"On 4 November 2002, Ali Qaed Sinan al-Harthi, a suspected al-Qaida operative, who is believed to have planned the Cole attack, was killed by the CIA using an AGM-114 Hellfire missile launched from an MQ-1 Predator unmanned [sic] drone."
All drones are pilotless (or "unmanned"), that's the essential meaning of drone.
drone* A pilotless airplane remote-contolled by radio signals, as from another airplane; also, a vessel remote-controlled by radio. (Webster's New International Dictionary; Second Edition, Unabridged; G. & C. Merriam Company, 1960.) * Additional definition; addenda.