Within a year or two, U.S. companies likely will replace many human workers now flying aerial survey and photo missions or inspecting structures from scaffolds and platforms with missions flown by unmanned aerial vehicles—drones. While the equipment already is available, most firms are holding back until federal authorities issue regulations to govern unmanned aerial vehicle (UAV) use.

The regulations are eagerly awaited by scanning equipment manufacturers, survey firms and contractors that are itching to launch. The rules are being developed at the direction of Congress, which told the Federal Aviation Administration in 2012 to integrate commercial unmanned flights into the national airspace by September 2015.

Some firms already have launched operations anyway, forging ahead on the basis of a variety of legalistic rationalizations, despite some high-profile wrist slapping and, so far, unsuccessful prosecutions by the FAA. Others, poised to launch, are holding back, pending clarification of the regulatory environment. A third set of companies have another approach: They are cutting their teeth on the technology on jobsites outside the U.S. and beyond the jurisdiction of the FAA (see stories on the following pages).

In an "Interpretation of the Special Rule for Model Aircraft" published in the Federal Register on June 25, the FAA "clarifies" its criteria for determining what qualifies as a model aircraft and the circumstances under which FAA rules govern their use.

The agency says it has long held that unmanned aerial systems (UAS)—and model airplanes—are "aircraft" and under its jurisdiction, because unsafe use can endanger safety in the National Airspace System, not to mention people and property on the ground—which the FAA is charged to protect. At the direction of Congress, however, the FAA does offer deference in its rules for flying hobby and recreational model aircraft, as long as those operations are done safely and with equipment that meets its criteria.

The FAA's "enforcement philosophy" on model aircraft has produced only voluntary guidelines, although the agency says it will prosecute operators of any aircraft, models or otherwise, flying dangerously.

The model-aircraft guidelines include flying with community organizations, such as model-aircraft clubs that have adopted FAA's guidelines; not flying over populated areas; avoiding use around spectators; limiting takeoff weight of untested craft to no more than 55 lb; limiting altitude to a maximum height of 400 ft; requiring that model aircraft avoid flying near manned aircraft; and that manned aircraft get the right-of-way.

Further, in 2007, the FAA noted in a clarification of its model-aircraft guidelines that such craft must fly constantly within the line of sight of the operator using "normal vision." It prohibits pilots from using remote vision systems that give a drone's-eye view from the flight deck, saying that method restricts the view of potential hazards in the airspace around the machine. But the FAA's most far-reaching clarification declared that flying machines can qualify as model aircraft and be flown legally in the U.S. only if they are operated "purely for recreational or hobby purposes."

The FAA's definitions of "recreation" and "hobby" are drawn from Merriam-Webster's dictionary: A hobby is "a pursuit outside one's regular occupation engaged in especially for relaxation." "Recreation" is "refreshment of strength and spirits after work; a means of refreshment or diversion."

The FAA states, "Commercial operations would not be hobby or recreation flights. Likewise, flights in furtherance of a business, or incidental to a person's business, would not be a hobby or recreation flight."

Some early adopters challenge the FAA's authority over UAV flights, reasoning that if rules have yet to be adopted, there is nothing to enforce, and the FAA is toothless. Another critic says if the FAA thinks a drone is endangering the airspace by hugging a building to inspect a facade or flying below 400 ft over a single parcel of property, then the FAA's problem is not the drone but that a manned aircraft would be flying so close to a building in the first place. Others, including some UAV vendors, are more understanding of the FAA's position. "Everyone thinks the FAA is dragging its feet, but it's about safety," says Bryan Baker, UAS sales manager for the NAFTA region, Leica Geo- systems. "The U.S. has the most congested and complicated airspace on planet."