First drone passes Virginia Tech’s test for safe flights over people under FAA rule
In April 2021, the Federal Aviation Administration (FAA) published a long-awaited rule outlining requirements for drone flights over people. That December, the federal agency signed off on a means of compliance developed at Virginia Tech that could determine if an aircraft met those requirements — the first, and still only, set of test methods to demonstrate adherence to a regulation expected to significantly expand drone operations.
Now, for the first time, aircraft have passed.
The drones are three models in the eBee X series, lightweight foam aircraft manufactured by AgEagle. The approval means that anyone operating one of these drones in an applicable configuration can legally fly over people without having to seek permission for each individual operation through a complex waiver system — a radically streamlined process that will be a boon for AgEagle.
The milestone is a nod to the value of Virginia Tech’s testing, the product of a collaboration between the Virginia Tech Mid-Atlantic Aviation Partnership (MAAP), an FAA-designated drone test site, and injury biomechanics experts in the university’s College of Engineering.
It also marks the beginning of a broader shift in the way drone operations will be planned and conducted in the U.S.
“This is a major, major change in how things are done,” said Tombo Jones, the test site’s director. “The rule provided the first clear understanding of what’s required to safely operate over people. Our means of compliance provided the first pathway for utilizing the rule. This approval demonstrates that that pathway is viable.”
The fixed-wing drones in the eBee X series are commonly used for missions such as mapping, surveying, and inspections.
“We are confident that this will serve as a key driver in the growth of eBee utilization in the United States,” said Barrett Mooney, AgEagle’s chairman and CEO. “It will further improve the business applications made possible by our drone platform for a wide range of commercial enterprises which stand to benefit from adoption of drones in their businesses — particularly those in industries such as insurance for assessment of storm damage, telecommunications for network coverage mapping and energy for powerline and pipeline inspections, just to name a few.”
Under the waiver system, permission to fly over people was granted on a case-by-case basis and was generally limited to a narrow set of circumstances: A waiver would specify an aircraft, operator, flight location, and other parameters. Change any of these, and a new waiver was required. The system prioritized safety in an industry where technology was changing rapidly, but it made conducting new operations painstakingly slow and very expensive.
When the new rule went into effect in 2021, it replaced that complex process with a clear, universal standard that depended on a single parameter: Potential injury severity.
That reoriented research around the central question of what degree of injury a drone could potentially cause if it hit someone (an event, it’s worth noting, that is extremely unlikely in the first place).
One straightforward way to determine injury severity is to calculate how much kinetic energy the aircraft could theoretically transfer based on its mass and speed at impact. Most drones that are practical for commercial applications are too heavy, or flying too fast, to meet that simple standard. But in most cases, there’s a gap between how much kinetic energy a drone could potentially transfer and how much it actually will. That gap is where the opportunity lies.
When they hit something, most drones will bend, crack, fall apart, or deform in other ways. Those processes — many of them proactively engineered into the aircraft’s design — siphon off kinetic energy, softening the blow.
Pinpointing that actual kinetic energy transfer is the heart of the means of compliance MAAP developed in collaboration with the College of Engineering researchers, led by Associate Professor of biomedical engineering and mechanics Steve Rowson.
MAAP has built a national reputation for understanding risk in drone operations; Rowson’s team is equally renowned for realistic impact testing that yields quantitative measures of injury risk.
“We brought our expertise in conducting research on failure modes, and they brought their expertise in assessing injury risk,” said Robert Briggs, MAAP’s chief engineer, who led the development of the means of compliance. “We had worked together on waivers to operate over people, which were exceptions to the rule at the time — now we can utilize the talent and expertise that we built to comply with the new rule.”
The researchers begin by determining what circumstances would be most likely to lead to a significant impact for a particular aircraft. They design impact tests that replicate those conditions and compare the energy transferred by the drone to the amount transferred by a rigid block that has the same mass but won’t deform or break the way the drone will. They also conduct testing to ensure that the drone doesn’t have any exposed rotating parts capable of lacerating skin.
The FAA’s operations over people rule outlines four risk-based categories. When the team put the eBee X through the battery of impact tests, in a configuration with a mass of 1.42 kg, it fell below the threshold for Category 3. That allows it to be flown over people on a site with restricted access, or on an open-access site if it’s not loitering directly over people.
Identifying safe aircraft is the immediate objective of the testing under the means of compliance. But for the Virginia Tech team, the broader goal is understanding more about how to make aircraft safer, and how to test them effectively.
“The eBee X is a lightweight aircraft,” Briggs said. “Heavier aircraft will need different mechanisms to reduce injury risk. There’s always room to add to the test methods and always room to test new aircraft. The more we test, the more we’ll learn about what design characteristics work to decrease injury risk and which ones don’t.”
This victory for the eBee X is just the beginning. But, said Briggs, “having the first compliant aircraft in the U.S. for operations over people is a pretty good first step.”