During Day 9, First Lieutenant Chris Tanner was flying a MQ-1 Predator from Lower Heyford Air Force Base, London, United Kingdom. His mission was to provide aerial reconnaissance to his superior Major Shepherd's U.S. military convoy in Kajaki Province, Afghanistan. However, after finished his mission, someone hacked his drone and armed one of the Hellfire missiles. Although Tanner tried to alert Shepherd by phone, the drone fired the missile and destroyed the armored vehicle. The attack succeeded and resulted two American and two British airmen were killed.
Later, Jack Bauer and Chloe O'Brian learned that a hacker named Derrick Yates had developed a defense override module that allowed him to take control of U.S. military drones, each of which carries six Hellfire missiles.