How flight trackers became the sleeper hit of the summer

Last Tuesday, viewers set new records on Flightradar24, one of the largest flight tracker websites in the world, as they watched the seven-hour flight of Nancy Pelosi from Kuala Lumpur to Taipei. The trip, shrouded in secrecy until its final moments, grabbed international attention after China made military threats in the weeks leading up to the visit, and then launched livefire exercises once she had landed.

Ian Petchenik, the head of communications for Flightradar24, said the site had seen “unprecedented sustained interest” over Pelosi’s flight, and at its peak, a record 708,000 people were simultaneously watching the little red icon representing the House speaker’s Boeing C-40C as it looped around the Philippines to bypass Chinese bases in the South China Sea, then soared across the Luzon Strait and arced across Taiwan’s mountain ranges before touching down in Taipei. In total, 2.92 million people tuned in to watch some portion of her flight.

Flightradar24 has had some other big moments of late: roughly 550,000 viewers tracking the flight of the Russian opposition leader Alexei Navalny as he returned to Moscow in 2021 to face imprisonment. Thousands more tracked a US air force Global Hawk travelling around Ukraine during the Russian invasion. Viewers also followed the chaotic evacuation from Afghanistan.

The appeal is simple, Petchenik said: “You get to participate in history in real time. If the newspaper is the first draft of history, then this is the pre-write.” Flight tracker data has virtually no lag, providing a raw sense of immediacy.

It’s not just global news events that spark upticks in site traffic. As transfer deadline day approaches, it becomes an essential tool for sports fans. “We see the most interest during the European football transfer window,” Petchenik said. “The teams have very dedicated fanbases. They will figure out what flight their favourite player is on, and they will follow that flight.”

Flight trackers rely on a new openstandard surveillance technology called automatic dependent surveillancebroadcast (ADS-B), which allows planes to transmit their locations and other information to anyone with a receiver.

Anyone can set up an ADS-B receiver using inexpensive kits. That’s allowed Flightradar24 to go from a couple of receivers in Sweden, when the site was founded in 2007, to a huge network with more than 30,000 receivers around the world, many of them run by volunteers. Flightradar24 also crossreferences its ground-based receivers with data from other sources, including satellites and data from the Federal Aviation Administration (FAA) in the US.

Subscribing to the government data comes with a catch: trackers must agree to abide by FAA rules that let aircraft owners request their information be removed from public websites. That means Flightradar24 displays some flights anonymously.

That’s where a popular uncensored flight tracker comes in: ADS-B Exchange. The website was founded in 2016 by Dan Streufert, an IT professional who describes the site’s policy: “We don’t block anything.” That’s possible in part because the site doesn’t subscribe to the FAA feed. Instead, it relies on data funnelled from a network of about 9,000 ADS-B receivers around the world run by volunteers.

Streufert’s network allows users to observe flights that powerful people want to be kept secret. Once, Streufert received a letter from a European lawyer who demanded ADS-B Exchange stop tracking his client’s flights. After looking up the flight data, Streufert realised: “The guy used to work for Gaddafi. He’s been accused of war crimes and killing people and yada yada. I guess somebody had used our data to figure out that he was moving gold from Venezuela to Libya on his private jet, and he wasn’t too happy about that being exposed.”

ADS-B Exchange’s approach to open data has also allowed citizen journalists to reveal the habits of America’s rich and famous. This year, a 19-yearold programmer named Jack Sweeney created a bot that tweeted out the flight paths of Elon Musk.

ADS-B Exchange’s data made headlines this summer when an environmental nonprofit used it to estimate the carbon emissions produced by stars including Drake, Kylie Jenner, Travis Scott and Taylor Swift – who has responded that her jet is “loaned frequently to other individuals”.

Steufert says official agencies frequently use ADS-B Exchange’s data, whose grassroots network may pick up movements that official systems don’t.

Steufert says sites like his are doing nothing wrong. “We don’t interpret the data – we leave that to journalists, media, researchers, whoever, to interpret what that might mean.”