What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Flight-tracking apps do not locate distant aircraft with your phone’s GPS. They collect radio broadcasts sent by aircraft, receive them through ground and satellite networks, and combine the resulting tracks with flight and aircraft information. The map is an aggregated, near-current service view: coverage and timing vary, and it does not necessarily show every aircraft.
How a plane’s position reaches the app
- Onboard avionics determine the aircraft’s position. Aircraft can use satellite navigation such as GNSS to establish their position. With Automatic Dependent Surveillance–Broadcast (ADS-B) Out, the aircraft broadcasts its position and other information, including altitude and ground speed, about once per second. The FAA’s ADS-B overview contrasts that update rhythm with radar position sweeps every 5 to 12 seconds.
- Receivers pick up the transmission. ADS-B is a radio broadcast, not a signal sent to a tracking app by the passenger’s phone. Ground receivers need to be within reception range. Line of sight, aircraft altitude, terrain, transmitter power, and receiver sensitivity all affect whether a signal can be heard. In the United States, the relevant ADS-B frequencies include 978 MHz UAT and 1090 MHz extended squitter; see the FAA ADS-B FAQ and Aeronautical Information Manual.
- Networks send detections to tracking services. Providers collect signals from networks of receivers and may supplement them with satellite ADS-B, radar, multilateration (MLAT), or other feeds. The mix differs by provider and region.
- The service calculates or enriches the track. The service may estimate a position from signal timing, then associate the track with flight plans, schedules, aircraft records, or an identifier transmitted by the aircraft.
- The app displays the processed result. The moving map is the end of a chain of reception, calculation, matching, and display. “Real time” means near-current information, not an instantaneous, uninterrupted picture.
What ADS-B, MLAT, and satellite tracking contribute
ADS-B: the aircraft broadcasts its position
ADS-B stands for Automatic Dependent Surveillance–Broadcast. “Dependent” means the aircraft’s avionics derive the position from navigation sources; “broadcast” means the aircraft sends that information outward for receivers to hear. ADS-B Out broadcasts position and other data approximately once per second, according to the FAA.
As an Amazon Associate I earn from qualifying purchases.
ADS-B is not universal. Requirements depend on jurisdiction and airspace. The FAA describes ADS-B Out requirements for specified U.S. airspace under 14 CFR §91.225; this does not mean every aircraft worldwide must transmit ADS-B everywhere. The FAA Aeronautical Information Manual provides the U.S. equipment and frequency context.
MLAT: estimating a position from signal timing
Multilateration, or MLAT, can estimate an aircraft’s position from transponder signals that do not themselves contain ADS-B position. A service compares the time at which multiple receivers hear a signal; the differences in arrival time help calculate where it originated. Flightradar24 describes its method as using three or more receivers.
#1 Best Overall
- DUAL BAND: 1090 and 978 UAT receivers. Detect aircraft on both frequencies. Ground based receiver only.
- ACCESSORIES: includes unit, two antennas, micro usb cable, power adapter, SD card installed with unmodified PiAware 8.2 pre-loaded SD card.
- PLUG AND PLAY: just configure your WiFi network on the microSD card, plug in, and go!
- WIDE RANGE: detect aircraft up to 150 NM away with included high gain antennas from the ground.
MLAT depends on enough suitably placed receivers hearing the same transmission. Flightradar24 says its coverage commonly needs aircraft to be around 5,000–10,000 feet or higher in many locations, though the threshold varies. Its published performance figures are provider-reported, not a universal guarantee: it gives an optimal positional accuracy of 10–20 meters, a more typical stated range of 10–100 meters, and rare errors up to 1,000 meters. It also cautions that speed estimates can be wrong, particularly during turns. See Flightradar24’s MLAT explanation.
Satellite ADS-B and other feeds
Satellite receivers can hear ADS-B broadcasts over areas beyond the reach of a terrestrial receiver network. They extend reception, but do not guarantee uniform coverage over every ocean or remote region. Providers may also incorporate radar, UAT, FLARM and other glider-tracking feeds. For example, Flightradar24 describes using a combination of global receiver data, satellite ADS-B, radar in North America and Australia, MLAT, UAT, and FLARM. That is its account of its own service, not a description of every flight-tracking app.
Rank #2
- FlyCatcher is an extremely high-performance, dual-channel SDR for airplane tracking and positioning applications. It is designed to receive both ADS-B (1090 MHz) signals and UAT (978 MHz). Outperforms all existing low-cost ADS-B solutions!
