A U.S. Air Force drone the size of a small airliner crashed in a remote section of California near Mt. Whitney.

Edwards Air Force Base said in a statement that the RQ-4 Global Hawk, an unmanned surveillance aircraft, was making a routine trip Wednesday afternoon from Edwards to its usual home at Beale Air Force Base when it crashed for unknown reasons.

The Inyo County Sheriff’s Department said the crash caused a small wildfire that was quickly under control.

The aircraft with a 130-foot wingspan is designed to fly at high altitudes for long distances. It’s slowly replacing the manned U-2 spy planes used for decades by the Air Force.

The cause of the crash is under investigation.

(AP)