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What Is a Drone, Anyway?


Launching a Puma drone

Soldier launching a Puma drone

At a time when drone aircraft have become a daily feature of the news and are about to proliferate in U.S. airspace, it’s a good idea to take a step back and examine a very basic and very important question: What, exactly, is a drone?

The answer turns out to be more complex than might be expected. Strictly speaking, a drone is an unmanned aircraft that can fly autonomously—that is, without a human in control. But even that seemingly simple definition quickly runs up against the nuances of how contemporary unmanned aircraft are flown.

For example, consider an aircraft that is under the control of a remote pilot for most but not all of a mission. If the pilot switches to a GPS-guided autopilot mode for a few minutes, does the aircraft become a “drone” for that subset of its flight, and then lose that designation once the autopilot is switched off? Or does the presence of the GPS autopilot, regardless of how much it is actually used, make it a drone?

(Even when autonomous flight does occur, the human element is still very much present but simply shifted in time. Designing systems and methods to successfully allow a computer to control an aircraft is a high art in and of itself. Autonomous flight is made possible by the tremendous amount of human ingenuity invested well in advance of an actual flight.)

Many people (the author included) have used “drone” to describe any aircraft without an on-board pilot. But that is an oversimplification that masks the incredible range in shapes, sizes and capabilities that characterize today’s unmanned aircraft. And it can fail to fully recognize the high levels of skill involved in piloting—whether or not the pilot is actually in the plane.

As the following questions and answers show, some types of unmanned aircraft clearly are not drones. Others clearly are. And in some cases, the distinction is a matter of perspective.

Are traditional model airplanes “drones”?

In a word, no. Here’s why:

Model airplanes have been around for well over a hundred years and actually predate manned flight. Models have been used for decades to test aircraft design theories and to validate full-scale performance. Some models are small-scale replicas of real airplanes; others are original designs intended for sport or competitive activities. In many cases, they are built to stunningly precise levels of detail. Most, though not all, model airplanes today are flown by radio remote control.

Model aircraft are flown by thousands of enthusiasts with a common interest in aviation and a love for watching their aircraft fly and perform. For this reason, models are largely flown within visual line of sight and in the presence of an operator who watches and maintains control of the airplane during flight. That alone is enough to place model airplanes cleanly outside the boundaries of “drone.”

Are Predators, Global Hawks and other military unmanned aircraft “drones”?

Predators and Global Hawks are two of the many types of unmanned aircraft that have been used by the U.S. military in Afghanistan and elsewhere. They are piloted by extremely skilled aviators who, thanks to a combination of technology advances, no longer need to be physically sitting in the airplane. However, that doesn’t make them any less skilled than traditional in-the-cockpit pilots.

Sean McEntee, a lifelong model airplane hobbyist and current U.S. military UAV (unmanned aerial vehicle) pilot who has flown surveillance missions over Iraq and Afghanistan, brings a unique perspective to the challenges of remote piloting. He explains that flying a UAV involves far more than “sitting in a box and watching it fly around.” Many UAVs, he says, are flown “stick and rudder,” with controls comparable to those found in the cockpit of a traditional airplane. U.S. military UAV pilots often go through a rigorous screening process followed by a year or more of intensive training.

Largely for these reasons, many unmanned aircraft pilots take a very dim view of the term drone, as it fails to recognize the high levels of skill involved in real-world flight operations. They often prefer designations such as UAV or RPA (“remotely piloted aircraft”).

What is a “first-person view” unmanned aircraft? Is it a drone?

A first-person view (FPV) aircraft has a front-facing video camera and transmits real-time video to an operator on the ground. The operator looks at the image on a computer screen, sees the view as if he or she were sitting in the cockpit, and flies the plane accordingly.

While “UAV” is a general term for (non model aircraft) unmanned aircraft, FPV refers to the subset of such aircraft that are flown by a remote pilot using the image transmitted from an on-board camera. Unmanned aircraft guided exclusively by GPS or on-board computer analysis of imagery are UAVs, but they aren't first-person view UAVs.

Until now, most FPV aircraft have been operated by the military, using technologies that make it possible to fly the aircraft beyond the line of sight of the pilot. However, use of FPV aircraft in non-military settings is certain to increase with the recent enactment of a new U.S. aviation law that will open U.S. airspace to many types of unmanned aircraft in the coming years. FPV aircraft are likely to be subject to very conservative FAA rules regarding domestic non-line-of-sight operation to minimize potential safety concerns. For example, if the communication link between the pilot and the aircraft fails, then there are obvious challenges involved in bringing the aircraft back to the ground without endangering other aircraft or people on the ground.

Is an FPV aircraft a drone? Under the strictest definition of drone, it isn’t, since it is flown under the control of a human operator. However, when flown beyond the line of sight, an FPV aircraft would be characterized by many people as a drone, despite the significant skill that might be involved in flying it. This is because the definition of drone can be difficult or impossible for an observer to apply. After all, how can someone who sees an unmanned aircraft maneuvering without any evidence of a nearby pilot know whether it is autonomous or remotely piloted? From the observer’s standpoint, it’s not unreasonable to consider it a drone.

What about an unmanned aircraft that navigates itself by GPS?

An unmanned aircraft that flies autonomously, using GPS to navigate a complex flight path without human control, falls squarely within the definition of drone.

Are hobbyist “drones” really drones?

Usually, yes. Many drone hobbyists have an extremely high level of expertise regarding systems for autonomous flight. They use this expertise to merge robotics, sensors, and airframe design in an amazing variety of innovative ways. In addition, they are often very careful in their use of terminology. If a serious hobbyist calls his or her platform a “drone,” that is almost certainly an accurate designation.


So where does all of this leave things? To start, it’s important to recognize the enormous amount of research and innovation that is occurring in the commercial world, the military, and the hobbyist community with respect to autonomous flight. However, when we read about U.S. military “drones” we should also keep in mind that skilled aviators continue to be a critical part of military aviation, even if they happen not to be on the plane.

Finally, despite all these changes in the aviation world, it’s important not to lose sight of what hasn’t changed at all: Aircraft fly thanks to a mix of physics and human ingenuity. That has been true since the dawn of powered flight, and remains no less true today.

Image courtesy AeroVironment, Inc.

The views expressed are those of the author and are not necessarily those of Scientific American.

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