It appears that the initial comments from drone groups and forums have missed some of the most significant parts of the new rules buried in the nearly 1,000 pages of combined documentation. As is typical, the devil is in the details.
I’m going to tackle the hidden issues in a series of posts since I’m afraid that tackling them all at once would be thousands of words.
The primary concerns I have from the rules surround Remote ID, propeller guards, flight over people, and night flight.
For this article, I’m going to focus on the flight over people and propeller guards.
Here is precisely what the final rule says about the category of aircraft that are impacted by this rule:
“The final rule establishes four new categories of small unmanned aircraft for routine operations over people: Category 1, Category 2, Category 3, and Category 4. The final rule also allows for routine operations over moving vehicles.
- Category 1 eligible small unmanned aircraft must weigh less than 0.55, including everything on board or otherwise attached, and contain no exposed rotating parts that would lacerate human skin. No FAA-accepted Means of Compliance (MOC) or Declaration of Compliance (DOC) required.
- Category 2 eligible small unmanned aircraft must not cause injury to a human being that is equivalent to or greater than the severity of injury caused by a transfer of 11 foot-pounds of kinetic energy upon impact from a rigid object, does not contain any exposed rotating parts that could lacerate human skin upon impact with a human being, and does not contain any safety defects. Requires FAA-accepted means of compliance and FAA-accepted declaration of compliance.
- Category 3 eligible small unmanned aircraft must not cause injury to a human being that is equivalent to or greater than the severity of injury caused by a transfer of 25 foot-pounds of kinetic energy upon impact from a rigid object, does not contain any exposed rotating parts that could lacerate human skin upon impact with a human being, and does not contain any safety defects. Requires FAA-accepted means of compliance and FAA-accepted declaration of compliance.
- Category 4 eligible small unmanned aircraft must have an airworthiness certificate issued under Part 21 of FAA regulations. Must be operated in accordance with the operating limitations specified in the approved Flight Manual or as otherwise specified by the Administrator. The operating limitations must not prohibit operations over human beings. Must have maintenance, preventive maintenance, alterations, or inspections performed in accordance with specific requirements in the final rule.”
Note: Category 2 is 11 a minimum of ft/lbs and Category 3 is 25 ft/lbs or more. You can find the exact wording in the new FAR Part 107.120 and 107.130 that have not been published yet but new wording is in the final rule documentation. The new regulations will become effective 45 days after the publishing of the final rule in the Federal Registerer.
I have been beating the drum for the past year about the need over airworthiness issues. There is no need to deal with that here.
Here is where the new rule’s critical part is and how it will impact nearly every drone flown for public safety and other uses. The key part of the rule that it appears most are missing is when it talks about the foot-pounds of the aircraft’s kinetic energy potential.
To understand how kinetic energy “impacts” your flight operations can be demonstrated by this accident report, I analyzed.
Determining Your Aircraft Category
A drone falling into this category could be any drone over .55 pounds. Measuring kinetic energy is a function of the gravitational influence and the weight of an object. So a small Mavic and large Matrice can both fit into the same category.
Aircraft in this category are those that have the potential to impact with at least 11 foot-pounds (ft-pounds) from a rigid object. A plain-language reading of this requirement seems to say that the determination for compliance is made by pushing an item from a height and takes no account for any lift generated by the aircraft. It makes sense since the concern is about the loss of and resulting impact. The impact number also does not use the calculation for potential energy, which would require heigh to be factored in.
So let’s look at real numbers.
DJI reports a Mavic 2 Enterprise zoom edition weighs 905 grams without any accessories.
To calculate the kinetic energy of an impact, we need to know the velocity created by gravitational force. This is a standard measurement of 9.8 meters per second on the earth’s surface.
A Mavic 2 Enterprise has a kinetic energy result of 32 ft-pounds of kinetic energy upon impact.
DJI reports a Matrice 300 with a single downward gimbal weighs 6.3 kilograms without any additional payload but with two TB60 batteries.
This aircraft has a kinetic energy measurement of 223 ft-lbs of impact force.
Where Does This Leave You?
The calculations show that both a Mavic and a Matrice would fall into a Category 3 UAS. These aircraft would not be able to operate over any open-air assembly of people.
The FAA states an open-air assembly is not a concert crowd it is something much smaller.
In this legal opinion, they say, “[u]nder Board precedent, a picnic area, if it is sufficiently populated can be an open air assembly of persons. So can a beach area.” The FAA legal interpretation refers to this NTSB document for further clarification.
If I had to give you a rough definition of an open-air assembly in a public safety context, I would suggest that you evaluate the situation not based on the total number of people but on how close the people are congregated.
For example, in one incident scene, I saw eight police vehicles and about ten officers. The situation drew a crowd of about 15 more citizens mulling about observing the incident. Given the NTSB and FAA statements, that would seem to be an open-air assembly in that general location.
A structure fire with multiple units on hand would be an open-air assembly in my opinion.
If you are not flying over an assembly of people, you would have to make sure your flight meets one of the two following conditions:
- The operation is within or over a closed- or restricted-access site and all human beings located within the closed- or restricted-access site must be on notice that a small unmanned aircraft may fly over them
- The small unmanned aircraft does not maintain sustained flight over any human being unless that human being is directly participating in the operation of the small unmanned aircraft; or located under a covered structure or inside a stationary vehicle that can provide reasonable protection from a falling small unmanned aircraft.
