Drone Flights Near Towers
The National Association of Tower Erectors (NATE) has written, with the expertise of its UAS Committee and others knowledgeable about drones in commercial operations, a handbook entitled “Unmanned Aerial Systems Operations Around Vertical Communications Infrastructure.” The six page document provides some very useful, but general guidance about the unique aspects of using a UAS in proximity to the structures with which its members work.
This publication includes topics such as UAS utilization guidelines based on the FAA requirements. The authors then review flight operations, training provisions, documentation, safety reporting, emergency procedures, weather requirements, noise abatement and hours of operation. It states that the organization’s primary goals were to maximize the safety of tower technicians, ground personnel, the general public and flight operations. Similar expressions of intent were included in many of the FAA §333 applications as the public interest basis for granting exemptions.
Unfortunately the FAA’s proposed approach, upon which NATE’s guide is based, to drone regulation can be described as “one size fits all”, rather than EASA’s effort to use SMS-like principles to match the risk of the operation with the degree/level of restrictions/freedom for the drone operation. NATE’s effort moves the focus from the FAA very macro approach to one iteration closer to what its members are likely to encounter in their work with towers.
If this handbook could reach one greater degree of granularity, the guidance would become even more powerful as a safety tool. For example, the association’s pamphlet identifies the three major categories of Vertical Communications Infrastructure—
The physical characteristics of each, the positioning of the drone in relationship to equipment to be inspected and the currency/signals emanating from these three types of tower each pose different profiles for risk to the operator. If those unique characteristics could be catalogued and matched against the capabilities/frailties of the drones, a very useful matrix could be designed.
The experience of those who have worked in these lofty work environments could add more precision to the handbook. For example, procedures could be created to deal with the possibility of a cellular tower which catches fire.
That section could include not just tactics of how to respond, but data of the frequency of such incidents, the magnitude of the fire/explosion and possible pre-flight checks to minimize the likelihood of such a risk.
Weather is another variable which might be discussed in greater detail. What factors contribute to the likelihood that the structure would attract lightning would be extremely valuable. The handbook mentions wind as an element to be considered, but the truly telling assessment be the multiple cross-indexing wind speed with the UAS’s operational capacity to respond to winds and the structure’s tolerance for contact. A powerful drone may be safe to operate in higher winds if the tower is relatively insensitive to a bump, for example.
Much more information may enlarge a five page paper to an impractical encyclopedia of threats and solutions; so at some point, it may be worthwhile to recite other things to be considered: the existence of guy wires, the susceptibility of some drones’ GPS guidance to the electromagnetic/radio interference from the infrastructure, etc. OSHA has a website which lists many safety considerations.
Certainly each company using the NATE document as a very helpful foundation and design more specific SMS-like manuals for the risks which its operations pose.