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Unmanned Aerospace System Tipping Point

During the cold war era, reconnaissance missions were left to the U-2, and SR-71 amongst others.  These missions required endurance stretching the human pilot to their limits.  Unmanned aircraft development increased.  The technology at the time to remotely fly and gather the information was problematic with communication systems and sensors that were inadequate and often failed. 

UAV accidents can be classified to the categories of human factors, maintenance, aircraft, and unknown.  Human factors can be classified to more specific factors such as issue with alerts/alarms, display design, procedural error, skill based error, or other (Williams, 2004).  In the accident report data collected  in 2004, the percentage of human factors varies across different aircraft from 21% - 68%.  For most unmanned aircraft, electromechanical failure was a greater causal factor than human error.

The Navy’s RQ-2 Pioneer requires an external pilot for takeoff and landing before operating autonomously, unlike a more sophisticated UAV such as the Global Hawk.  Human factors accounted for 28% of accident causal factors. Of the RQ-2’s 239 accidents, 156 are aircraft related.  There was 68 human factors related accidents; 13% of were due to aircrew coordination, 68% from landing error, 10% from take-off error, and 9% for weather.  This data suggests there is much room for improvement for this UAV’s landing procedures whether related to the landing design, or lack of pilot training.

The Predator has different accident causal factors than the older Pioneer.  Also flown by a ground control station (GCS) by joystick and rudder pedals, human factors accounted for 67% of Predator accidents (up to 2004), with procedural error making up 75%.  An example of a procedural error involved and “handoff” of the aircraft from one crew to the next.  During the handoff, the crew did not comply with checklist steps in the proper order which resulted in the shutdown of the engines and stability augmentation system.  The aircraft entered an un-commanded dive and crashed.  I will take a wild guess and assume shortly after this incident, the combination of steps the pilots took should cause alarm to suggest that procedure should not happen. Pressing UAV flight to mandate certification of pilots through training and standardization of Human Machine Interface shall lower the human related factors for UAV incidents. 

Concluded from the breakdown of UAV accidents of some the major UAV platforms in this discussion, human factors and aircraft factors such as electromechanical reliability have in the past been principle causal factors.  Design of some user interfaces in the past were not based on aviation display concepts, mainly because the developers of those interfaces are not aircraft manufacturers (Williams, 2004).  In the traditional sense of the word, unmanned aircraft are not “flown,” they are “commanded.”  This highlights the criticality of human factors regarding pilot qualification and GCS interfaces.

References

Williams, K. W., & FEDERAL AVIATION ADMINISTRATION OKLAHOMA CITY OK CIVIL AEROMEDICAL INST. (2004). A summary of unmanned aircraft Accident/Incident data: Human factors implications

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