- Designed in a Pi HAT form factor for seamless compatibility with Raspberry Pi, but is also compatible with other Windows, Linux, Android and Mac OS host devices
- FlyCatcher has a compact form factor, making it portable and easy to carry, whether used with a Pi or a different host device. Despite its small size, it delivers impressive performance, ensuring reliable and accurate data reception for all your aviation-related endeavors
- This device comes with 2 separate preamplifiers that have ultra-low noise levels. You can choose to bypass them either using an external switch or software GPIO0, which is especially convenient when in extremely close proximity to a transmitter
- Your purchase includes the FlyCatcher dual-SDR Pi HAT, standoffs and headers to facilitate connection with a Pi, and 2 USB cables for connectivity to your host device. Though FlyCatcher does not utilize the Raspberry Pi GPIO due to its inherent bus speed limitations, there is a passthrough so the header can be utilized for other projects or Pi HATs
Why a plane may not appear—or may disappear
- Radio reception is limited. A ground receiver may not hear an aircraft because of distance, terrain, line of sight, altitude, or receiver conditions.
- There may not be enough receivers for MLAT. If too few receivers detect the same transmission, a service may be unable to calculate or continue displaying an MLAT track. Flightradar24 says an aircraft can disappear from its map after descending below the level where three receivers can hear it.
- Aircraft equipment and provider feeds differ. Aircraft do not all transmit the same data, and services do not all have the same receivers, sources, or regional coverage.
- Processing and display take time. Position calculation and delivery to the app introduce latency. The FAA defines uncompensated latency as a delay between calculating an aircraft’s position and broadcasting it that avionics cannot correct by extrapolating the position.
- Flight identification may not match cleanly. A displayed flight number or aircraft identity can depend on matching transmitted identification with flight-plan, schedule, or aircraft records. The FAA notes that a mismatch between transmitted flight identification and a filed flight plan can impede correlation in its automation systems.
A gap or disappearance on one consumer map does not establish why a particular flight is absent, and it does not mean the aircraft has vanished from air traffic control surveillance. The actual cause depends on the aircraft, location, tracking method, and provider.
What the map can—and cannot—tell you
A public tracker is useful for following flights, but it is an aggregated service display with coverage gaps and processing delays. The FAA says ADS-B information received air-to-air and ground-to-air is for situational awareness; a consumer app should not be treated as an authoritative air traffic control display or a safety tool. The FAA ADS-B FAQ explains the system’s intended context.
Rank #3
- Wide Frequency Coverage: Supports 978Mhz-1090Mhz band, fully compatible with ADSB flight tracking and SDR signal reception projects
- High Gain Performance: 6dBi signal gain enhances reception sensitivity, helps capture stable signals for DIY radio experiments and hobby use
- Standard Interface: SMA male connector ensures easy connection with most SDR receivers, RTL-SDR devices and radio DIY equipment
- Compact Design: 7.74inch (19.66cm) length, lightweight and portable, convenient for desktop setup or outdoor temporary installation
- Durable Construction: Premium material resists daily wear and tear, designed for long-term use in tech DIY projects and hobby applications, package includes 2 x Kaunosta 1090Mhz ADSB Antenna
ADS-B ground stations can be placed more flexibly than radar and provide surveillance in some areas that previously lacked radar coverage, according to the FAA. That aviation-system benefit does not guarantee complete reception in a consumer app at every location.
What varies from one tracking service to another
There is no basis here for ranking providers by worldwide completeness or end-to-end latency. To understand what a particular map is showing, compare its coverage and data disclosures along these lines:
- Ground receiver and satellite coverage in the region you care about.
- Whether it uses ADS-B, MLAT, radar, UAT, glider feeds, or other sources there.
- How it identifies or labels estimated, MLAT, or delayed tracks.
- How it matches position data with flight status, schedules, and aircraft details.
Provider-reported scale figures are not measures of completeness. Flightradar24 says it has more than 50,000 receivers across seven continents and in space, and a database containing more than 1.5 million aircraft; these figures describe the company’s service and may change. They do not mean that every aircraft is visible at all times. See its service description.
Recommended Free Tools
Optional: receive ADS-B broadcasts yourself
For an educational project, a local ADS-B receiver can let you receive nearby aircraft broadcasts. Flightradar24’s receiver guide specifies a Raspberry Pi 3B+ or newer, a microSD card, a power supply, and an ADS-B USB receiver dongle with an antenna; it recommends a dongle based on RTL2832/R820T2. This setup is not needed to use a flight-tracking app, and reception range varies with altitude, terrain, transmitter power, and receiver sensitivity.
Quick Recap
Best Value
- Includes 1x RTL-SDR Blog brand R860 RTL2832U 1PPM TCXO HF Bias Tee SMA Dongle (V3) (Dongle Only)
- Several improvements over other brands including use of the R860 tuner, improved component tolerances, a 1 PPM temperature compensated oscillator (TCXO), SMA F connector, aluminum shielded case with thermal pad for passive cooling, and an activatable bias tee circuit.
- Can tune from 500 kHz to 1.7 GHz and has up to 3.2 MHz of instantaneous bandwidth (2.4 MHz stable). (HF reception below 24 MHz in direct sampling mode with reduced performance). Please note RTL-SDR dongles are RX only.
- Please follow the quickstart guide linked in the included the manual for installation of the drivers and free software. Please feel free to contact us via Amazon messaging for technical support - we're happy to help
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
