UAV

A UAV is an Unmanned Aerial Vehicle. In Season 6, it was used by Dmitri Gredenko and Abu Fayed to detonate a suitcase nuke over San Francisco. In Season 8 it was used by CTU New York for better surveillance.

Day 6
In Day 6, the suitcase nukes were used by a terrorist cell led by Abu Fayed. They acquired the suitcase nukes, codenamed "visitors", from BXG Technologies. BXJ, led by Graem Bauer and Phillip Bauer, Jack's brother and father, respectively. They detonated one nuke in Valencia, just as the field team was about to retrieve it. They were planning to detonate one of the other suitcase nukes on a UAV, but Jack took over the drone and landed it safely, but in the process exposing some of the nuclear material and turning it into a dirty bomb.

Day 8
In Day 8, CTU New York used drones (UAVs) under the control of drone pilot Arlo Glass, as surveillance. It was also revealed that they had rockets and guns on board.