ADS-B aircraft tracking from space
LEO satellites receive 1090 MHz ADS-B transmissions to track aircraft over oceans and polar regions where ground radar cannot reach. Aireon, hosted on Iridium NEXT, is the only fully operational global system with published performance data.
Sensors
- Aireon (Iridium NEXT hosted payload): 66 operational LEO satellites at approximately 780 km altitude, each carrying an ADS-B receiver as a hosted payload. Provides global coverage including poles. Aireon has published position update rates of once per 8 seconds over oceanic airspace, with demonstrated 99.9% surveillance availability over the North Atlantic Track System.
- Spire Global ADS-B: Spire operates a constellation of 3U CubeSats in LEO carrying ADS-B receivers alongside GNSS-RO and AIS payloads. Coverage is global but revisit is less deterministic than Iridium-hosted solutions; latency to data delivery is typically a few minutes. Spire publishes aggregate flight data products rather than real-time surveillance feeds.
- exactEarth ADS-B (now part of exactEarth / Spire portfolio): exactEarth pioneered small-satellite ADS-B reception and published early collision-rate studies for high-density airspace. Its heritage data archive extends back to the mid-2010s, making it useful for historical traffic analysis over oceanic routes.
Why ground networks leave half the planet unseen
Ground-based ADS-B receivers and secondary surveillance radar share a fundamental constraint: line of sight. At cruising altitude, a receiver on the surface can detect an aircraft roughly 400 to 450 km away under ideal conditions. That sounds generous until you plot it against the North Atlantic, the South Pacific, or the Arctic. Those regions have no radar coverage whatsoever. Before space-based ADS-B, controllers managing oceanic traffic relied on procedural separation, meaning aircraft were kept 80 to 100 nautical miles apart laterally and 10 minutes apart longitudinally, not because physics required it but because nobody could see them in real time.
The consequence was not just inefficiency. When MH370 disappeared in March 2014, the absence of surveillance over the southern Indian Ocean became a global news story. The political pressure that followed accelerated investment in space-based ADS-B by several years. Aireon's system, declared operational in 2019, was the direct beneficiary.
What the satellite actually receives, and where it gets complicated
ADS-B Mode S Extended Squitter transmits on 1090 MHz at 250 watts peak power. The signal encodes the aircraft's ICAO 24-bit address, GPS-derived position, altitude, velocity vector, and flight identity. Transmissions are unsolicited and occur roughly twice per second. A LEO satellite at 780 km altitude has a footprint large enough to hear thousands of aircraft simultaneously over high-density oceanic entry and exit points.
That density is the central technical problem. When two or more aircraft transmit at the same instant, their signals overlap at the receiver and the message is lost. This is called a message collision, and the probability rises with the square of the number of aircraft in view. Published analysis from the pre-Aireon era estimated collision rates above 50 percent over the North Atlantic peak traffic band during busy periods. Aireon addressed this partly through Iridium's phased-array antenna design, which provides some spatial discrimination, and partly through redundant reception across adjacent satellites. The published result is that position updates arrive approximately every 8 seconds per aircraft over oceanic airspace, which is sufficient for 15-nautical-mile separation standards.
Latency matters differently depending on the application. Air traffic control requires near-real-time feeds, typically under 1 second from reception to display, which Aireon delivers via its ground network. Analytics applications, such as route optimisation studies or emissions accounting, can tolerate latency of minutes to hours and can use aggregated data products from Spire or archived exactEarth data.
The equipage problem nobody advertises
Space-based ADS-B only tracks aircraft that are transmitting ADS-B Out. That is not all aircraft. ICAO mandated ADS-B Out equipage for aircraft operating in most controlled airspace above certain altitudes, but implementation timelines vary by region and exemptions are common for older airframes. In 2023, ICAO estimated global equipage rates for commercial aviation above 90 percent on major international routes, but that figure drops sharply for general aviation, military traffic, and operations in states with weaker regulatory enforcement.
An aircraft without ADS-B Out is invisible to space-based receivers just as it is invisible to ground networks. This is not a failure of the satellite system; it is a limit of the underlying protocol. Surveillance of non-equipped aircraft requires different methods entirely, such as multilateration from ground networks or SAR-based detection of vessel-like targets, neither of which is covered here.
Oceanic route efficiency and the measurable gains
Before Aireon, North Atlantic Track System separation minima were set conservatively to account for positional uncertainty. With real-time surveillance, NAT operators began trialling reduced separation standards. ICAO and NATS published trial results showing that 14-nautical-mile lateral separation became achievable with space-based ADS-B, compared to the previous 23 or 30 nautical miles depending on the route. Tighter separation means more aircraft can use the optimal wind-avoiding tracks simultaneously, reducing fuel burn per flight.
