Plenty of people have their reservations about the widespread adoption of drones, and rightly so with more and more of them buzzing around. But how real is the threat that they pose exactly? A study issued by the US Federal Aviation Administration (FAA) has sought to bring some figures into the discussion, finding, among other things, the chances of a head injury from a falling drone to be 0.03 percent.

The study kicked off in September 2015 and is being carried out by the Alliance for System Safety of UAS through Research Excellence (ASSURE). This collaboration includes researchers from the University of Alabama in Huntsville, the University of Kansas and Mississippi State University, and has set out to bring better understanding of the risks surrounding drones and the public.

"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 the University of Alabama in Huntsville's David Arterburn, 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."

As part of the study, the team conducted crash tests as a way of investigating kinetic energy, energy transfer and the dynamics of a collision between a falling drone and a human head. Their results were then peer reviewed by NASA, the Department of Defense and FAA scientists.

This involved comparing the impact velocity and chances of injury when struck by a drone (as judged by motor vehicle standards), compared to a piece of wood or steel of the same weight. The team found that a 2.7-lb drone (1.22 kg) landing on your head brought a 0.01 to 0.03 percent chance of head injury, compared to a 99 to 100 percent chance from both the wood and steel. Risk of neck injury was rated at 11 to 13 percent, compared to probabilities of around 60 to 70 with the other materials.

The research found that drones fall more slowly than wood or metal of the same mass due to the aerodynamic drag, and therefore cause less damage. What's more, a drone is more forgiving and will flex more on impact, therefore transferring less energy in the process.

These results seem pretty positive, as an increasing number of companies and startups incorporate drones into their business operations. But having seen drones fall out of the air ourselves, we still wouldn't like to be sat squarely underneath as one comes plummeting to the ground. In June this year, ASSURE will begin the second phase of its research. This will involve verifying the results of this initial study and developing tests that drone manufacturers can use to certify their aircraft for flights over people on the ground.

Source: ASSURE 1, 2 (PDF)

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