It's bad enough the government has been skulking around in cars and vans with a little device that can impersonate a cell phone tower and track you.

Now, in a move that should surprise no one, it's taking to the skies to expand its tracking reach, in a move that would also allow it to collect data on more people at once.

That's according to a new report from the Wall Street Journal indicating that the government has been using Cessna planes outfitted with special phone surveillance equipment to track suspects. But the surveillance system is designed to pick up the phone signals of anyone within range. The range of the equipment is currently unknown, but it means that data on potentially tens of thousands of phones could be collected during a single flight.

The airplane-based system is a 2-foot-square box called the Dirtbox—after the Boeing subsidiary that manufactures it (the Boeing division is known as DRT, for Digital Receiver Technology Inc). It appears to be the same or similar to so-called IMSI catchers or stingrays that law enforcement, the military, and intelligence agencies have been using for more than a decade.

The secretive stingray technology allows law enforcement agents to spoof a legitimate cell tower in order to trick nearby mobile phones and other wireless communication devices like air cards into connecting to the stingray instead of a phone carrier’s legitimate tower. When a device connects, stingrays can see and record its unique ID number as well as information that points to the device’s location.

Planes Are the Logical Next Step

Stingrays are often deployed by law enforcement from cars and vans. By driving the stingray around in a vehicle and gathering a wireless device’s signal strength from various locations in a neighborhood, authorities can pinpoint where the device is being used with much more precision than they can get through data obtained from a mobile network provider’s fixed tower location. The tools can pinpoint a phone's location down to an apartment building or complex. At that point agents can switch to a handheld device that operates in the same way but lets them move inside to determine the exact apartment or office location of the targeted phone.

One of the main problems with this surveillance method, however, is that the devices force every cell phone in a region to connect to them; so if a government stingray drives past your office, it will collect the signal of your phone as well as the government's target. That reach is magnified when the government casts its net from a plane.

Aerial surveillance is obviously much better than tracking via a van or car since vehicles can't easily maneuver through busy streets or in rural areas. A plane is going to move much faster over a wider region and collect many more phones than a ground station will. But this also means that the signal strength of the Dirtbox is probably greater than the ground-based stingrays—which likely means they pick up connections from many more phones unrelated to an investigation.

Authorities insist that only data related to a suspect is retained and used. The device determines which phone belongs to a suspect and then releases any other unrelated phones. But that's no comfort to civil liberties activists, since the government has attempted on numerous occasions to hide its use of stingrays from the courts and from defendants snagged by the equipment and may be concealing their use of the Dirtbox as well.

Who Uses the Dirtbox?

It's unclear how long aerial surveillance has been conducted in this manner. A 2008 document about stingray systems made by the Harris Corporation, and obtained by Public Intelligence, shows that six years ago the company was selling an airborne mounting kit for its cell phone surveillance systems at a cost of $9,000, indicating that it has been going for a long time already.

The Wall Street Journal indicates the Dirtbox systems are used by the U.S. Marshals Service, which operates Cessna aircraft from at least five metropolitan-area airports, the locations of which allow for a flying range that would cover cell phones used by most of the U.S. population. The systems are used for locating cellphones linked to individuals under investigation, including fugitives and drug dealers.

The U.S. Marshals Service, however, is known to loan out its stingray equipment to local police departments, as a recent case in Florida shows. So it very likely lends its Dirtbox service to multiple agencies around the country as well—possibly even to the U.S. Customs Border Control to detect and track smugglers and illegal border crossings.

It's unclear what authorization authorities are obtaining to use the Cessna Dirtbox. The Journal quotes an official who says that law enforcement obtains a court order to conduct the surveillance. But it's unclear how much the judges who approve such court orders are told about the nature of the tracking being done and the capabilities of the technology being used.

There have been cases in which law enforcement agencies either bypassed the courts and used stingrays without obtaining an order as well as cases in which they lied to or withheld crucial information from judges about their use of the technology in order to get a court order without a lot of questions being asked.