Whether the spy plane's mission was linked to intelligence-gathering related for the president's decision is unclear. The Navy's P-3 spy plane, a child of the Cold War, was first used for antisubmarine warfare. The Navy uses about 18 of the more sophisticated EP-3 planes to keep watch along the coastlines of various countries. Normally flown by a crew of 20, the plane can collect both radar and communications intelligence. The crew is able to listen to a wide range of frequencies, picking up information of just about any kind.
Linguists scan conversations looking for key words, defense specialists say.
In addition to watching military maneuvers, the spy planes are often used to plot the location of another country's radars and other facilities. The turbo-prop planes fly at 200 to 380 miles per hour, far slower than the shuttle from Boston to New York, specialists say. The spy planes typically fly at about maximum altitude of 30,000 feet and can stay aloft for more than 12 hours. Satellites just don't give you everything,'' said Barry Posen, a professor in the Massachusetts Institute of Technology's Security Studies Program.