(CNN) — On average, more than 200,000 flights take off and land around the world. This includes commercial, cargo and charter aircraft – which make up about half of the total – as well as business jets, private planes, helicopters, air ambulances, government and military aircraft, drones, hot air balloons and gliders.
Most of them are equipped with a transponder, a device that communicates the aircraft’s position and other flight data to air traffic control, and this signal can be picked up with inexpensive receivers based on a technology called ADS-B, for Automatic Dependent Surveillance-Broadcast. That’s what flight tracking websites do in a nutshell, providing users with a real-time snapshot of everything in the sky (with a few exceptions).
An ADS-B receiver manufactured by Flightradar24.
Courtesy of Flightradar24
The plane, a military version of the Boeing 737 dubbed C-40, flew from Kuala Lumpur in Malaysia before embarking on a circuitous route to Taiwan to avoid encounters with the Chinese military, adding hours of flight. It didn’t immediately make the final destination obvious, sparking conversations online as the plane slowly veered north toward the island. As a result, it was the most watched flight ever on Flightradar24, with 2.92 million people following at least part of the seven-hour journey.
The website, part of a group of popular flight tracking services along with FlightAware and Plane Finder, was founded in Sweden in 2006 “completely by accident”, says FlightRadar24 communications director Ian Petchenik, as a means of directing traffic to a flight. price comparison service.
Prior to Pelosi’s flight, the most-watched flight record on Flightradar24 belonged to Russian opposition leader Alexei Navalny’s return trip to Russia, where he was to be imprisoned. The January 2021 flight was watched by 550,000 people, breaking an earlier record set in April 2020, when nearly 200,000 users watched a Boeing 777 draw the crescent and star symbols of the Turkish national flag into the sky above Ankara, to celebrate Turkey’s 100th anniversary. sovereignty.
Before that, in September 2017, thousands saw a brave Delta Boeing 737 fly straight into Hurricane Irma to land in Puerto Rico and take off 40 minutes later for JFK by carefully positioning themselves in the spaces between the arms of the ‘hurricane.
Outside of big events, however, the number of people tracking flights keeps growing: “You see a lot of people using the site to track a loved one, track their own flight, or find the inbound flight they’re heading to. lead”. be later that day, to make sure the plane arrives,” says Petchenik.
“Another use case is for people who are very interested in aviation or really like to track certain types of planes. They can also go to the airport, open the app and see what’s going on. Then you have people who are professionally invested in the aviation industry, because they own a plane and they lease it, or because they have a fleet of planes and they “they want to keep an eye on them. Lastly, there are people who are professionally invested in having a lot of flight data. airlines, airports, aircraft manufacturers who use large data sets to obtain industry information.”
How data is collected
To collect the data, Flightradar built its own network of ADS-B receivers, which they say is now the largest in the world at around 34,000 units, covering even remote areas like Antarctica.
Flightradar24 has receivers all over the world, including remote locations like Antarctica.
Courtesy of Flightradar24
About a quarter of the receivers were built by Flightradar24 itself, but the majority are assembled by enthusiasts who provide the data on a voluntary basis. Because building a receiver is relatively cheap – the components cost around $100 in total – many have signed up since Flightradar24 began opening its network to the public in 2009.
A dense network of receivers is essential for tracking flights on a global scale, but there is an obvious problem with the oceans, where the network becomes sparse. So how do you get open water coverage?
“By finding islands wherever we can and making sure we have receivers there,” says Petchenik. “But more recently, we have moved to satellite-based ADS-B receivers, to be able to better track aircraft over the ocean. However, the most predominant source of data remains our own terrestrial network.”
Having such a large amount of granular and localized data can be useful for gaining early insight into emergencies and accidents: “We store everything that happens on our servers and, if necessary, we can go back to a specific receiver and extract the raw data. It’s usually done only if there’s been an accident or if we have a request from an air navigation service provider or an accident investigation branch,” says Petchenik.
However, not all data is available for every aircraft, as it depends on the type of transponders and receivers involved.
Aircraft owners or operators may also choose to prevent their data from being publicly displayed, most often for military, government or private aircraft. For example, they can enroll in a program such as LADD, for “Limiting Aircraft Data Displayed,” which is maintained by the Federal Aviation Administration: “We respect that list,” says Petchenik.
“This allows operators to display their data differently, anonymously or in some cases not display it at all. Of the total number of aircraft we track daily, around 3% have some type of regulation data display.”
Top image: A Boeing C-40C carrying United States House Speaker Nancy Pelosi takes off from Taipei Songshan on August 3, 2022, a day after SPAR19 became Flightradar24’s most tracked flight.