Your article Drones Take Flight in the August 2017 issue of Public Works magazine was very well done. Thank you.

One point of clarification. In the fourth paragraph, you address the need for waivers for operations that aren't allowed under Part 107 certification. One circumstance you cite is when flying within five miles of an airport.

Not true. That rule is an older regulation that's part of flying with a Section 333 exemption. Part 107 requires a waiver only when flying in certain controlled airspaces, which range from Class B to Class G and have different restrictions and spatial configurations. Some controlled airspace starts at the ground and extends to a certain elevation; some start at a certain elevation and extend higher. Part 107 requires pilots to know these airspace designations, be able to read an Federal Aviation Administration sectional chart, and apply that knowledge to understand where you can and can’t fly a drone commercially without a waiver.

More often than not, you can fly much closer without a waiver, the main exception being larger airports. Only a small fraction of airports have controlled airspace that starts at the ground and extends to a certain elevation at a five-mile radius. Here, I randomly picked an area in the Midwest and am looking at sectional data. Only 19 of the roughly 100 airports pictured have controlled airspace that starts at the ground at that five-mile radius. The other 81 don’t have that limitation.

Jon Chapman

My point is I think your readership could benefit from the knowledge that, when flying with a Part 107 certification, the blanket “five-mile rule” doesn't apply. Rather, by applying the knowledge you've obtained through the Part 107 studying and testing process, you'll understand the National Air Space enough to know exactly where you can and cannot fly commercially without a waiver.