Last week, NAAA sent a letter to the FAA explaining why a policy proposal the agency is considering would be detrimental to manned aircraft and all low-level aviators. While considering exemption requests for UAVs to conduct powerline inspections, the FAA is considering the concept of “infrastructure masking” as a valid mitigation technique to keep UAVs and manned aircraft separated.

Infrastructure masking is the concept that because manned aircraft are supposed to avoid obstacles, UAVs can operate close to these obstacles without interfering with manned aircraft activities. The UAVs near these obstacles could then potentially have the right-of-way over manned aircraft.

This policy would be detrimental to low-flying manned aircraft due not only to small UAVs being notoriously difficult to see but also due to their operators not having to be present to control them from colliding with manned aircraft.

NAAA explained the unique operational environment of aerial applicators requires them to constantly maneuver tightly around utility wires and poles to treat surrounding crops. The letter went on to explain aerial applicators already face high cockpit workloads and constant threats from other low-level obstacles. The letter included the following text pertaining to Part 137 accidents: 

In the 10-year period between 2009 and 2018, there have been an average of 8.6 wire strike accidents and 1.7 tower collision accidents per annum. Over that same 10-year period, 13 of the wire strike accidents and 8 of the tower collisions were fatal. Adding UAVs as an additional obstacle in this already dangerous environment is likely to increase accidents.

The letter also explained that in addition to wires, there are many other obstructions that are a danger to low-level aviators, such as meteorological evaluation towers, radio communication towers, towers supporting powerlines and wind turbines. Along with the letter, NAAA included an accident report detailing the perilous effects of these obstacles. The report showed from 2008 to 2018, there have been 22 Part 137 accidents from collisions with these obstructions resulting in nine fatalities. For all of general aviation, there have been 40 tower related accidents and incidents resulting in 36 fatalities over the same 10-year period.

The letter closed by saying NAAA is aware of the important functions that can be accomplished by UAVs, but at the same time protecting the safety of current and future users of the National Airspace System is mandatory.