US explained why a US Air Force Global Hawk drone crashed and destroyed itself last year.  It is stated that the crash is as a consequence of the aircraft’s “erroneous” data.

Incident investigation report published by the military this week claims that the drone, “having failed to detect the erroneous nature of LNA's navigational data, sent control inputs to correct the false roll data.” According to report, “this included keeping a full throttle, even while the [RQ-4] was in an unusual nose low attitude… the [RQ-4] regained roll control, but airspeed continued to increase.”

It appears that user error in flipping off the aircraft's navigators was a deeper cause of the incident. Investigator Col. Jeremy Thiel opined in the report, “I also find by a preponderance of evidence that disabling the two Kearfott KN-4074E navigators after takeoff substantially contributed to the mishap.”

The RQ-4 employs a quad-redundant Inertial Navigation System/Global Positioning System (INS/GPS) configuration. The system utilizes two different INS/GPS systems for greater redundancy. The system consists of two LN-251 units and two Kearfott KN-4074E INS/GPS Units.

Those Kearfott navigators were switched off by the craft's operators shortly after the drone lifted off, according to an investigation into the event. It's not clear why the navigators were switched off.

A Northrop Grumman contractor in Palmdale, California, launched the $79 million aircraft before it went into a self-pilot mode, in June.