultaneously in view.
That density creates two distinct problems. The first is message collision: when two or more aircraft transmit simultaneously, their bursts overlap at the receiver and neither decodes cleanly. Collision probability rises roughly with the square of the number of visible aircraft. Aireon's published technical work acknowledges this and describes multi-message decoding techniques, but over the densest continental airspace, collision rates can degrade detection probability meaningfully. Oceanic regions, where traffic is sparser, are where spaceborne ADS-B performs best and where the surveillance gap is also largest. The fit between the technology's strengths and the operational need is genuinely good.
The second problem is Doppler shift. A satellite moving at roughly 7.5 km/s relative to a transmitting aircraft imposes a Doppler offset on the 1090 MHz carrier that can reach several kilohertz. Receivers must compensate for this in real time to decode correctly. Both Aireon and Spire have published descriptions of their signal processing approaches. The corrections are tractable but they add complexity and represent a real engineering constraint that distinguishes spaceborne from terrestrial ADS-B reception.
Reconstructing trajectories and flow patterns from decoded messages
A single satellite pass over an oceanic region yields a snapshot: a set of decoded position reports, each stamped with the satellite's own GPS-derived time and the aircraft's self-reported position. Chaining passes from multiple satellites, or from the Iridium constellation's continuous coverage, produces a trajectory. The trajectory can be compared against the filed flight plan to quantify lateral and vertical deviation, actual versus planned speed, and whether the aircraft achieved its requested flight level.
Aggregating trajectories across many flights and many days produces route utilisation statistics: which organised track slots are consistently full, which are underused, where aircraft cluster at particular waypoints, and how congestion propagates through a region when weather forces track consolidation. These are the inputs to airspace capacity analysis. Air navigation service providers use exactly this kind of aggregated data to justify track system redesigns or to negotiate revised separation minima with ICAO.
One honest caveat: spaceborne ADS-B tells you what the aircraft reported. It does not independently verify position. A malfunctioning or spoofed transponder will produce plausible-looking data. Cross-referencing against independent sources, such as HF position reports or, where available, overlapping radar coverage at oceanic boundaries, is necessary for safety-critical applications. For commercial flow analysis, the self-reported data is generally sufficient.
Polar routes: the case where spaceborne ADS-B has no terrestrial substitute
Transpolar routes between North America and Asia, and between Europe and Asia, have grown substantially since Russian airspace restrictions altered preferred routings after February 2022. These routes pass through latitudes above 80 degrees north, where geostationary communication and surveillance satellites have no useful view angle, and where ground infrastructure is essentially absent.
Iridium NEXT's polar orbital planes give Aireon genuine continuous coverage at all latitudes including the poles. This is not a marginal improvement over the previous situation; it is the difference between having surveillance and not having it. The Canadian and American ANSPs were among the early adopters of Aireon data for exactly this reason, enabling reduced vertical separation minima on polar tracks that were previously managed with far wider buffers.
Limits, collision rates, and what the data cannot tell you
Over continental Europe or the eastern United States, spaceborne ADS-B is largely redundant with dense ground networks and adds little. Its value is specifically in the gaps. Even within those gaps, message collision rates over the busiest oceanic entry and exit points, where many aircraft converge on the same waypoints, can reduce the probability of decoding any given message from a specific aircraft on a given satellite pass. Aireon's own technical documentation describes detection probabilities rather than certainties, and the figures depend on traffic density and antenna design.
Spaceborne ADS-B also cannot detect aircraft that are not equipped with ADS-B Out, or that have switched their transponders off. Older freighters operating below mandatory equipage thresholds in some regions, and military traffic, are invisible. For a complete picture of all airborne objects, ADS-B data needs to be fused with other sources, a topic covered in the dark vessel detection and RF monitoring pages in this library.
Satellize ingests both Spire and Aireon-derived data streams under client licence and applies trajectory reconstruction and flow-aggregation analytics. The Overhead column has covered polar route shifts in the context of geopolitical airspace changes, which gives a sense of the analytical framing we bring to this data.
Typical figures
| Signal frequency | 1090 MHz (Extended Squitter, ICAO Annex 10) |
| Burst duration | ~120 microseconds per ADS-B message |
| Nominal transmit rate (aircraft) | ~2 Hz; varies by avionics manufacturer |
| Aireon update interval (oceanic) | ~8 seconds per aircraft, published by Aireon |
| Satellite altitude (Aireon/Iridium NEXT) | ~780 km |
| Satellite altitude (Spire LEMUR-2) | ~400–600 km |
| Geometric footprint per satellite | ~6,000 km diameter at 780 km altitude |
| Position accuracy (source) | Aircraft GPS, typically <10 m horizontal; not independently verified by satellite |
| Coverage | Global including poles (Aireon); global with variable revisit (Spire) |
| Key limitation | Message collision probability rises with traffic density; performance best in oceanic/polar regions |
Analytics Satellize can run
| Aircraft trajectory reconstruction | Sequential Kalman filtering of decoded ADS-B position and velocity reports across multiple satellite passes | Per-flight trajectory file (GeoJSON or KML) with altitude, speed and deviation from filed plan |
| Oceanic route utilisation index | Spatial binning of trajectories onto organised track structure; frequency and load-factor statistics per track slot | Daily or weekly CSV report of track slot utilisation by hour and direction, suitable for ANSP planning |
| Airspace congestion heatmap | Kernel density estimation of aircraft positions at fixed altitude bands over a defined oceanic region | Gridded GeoTIFF or GIS layer showing congestion intensity by hour, archivable for trend analysis |
| Polar route shift monitoring | Automated detection of significant changes in centroid latitude of transiting traffic over user-defined polar corridor | Alert feed with weekly summary report; flags route consolidation events for operational or commercial teams |
| Flight-level efficiency analysis | Comparison of filed versus achieved flight level per trajectory segment; statistical aggregation by airline, aircraft type and route pair | Tabular report for fleet or route planning teams; highlights systematic altitude penalties on specific routes |
| Message decode quality assessment | Per-pass signal quality metrics derived from collision rate estimation and gap analysis in decoded message sequences | Data quality confidence layer accompanying each trajectory product; flags low-confidence segments explicitly |
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.