The FAA has previously stated that the only people who fall under the definition of “participating in the operation” are only the pilot and visual observer.
According to the final rule discussion, FAA says, “To be eligible to operate in accordance with Category 2 or Category 3, the small unmanned aircraft must be listed on an FAA-accepted declaration of compliance.” I would not assume that your model aircraft has a declaration of compliance on file with the FAA. You must confirm that it does. One way to do this is to call your local Flight Standards District Office.
However, the FAA says, your aircraft would not be covered under a declaration of compliance “if it has been modified outside the configuration and modifications allowed in the remote pilot operating instructions for that small UAS.”
It appears that if you added anything to the aircraft that is not specified in the manufacturer’s pilot operating instructions, that it would put you out of compliance. This could include a parachute system, remote ID module, custom payload, etc.
The aircraft then can’t be operated over people for any reason, even momentarily, day or night.
The final rule discussion says it would not be sufficient for you to modify your drone and then send in an appropriate declaration of compliance. You must have “received from the FAA acceptance of the declaration.”
The FAA will allow the submission of compliance declarations through their website. But before you rush to do that, you need to know “By submitting a declaration of compliance, an applicant would declare that it: (1) established and maintained a process to notify owners of small unmanned aircraft and the FAA of any unsafe conditions that render those small unmanned aircraft non-compliant with subpart D; (2) would correct any safety defects the FAA identified; and (3) would allow the Administrator to inspect its facilities, technical data, and any manufactured small unmanned aircraft and witness any tests necessary to determine compliance with this subpart.”
The Propeller Problem
The FAA also says, “The declaration of compliance establishes the applicant is declaring it has met the applicable injury severity limitations, the exposed rotating parts prohibition, or a combination of these requirements through an FAA-accepted means of compliance.”
I have not mentioned the propeller issue yet. I’ve heard from some people that the propeller guards they have on their aircraft meet the standard. But do they? Not so fast there.
The new standard is that a propeller guard must “prohibit lacerations from exposed rotating parts.” The propeller guards sold now are generally only designed to prevent the impact of a propeller when the UAS collides horizontally with an object. You can easily let a finger slip inside them if you grab the aircraft.
The current propeller guards do not prevent the easy potential of lacerations. The FAA mentions explicitly, “design features such as shrouded propellers can mitigate the risk of laceration,” but such compliant approved shrouds do not exist yet to my knowledge.
The guidance goes on to say, “The FAA clarifies the primary safety objective of the exposed rotating parts prohibition is to protect human beings on the ground from lacerations upon impact with a small unmanned aircraft in typical human encounters and unmanned aircraft operational scenarios (including potential failure modes). The FAA distinguishes between a laceration, meaning a cut that goes all the way through the skin and may require emergent medical attention, and an abrasion, meaning a superficial injury to the skin. Additionally, the FAA uses the expression “typical human encounter” to describe normal impacts, such as an unmanned aircraft impacting a human being due to a loss of control, small UAS failures, or remote pilot error. Exposed rotating parts may pose a significant laceration hazard if they contact human skin, which is unacceptable for the safety of the general public.”
Before you start saying that these guards might change the flight characteristics of the aircraft, you are correct. The FAA has recognized that potential and said, “The means of compliance will address how this requirement is met, and may contain design characteristics and test methods to ensure that the applicant has taken all reasonable measures to mitigate the possibility of lacerations upon impact with a human being. While the inclusion of propeller guards or full body cages could adversely affect the flight performance of the small unmanned aircraft, the safety benefits provided by the prohibition outweigh the potential loss of performance.”
If there does turn out to be a loss of performance, the liability of flight rests squarely on the UAS Pilot in Command to determine the aircraft is safe to fly or violations can occur. Just look at what Part 107 has to say about “safe operation” responsibilities. And the COA pilots and agencies out there should remember their operations need to meet or exceed the oversight that the FAA delivers. If the FAA requires a standard, it applies to COA operations as well.
As part of the FAA discussion, Skydio stated that propeller guards might not be applicable in all situations since their aircraft have emergency propeller stopping mechanisms. The FAA agreed when it said, “Under this rule, blade guards or shrouds on exposed rotating parts are not required if applicants can demonstrate, by a means acceptable to the FAA [emphasis added], that unprotected exposed rotating parts are incapable of lacerating human skin. Implementing a rotor brake or similar approach to stop the exposed rotating part before it makes contact with a person may be effective.” And, “Similarly, folding propellers would be acceptable if the design is shown incapable of causing lacerations in accordance with an FAA-accepted means of compliance.”
Maybe that is an approach that will be pursued to certify and comply with a solution to retrofit drones. No assumptions should be made that the Skydio approach will satisfy the FAA until the FAA actually makes the determination that it does.
The rules for operating as certificated pilots in FAA regulated airspace may be new to UAS pilots, but those who are manned aircraft pilots have had to deal with complex rules and regulations like this from the first day of our flying. None of this should be a surprise to UAS pilots, and these rules are just the tip of what is yet to come.
Concepts like airworthiness and rule compliance are not going away for all legal drone pilots. Instead, drone pilots should begin to embrace the concept that flight operations are a highly regulated activity with severe personal consequences for violating the rules.
Next time I’ll tackle the issues regarding Remote ID and why any celebration of the new rule is unwarranted since there is no technical specification for compliance just yet.