Although the Federal Aviation Administration (FAA) can’t yet definitively answer those questions, studies by a consortium of leading universities through the Alliance for System Safety of UAS through Research Excellence (ASSURE), have begun to better understanding the risks associated with flying small unmanned aircraft – or drones –over people and things on the ground.
The ASSURE research team, led by The University of Alabama in Huntsville, began its research in September 2015, and included, the University of Kansas, Mississippi State University, and Embry-Riddle Aeronautical University. The research will help the FAA shape future follow-on research to set guidelines for UAS operations over people and possibly influence design specifications that reduce risk to people and property.
“The results of this work are critical to the successful commercial operations of flying unmanned aircraft over people and beyond the pilot’s visual line of sight,” said Mississippi State University’s, Marty Rogers, director of ASSURE.
Today at 3:00 p.m. EDT, at the FAA Federal Headquarters in Washington, D.C., the FAA along with ASSURE members, announced their findings in The UAS Ground Collision Severity Evaluation Final Report.
The report identified three dominant injury types applicable to small drones:
- Blunt force trauma – the most significant contributor to fatalities
- Lacerations – blade guards required for flight over people
- Penetration injuries – difficult to apply consistently as a standard
“The research team reviewed over 300 publications from the automotive industry, consumer battery market, toy standards and other fields to inform their research using the most modern research techniques,” said David Arterburn, director, Rotorcraft Systems Engineering and Stimulation Center at the University of Alabama in Huntsville and principal investigator for the study.
“From these, we were able to identify blunt force trauma, penetration injuries and lacerations as the most significant threats to people on the ground.”
The research also identified hazardous drone features, like unprotected rotor blades, and mitigations to reduce the severity of injury like rotor blade guards.
The research showed multi-rotor drones fall more slowly, due to aerodynamic drag, and cause less damage than the same mass of metal or wood. Drones also deform and flex more than wood and metal debris, imparting lesser amounts of energy and therefore less damage. The report also highlights that the lithium batteries that power many small drones need a unique standard to ensure safety.
Additionally, the report defines the characteristics of different unmanned vehicles and provides a detailed evaluation of payload characteristics, minimum weight and speed thresholds (i.e. too small to regulate), credible scenarios for evaluation, injury mechanisms defined as kinetic energy/energy density thresholds, blade energy thresholds, and mitigating characteristics of design.
Finally, the team conducted crash tests, dynamic modeling, and analyses related to kinetic energy, energy transfer, and crash dynamics.
When the studies were complete, personnel from NASA, the Department of Defense, FAA chief scientists, and other subject matter experts conducted a strenuous peer review of the findings.
The second phase of ASSURE’s research is set to begin in June 2017, and will verify the findings of this study, as well as develop tests manufacturers can use to certify their UAS for flights over people. Later this summer, the results of another study examining UAS collisions with aircraft will be released.
ASSURE partners represents 23 of the world’s top research institutions and more than 100 leading industry and government partners. (Learn more at ASSUREuas.org.) ASSURE membership includes representation in 13 states, 9 countries, and over 200 locations and core to 3 UAS test sites.