On November 17th and 24th, 2016, I wrote two articles titled: Aircraft Accidents and UAS Data, Parts One and Two, respectively. My article’s information referenced research conducted into the safety of Unmanned Aerial System (UAS) vehicles. The much anticipated follow up journal paper has recently been published by the team of aviation authors: Ryan Wallace, Kristy Kiernan, Tom Haritos, John Robbins and Godfrey D’sousa, all hailing from the respectable Embry-Riddle Aeronautical University (ERAU). They have published the second journal paper in the International Journal of Aviation (IJI), Aeronautics and Aerospace, titled: Evaluating Small UAS Near Midair Collision Risk Using AeroScope and ADS-B.
The team of aviation authors’ first IJI article from 2016 placed a Cessna 172S G1000 aircraft in ‘harm’s way’ in a controlled environment by having a test group of different aged pilots identify an unmanned aerial vehicle (UAV) while conducting normal flight maneuvers. One aspect of the tests was that the pilots expected the UAV in their midair neighborhood, but were not told of where. The results were alarming, not in pushing any narrative that suggests UAVs and public aviation don’t mix, but in that the UAVs were still difficult to perceive (detected between 0.10 and 0.31 statute miles away), identify and react to their presence, e.g. avoiding close encounters.
This second IJI article was more aggressive and, in this writer’s opinion, more telling, in the information they presented. What must be distinctly understood is that this group of researchers are pro-unmanned aerial vehicle technology and use – as am I; my interest being from a business standpoint. Indeed, it is the authors’ commitment to UAS industry success that gives them a unique position that can promote the advantages while simultaneously strongly warning of how UAV platforms, particularly small unmanned aerial system (sUAS) platforms, can be misused by those without the proper discipline. As this writer interprets the term: ‘sUAS’ is (in the IJI report) an amateur-operated UAV; it is not operated professionally by an approved business interest, e.g. real estate firms, marketing firms, professional photographers or agriculture consultants. However, the sUAS platform is large enough to hinder the safety of the National Airspace System (NAS) and small enough to be practically undetectable with the human eye at aircraft-operated speeds and technological identifying means.
There were four research questions the team sought to answer:
- “What are common characteristics of sUAS flight locations?”
- “What are common characteristics of sUAS operations?”
- “What is the potential impact of detected unmanned activity to aerodromes and aviation operations?”
- “How effective are geo-fencing restrictions in preventing sUAS flights from entering protected areas?”
The author team employed an applied research method; they utilized “exploratory research and case study approaches.” To do this the team had access to a Dà Jiāng Innovations (DJI) Aeroscope mounted to the top of a three-story education building near Daytona Beach International Airport (DAB); the DJI Aeroscope, as per DJI’s website: www.dji.com/aeroscope “is able to identify the vast majority of popular drones [UAVs] on the market today by monitoring and analyzing their electrical signals to gain critical information, allowing users to protect the integrity of their flight-sensitive environment”. The Aeroscope was used to detect small unmanned aircraft near the airport for a thirteen-day period.
Even with this advanced means of detection, this equipment was fairly limited – technologically. The DJI Aeroscope only detects DJI-manufactured sUAS platforms; the Aeroscope detects only platforms within electronic line-of-sight; some DJI platforms could not be identified and the authors did not assess environmental or seasonal factors, e.g. weather conditions. However, DJI has a large market share of UAV and sUAS sales (72%), which increases the finding’s credibility.
When detecting these platforms, one must remember that this is a three-dimensional tracking. For example, when observing proximity to an airport runway, the X-axis is the straight line distance to the end of the runway; the Y-axis would be the straight line distance to either side of the runway. Just as critical is the Z-axis, representing the vertical space above the runway that intercepts an aircraft’s flight path on take-off, approach or turning. By contrast, the sUAS’s owner has the limits of a human eye’s view of, e.g. a runway; the sUAS can see straight down the runway, but fail to see the aircraft approaching from behind.
The report opens with a February 2018 event: an sUAS’s video footage hovering behind a Frontier Airlines A320 on approach to McCarron airport. This sUAS, hovering in the space that the A320 passed through is disturbing enough, but it is also unable to ‘see’ any other aircraft following the A320’s flight path into the airport. How dangerous is an impact between an sUAS and a major aircraft?
The University of Dayton (UoD) released a video of a controlled collision, showing a 2.1-pound sUAS impacting a Mooney M20 wing at 238 miles per hour. Please review the video:
What must be taken away from this experiment is that the M20’s curved leading edge is structurally stronger than a flat panel would be; despite this fact, the sUAS disappears into the leading edge. Behind the leading edge is one of the aircraft’s fuel tanks. Is it unlikely that one sUAS can hit the narrow profile of an aircraft’s leading edge? Yes, I repaired a B727 that ran into a flock of geese that structurally damaged six separate points on both of the B727’s wings’ narrow leading edges; four slats and one Krueger flap were replaced because of the extensive damage.
In addition, even with the damage incurred by the UoD wing, the aircraft might – might … still fly to an emergency landing; remember, an sUAS is electrically powered entering a fuel cell, while a goose is not. However, the same sUAS hitting the turning main rotor of a helicopter would be catastrophic. The helicopter is solely dependent on the main rotor system to remain airborne; each main rotor blade must be balanced with its opposing rotor blade(s) to maintain flight; if even one blade is damaged or shattered by a similar sUAS impact, the helicopter will not stay in the air.
The authors found sUAS activity came as close as within a half mile (X- and Y-axis) of DAB’s location; some sUAS were found to be flown above 1000 feet (Z-axis). The report shows high-altitude sUAS flight activity along nearby Ormond Beach, where patrol helicopters and banner towing operations are frequently found. The report states, “These findings demonstrate that at least some sUAS operations are penetrating altitudes traditionally reserved for manned aircraft operations.”
The effectiveness of Geo-fencing was reviewed. Per the report, “Geo-fencing is one or more location-specific, programmed flight restrictions or limitations designed to prevent or restrict sUAS flights over or near areas that would create a security or safety risk.” There are four categories of Geo-fencing zones: Warning, Enhanced, Authorization and Restricted; each is designed to alert sUAS operators of flight restrictions, yet each restriction can be overridden depending on the operator’s unlock capabilities. It is unclear if aircraft operators receive a similar warning of an sUAS trespassing in the area.
In defense of sUAS operations, the report states, “This data suggests that a preponderance of sUAS operators are flying for personal use around their own residences.” The authors then comment, “The authors were particularly concerned that nearly 97% of all detected sUAS flights had been conducted within five statute miles of one or more aerodromes”; an aerodrome is defined as a small airport or airfield.
The IJI article’s authors are also taking a hard look at a smaller international airport: DAB, whose number of operated flights are considerably less than Kennedy, Los Angeles or O’Hare airports. These three major airports – and many more – have seen an increasing number of sUAS sightings in close proximity to the approach paths and altitudes used by major airliners. DAB, for its size, is demonstrating an increasing congestion of sUAS activity, as is its surrounding area.
The IJI article is a snapshot. It does not definitively say one group, sUAS operators, are a danger. However, the sample population data presented suggests that the general public has a long way to go in cultivating a safe environment for the flying public, that the data cannot be ignored or trivialized. It truly is no longer a matter of ‘if’, but a matter of ‘when’.
Next week I will revisit this IJI article to discuss concerns the report raises about policing our NAS. I highly recommend that readers review the IJI authors’ report.