Fuel savings on the North Atlantic alone have been cited by Aireon in published materials as running to millions of kilograms annually across the operator base. Those figures come from Aireon's own reporting and should be treated as indicative rather than independently audited. What is independently verifiable is that the separation standard changed, and that change has a direct operational cost consequence that airlines can calculate from their own fuel logs.
What analytics can be built on this data
The raw value of space-based ADS-B is surveillance continuity. The analytical value comes from what you do with a complete, timestamped record of aircraft positions globally. Route adherence monitoring compares filed flight plans against actual tracks to detect deviations, which is relevant for both safety investigations and airspace billing. Emissions accounting uses fuel-burn models applied to actual flown distances and altitudes, producing more accurate carbon estimates than schedule-based proxies.
Traffic pattern analysis over contested or sensitive airspace is a legitimate government use case. If military or state aircraft are operating with ADS-B active, their movements are publicly visible in the raw data. Many do not transmit, but the gap itself is informative when correlated with other intelligence sources. Satellize works with government clients on exactly this kind of layered analysis, combining open-protocol feeds with other data streams to characterise airspace activity. The methodology is the same one underlying the Overhead daily analysis column.
Historical archive depth varies by provider. Spire and exactEarth maintain multi-year archives. Aireon's data is primarily sold as a real-time surveillance service to air navigation service providers, with historical access governed by individual contracts. For open-source analytics, aggregated ADS-B data from ground networks such as OpenSky Network supplements space-based feeds over land, though the oceanic gap remains a space-only domain.
Honest limits before you commit to a specification
Space-based ADS-B is not a surveillance system for non-cooperative targets. It cannot detect aircraft that choose not to transmit, and it cannot resolve the identity ambiguity that arises when an ICAO address is spoofed or reused. Message collision rates, though managed by Aireon's architecture, still degrade over the highest-density corridors during peak hours. The 8-second update rate is an average; individual update intervals can be longer.
Polar coverage from Iridium NEXT is genuine, which distinguishes it from sun-synchronous CubeSat constellations that have coverage gaps at high latitudes depending on orbital geometry. For applications requiring continuous surveillance rather than periodic sampling, Aireon remains the only system with a published, contractually backed service level. CubeSat-based providers are appropriate for analytics workloads where occasional gaps are acceptable.
Typical figures
| Signal frequency | 1090 MHz (Mode S Extended Squitter) |
| Transmit power (aircraft) | 250 W peak (high-power installations); 70 W for low-power |
| Position update rate (Aireon, oceanic) | Approximately every 8 seconds per aircraft (published by Aireon) |
| Surveillance availability (NAT, published) | 99.9% (Aireon published figure for North Atlantic Track System) |
| Orbital altitude (Iridium NEXT) | ~780 km LEO |
| Constellation size (Aireon) | 66 operational satellites (hosted payload on Iridium NEXT) |
| Latency to ATC display (Aireon) | Under 1 second (real-time surveillance service) |
| Latency to analytics feed (Spire/exactEarth) | Typically 2 to 10 minutes for aggregated products |
| Coverage | Global including polar regions |
| Minimum detectable target | Any ADS-B Out-equipped aircraft transmitting on 1090 MHz; non-equipped aircraft are not detectable |
Analytics Satellize can run
| Oceanic route adherence report | Comparison of decoded ADS-B track against filed ICAO flight plan waypoints; deviation flagged by distance threshold | Per-flight PDF report or batch CSV for fleet operators; configurable deviation threshold |
| Actual-flown emissions estimate | BADA or equivalent fuel-burn model applied to space-derived altitude and ground-speed profile over full oceanic segment | Flight-level CO₂ and NOₓ estimates in tonne-CO₂-equivalent; monthly aggregate report |
| Airspace activity characterisation | Density mapping of ADS-B tracks by ICAO address class, operator, and time-of-day over defined airspace polygon | GIS layer (GeoJSON or shapefile) of traffic density; time-series chart of movements per hour |
| Anomalous track alert | Statistical deviation from historical route envelope for a given city-pair; flags altitude, speed, or heading outliers | Near-real-time alert feed (JSON webhook) with aircraft ICAO address, position, and deviation magnitude |
| Historical traffic baseline | Aggregation of multi-year archived ADS-B positions from exactEarth or Spire over defined region or route | Monthly traffic volume dataset; route-level percentile envelopes for altitude and speed |
| Equipage gap assessment | Cross-reference of ADS-B-visible traffic against schedule data to estimate proportion of flights not transmitting in a given region | Regional equipage rate estimate with confidence interval; briefing note for regulatory or procurement use |
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.