Photo: NASA
Photo: NASA

Will drones ever carry passengers?

People may someday fly on drones, but only if a lot of technological challenges can be addressed.

Will autonomous passenger flight become a reality? Short answer: no one knows.

That might be hard to believe, given the way the aviation industry and Congress have committed so publicly to wholesale integration of unmanned aircraft into the national airspace. If there is a realistic timeline somewhere, it’s likely that it calls for this integration to come in stages. 

Short-range package delivery in rural areas has already started. The next step would likely involve heavier cargo carried over longer distances in increasingly larger rotary- and fixed-wing aircraft. And finally, carrying passengers, probably initially in urban areas in electrically powered air taxis. For now, though, those windshieldless jumboliners remain just a twinkle in futurists’ eyes.

How far along are we already, and what needs to happen to take the next steps?

The last time I visited Singapore, drones were making package deliveries to the thousand or so cargo ships moored in one of the world’s busiest harbors. That seems an easy, practical, and highly useful way to take advantage of current drone technology. Rather than having to send a small boat or manned helicopter out to a ship, you could much more inexpensively dispatch a small quadcopter drone, guided by GPS, to deliver anything from emergency medication to an order for a pizza and a six-pack.

The biggest challenge, if the service starts to catch on, would be making sure the drones don’t run into each other. So traffic control is important. Still, if not much manned helicopter traffic were in the area, and all the routes were over water, the risk of any collision would likely be limited to losing the drone and the cargo.

Consequences ramp up quickly, however, as the drones get bigger, fly higher, and venture into airspace over populated areas. While it might be enough to simply monitor the position and routes of delivery drones over water or sparsely populated land, some form of telemetry-driven sense-and-avoid technology would be required in tighter quarters. Development of that technology is ongoing and parallels the advances we see in self-driving automobiles.

The telemetry piece is critical. Not only would each drone need to sense and avoid its neighbors; it would also need access to what those other drones’ next moves are going to be, no matter how small. This crowdsourcing technology is critical if self-driven cars are to become mainstream. Second-by-second updates on turns and lane changes could be shared in a cloud of data available to all virtual “drivers” on the highway, enabling closer spacing and thus, less traffic congestion, faster speeds, and improved efficiency. Particularly in an urban environment, this technology would be a must-have safety feature for autonomous flying drones—whether carrying packages or passengers.

While this electronic infrastructure is vital, it’s the aircraft themselves that have been getting most of the attention. Conceptual rotorcraft designs are on the CAD-CAM screens of most of the major manufacturers. Configurations include everything from single-seat “flying bikes” to detachable minivan-size pods suspended beneath a multi-rotor mother ship. In the urban environment, all-electric, fast-charging designs are thought to be the most practical, since the mission involves short distances. For longer flights, the jury is still out on how electric a hybrid needs to be.

Battery development is key in that decision. Have we reached a plateau in battery potential with lithium-ion? Or is there an equivalent in battery technology to Moore’s Law in computer processing capability? With the potential for reducing battery weight and increasing endurance a moving target, the extent of future roles for fully electronic aircraft remains a question mark.

Safety has to be the primary driver in any future passenger-travel platform. Commercial aviation’s current safety record came about only through layer upon layer of checks and triple-checks from design to production to operations. And as we have seen recently, there are still cracks in the fortress walls. Autonomous flight will have to double down on that safety culture if the last layer of defense in an emergency—the pilot—is to be removed from the equation. While it’s true that automation can perform most of the duties of flying an airplane more reliably and efficiently than a human pilot, the machine can only do what some human somewhere has “taught” it to do.

Artificial intelligence and machine learning could advance to the point where the machine can actually “outthink” a human pilot. But we’re not there yet. How smart would drones have to get before you would be willing to trust your family to one?