标题: A Website That Tracks Airliners in Real Time [打印本页] 作者: choi 时间: 8-27-2015 17:07 标题: A Website That Tracks Airliners in Real Time (1) Scott McCartney, The Facebook of Aviation; How Flightradar24, a Swedish tracking service, made itself essential by keeping tabs on flights in real time. Wall Street Journal, Aug 27, 2015 http://www.wsj.com/articles/the- ... y-flight-is-1440610
(“Want to follow your spouse’s arrival time on a flight from Dubai, or figure out what just flew over your house? Flightradar24 can track it in real-time”)
"Flightradar24 combines data from several data sources including ADS-B, MLAT and FAA. The ADS-B, MLAT and FAA data is aggregated together with schedule and flight status data from airlines and airports to create a unique flight tracking experience
"The primary technology that Flightradar24 use to receive flight information is called automatic dependent surveillance-broadcast (ADS-B). The ADS-B technology itself is best explained by the image to the right.
1. Aircraft gets its location from a GPS navigation source (satellite)
2. The ADS-B transponder on aircraft transmits signal containing the location (and much more)
"ADS-B is a relatively new technology under development, which means that today it's rarely used by Air Traffic Control (ATC). Our estimations show that roughly 70% of all commercial passenger aircraft (75% in Europe, 55% in the US) are equipped with an ADS-B transponder. For general aviation this number is probably below 20%.
"Flightradar24 has a network of more than 7,000 ADS-B receivers around the world * * * Due to the high frequency used (1090 MHz) the coverage from each receiver is limited to about 250-450 km (150-250 miles) in all directions depending on location. * * * The distance limit makes it very difficult to get ADS-B coverage over oceans.