The U.S. Marshals Service is using special planes to collect cellphone data from the sky in order to track down fugitives on the run. That's not the plot of the next Mission: Impossible movie - it's happening in real life. But, they don't just gather data from the fugitive's cellphone. In fact, every cellphone in the area is intercepted.
Marshals outfit Cessna airplanes with a special device that can track down a user's cellphone. If they suspect the criminal is in a general area, they can fly the plane overhead to try and track the person down. The agency is currently flying these planes out of at least five different airports around the country.
... [T]he planes are equipped with two-foot-square devices — sometimes called “dirtboxes” — that mimic cell towers and trick cellphones into reporting their unique registration information and general location.
While the technology has undoubtedly helped law enforcement officers track down criminals, it's also responsible for the invasion of many people's privacy by the government.