Set to autopilot

"The bomber disappeared from the radar screen just before midnight. Days later, 12 of the 17 men onboard were found alive. The plane, set to autopilot by the crew before they parachuted out of the aircraft, crashed into the snow-covered mountains of northern British Columbia." (The Guardian.)

Is "set" a past participle and "to autopilot" an infinitive in a catenative construction or is "autopilot" a noun, an uncountable one in the above paragraph?