The increasing congestion of commercial airspaces necessitated more efficient air traffic control (ATC) methods. The Automatic Dependent Surveillance-Broadcast (ADS-B) protocol is at the heart of the next-generation of ATC systems and is currently being rolled out in most countries. With ADSB, an aircraft determines its own position by using global navigation satellite systems and broadcasts it periodically over the 1090-MHz radio frequency to ground stations or other aircraft in proximity. This approach increases the accuracy of aircraft localization and enables lower separation requirements and improved situational awareness for pilots and controllers. At the same time, it is supposed to significantly reduce the costs of air traffic surveillance compared with former independent surveillance radar systems .
However, although ADS-B offers clear advantages going forward, there are many facets of the technology that need further evaluation to ensure a quick and safe adoption. Various concerns with the ADS-B protocol such as security vulnerabilities , wireless channel capacity limits , and data quality  have emerged over the past few years, requiring thorough investigation. This highlight presents an example of such research. Using a large-scale sensor network, we analyze differences in the implementations of the existing real-world ADS-B transponder equipage.
We find that not all implementations adhere to the existing standards and suggest potential exploitation of such differences, in particular, with regard to intrusion detection. Finally, we discuss the privacy implications of aircraft ¡°fingerprints¡± based on link or physical layer features.