Flying the high masts

Completing the light tower inspections with a quadcopter proved feasible, if not always easy, said George Finlay, an AOPA member, a certificated airline transport pilot with more than 10,000 hours flown in manned aircraft, and a certificated remote pilot. Finlay was hired as a subcontractor on an inspection project funded by New Jersey taxpayers that significantly reduced the cost and traffic congestion that would otherwise have resulted from the periodic inspections, according to state officials.

Finlay has in recent years built an unmanned aircraft business, and submitted the winning bid for the project that began in December 2016 and concluded in April 2017 after inspecting more than 200 of the 100-foot structures known as high mast light poles that illuminate busy highways. Many of the 230 flights Finlay logged required some bushwhacking, as the poles are usually situated in medians away from the highway itself and surrounded by undergrowth. Turbulence caused by passing trucks was another challenge. Finlay said the DJI Inspire 1 Pro and Zenmuse X5 camera fitted with a 45-mm lens proved the right system for this job, as he could maintain a safe distance from the structure being inspected and still capture images that were detailed enough to allow lead engineer Bill Mitchell, who operated the camera from a second remote controller, to line up the views he needed to see.

“The resolution was just incredible,” said Mitchell, in a telephone interview. “You could take such great shots, it was amazing.”

Finlay, who began commercial operations under a Section 333 authorization prior to the advent of Part 107, brought aeronautical, regulatory, and airspace expertise to the project that Mitchell said was “more valuable to the whole inspection project than the drone itself.”

Several towers were located in areas where airspace authorization was required, and securing the necessary approvals was part of Finlay’s job, along with serving as remote pilot in command. Finlay said the process of securing FAA approvals where required went smoothly: “It wasn’t a show-stopper by any means.”

Mitchell was primarily focused on finding cracks or other structural defects that would indicate a danger of structural failure, which has been known to happen. Glenn Stott, the unmanned aircraft systems coordinator with the New Jersey Department of Transportation’s Bureau of Aeronautics, has been working with counterparts in other states as well as his own staff to explore a range of potential missions and applications for drones.

“Our UAS program is looking to capitalize on the efficiencies of drones for all inspection missions,” Stott said in a telephone interview, adding that mapping, 3-D modeling, and measuring the volume of piles of material are also missions well-suited to drones, which can complete such jobs in significantly less time, at lower cost, and with reduced risk to personnel and the traveling public. In October, he hosted a gathering of counterparts from five state transportation agencies to share best practices and lessons learned.

“It was very, very successful,” Stott said, adding that the U.S. Department of Transportation is paying attention, and plans a larger gathering for the same purpose this month. “They’re looking to have it as a national program now.”

Mitchell said that his own employer is also contemplating what other types of infrastructure inspections can be handled with an unmanned aircraft. Flying with Finlay was Mitchell’s first exposure to unmanned aircraft systems, and he came away convinced that while they may not be the only tool needed for every job, drones will certainly be an important tool for inspection of bridges, high-voltage power lines, and other hard-to-reach structures. While the drone has limits, it certainly beats a pair of binoculars—another method used for some such inspections in the past, or a high hoist by a bucket truck requiring hours of setup and lane closures, and the traffic congestion that ensues.

Mitchell said that the low-angle winter sun also complicated matters a bit, limiting the hours when the structure would be sufficiently lit to capture images with the detail required.

“If we did it in the future with this same situation... I would suggest doing it in the summer,” Mitchell said.