The FBI has filled the skies of America's cities with covert aircraft, crisscrossing overhead, bristling with sensors and cloaked in mystery, from the shell companies that own them to the obfuscated tail-numbers they sport.
The FBI won't talk about the capabilities or uses of their planes, but we can make some good guesses at their capabilities, thanks to the NYPD. The nation's largest police force did a lot of ill-advised bragging about its $10M spy helicopter, and since then, there's been a steady leak of good technical detail of what a state-of-the-art spy aircraft is likely doing when it passes overhead.
In addition to revealing the shell ownership, however, the FAA documents for the NYPD helicopter proved interesting for another reason. They provided a detailed list of all the components and modifications the Bell helicopter underwent to meet the NYPD's surveillance needs.
Spy equipment added to the NYPD helicopter in 2003 includes a WESCAM MX-15 Video Imaging System, also described as a Thermal Imager, and a WESCAM SkyPod B Airborne Microwave Transmission System. The latter includes a GPS receiver that allows the camera to zoom in on specified locations.
Additionally, there is a Comant CI 405 GPS antenna installed on the cockpit roof, a Chelton 931-8 Direction Finding system and a Datong Tracking System "for tracking targeted electronic beacons." The latter presumably is for monitoring GPS trackers that law enforcement agencies place surreptitiously on vehicles. (See the documents below for more details about the components installed on the aircraft.)
What an NYPD Spy Copter Reveals About the FBI's Spy Planes [Kim Zetter/Wired]
(Image: New York City Police Bell 412EP, Ad Meskens, CC-BY-SA)