In addition to carrying two Hellfire laser-guided missiles, the Predator carries infrared sensors, color and black and white cameras, and can stream video for flights up to 24 hours, according to the Air Force. The Global Hawk has a similar range and includes special motion-detecting radar systems.
Still, neither of these drones can penetrate forest canopies or inside tents. That means their best chance may be to catch movement of trucks or groups of people in the open.
Once the schoolgirls are spotted, an international rescue force might be able to use a lower-flying drone such as the Raven, Wasp or Puma to pinpoint exactly who they are and what they are doing.
“They can tell the difference between a shovel and a machine gun,” said Steve Gitlin, vice president for communications at Aerovironment, which has sold more than 9,500 such unmanned aircraft to the U.S. military. These small, 3- to 13-pound drones can be assembled and launched by troops on the ground with a quick toss, according to Gitlin, and fly only a few hundred feet above ground. They also have special infrared radar that allow them to observe people at night. “It draws a red box around them, and makes it easier to look for moving people,” he said.
The Nigerian government purchased several Israeli-made drones in 2006 to hunt rebels, but officials never ordered spare parts of learned how to use the aircraft, according to Israel’s Haaretz newspaper.
"To the best of our knowledge, these systems aren't operational," Tsur Dvir, marketing officer for Aeronautics Defense Systems, a firm based south of Tel Aviv that supplied Nigeria with Aerostar unmanned aerial vehicles, told Haaretz.
Absent any Nigerian drones or Nigerian troops, some local residents are fed up. They are reportedly forming vigilante groups to find the kidnapers armed with low-tech bows and arrows.