Hundreds of thousands of people used flight-tracking websites to follow the path of House Speaker Nancy Pelosi's historic flight into Taiwan on Tuesday (Aug. 2).
The real-time track of Pelosi's flight was made possible by a system known as Automatic Dependent Surveillance–Broadcast, or ADS-B, which uses precise tracking enabled by Global Positioning System satellites to provide accurate situational awareness to air traffic controllers.
At one point when Pelosi's flight was beginning its descent into Taiwan, popular flight-tracking website FlightRadar24 (opens in new tab) (FR24) showed over 345,000 people watching the path of SPAR19, the call sign given to the U.S. Air Force Boeing C-40C transport aircraft on which she flew.
Many users were unable to access the site at the time due to what FR24 called "unprecedented sustained tracking interest," according to a statement released on Twitter (opens in new tab).
Prior to the introduction of satellite-based ADS-B air traffic monitoring by the European Space Agency (ESA) in 2013 (opens in new tab), controllers and aviators relied on radar and short-range radio navigational aids (opens in new tab). These ground-based systems do not offer the precision of satellite-based systems, and can be limited in range or blocked by terrain.
According to the U.S. Federal Aviation Administration (FAA), the more precise location data facilitated by satellite-based navigation systems such as GPS enables more efficient and safer flights (opens in new tab).
"The improved accuracy, integrity and reliability of satellite signals over radar means controllers will be able to safely reduce the minimum separation distance between aircraft and increase capacity in the nation's skies," according to an FAA statement (opens in new tab).
"ADS-B also provides greater coverage since ground stations are so much easier to place than radar," the statement adds. "Remote areas without radar coverage, like the Gulf of Mexico and much of Alaska, now have surveillance with ADS-B."
Pelosi departed Taiwan on Wednesday (Aug. 3) after meeting with the nation's president and other high-ranking officials. The house speaker's outgoing flight did not draw nearly as much attention as her arrival, during which Chinese military aircraft flew aggressively close (opens in new tab) to Taiwanese airspace.