The US government is supposedly using Cessna aeroplanes to gather data from its citizens' mobile devices, according to The Wall Street Journal.
The planes are using two-foot square data gathering devices attached to Cessna airplanes that mimic phone towers and force the mobile devices to transmit back their location and unique identity data.
These 'dirtbox' devices collect information from all devices in the area, so even if the operation is only being used to track criminals, thousands of people are being tracked at the same time.
The Wall Street Journal's source said it has been used by the US Marshals Service since 2007, operating from five metropolitan areas around the country.
Although the report said the US Justice Department 'dumps' data it doesn't need, it's not clear how quickly this is done or if operatives are able to read the information before it's scrapped.
The US government's method of data collection is similar to that of Stingray, which is another IMSI (International Mobile Subscriber Identity) catcher that pretends to be a mobile cell tower. However, they can be purchased for around 2,000 or produced even more cheaply by novices.
Prof Alan Woodward told the BBC: "I'm not surprised to hear that it is going on. It's easily done. Doing it from the air is the obvious place to do it, but the question is under what legislation they are doing it and what are they doing with the data."
The US Justice Department would not comment on whether the information was true or not. However, the source told The Wall Street Journal the department had put a lot of work into trying to ensure the dirtboxes didn't interfere with emergency 911 calls.
