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Unmanned Aerial Vehicles
Fear of Crashes Keeping Drones out of U.S. Airspace
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By Grace V. Jean
Imagine that for your next trip out of town that you could drive to the nearest airstrip, climb into a small robotic aircraft, push a button and then sit back and relax as it flew to your destination.
Sound too much like science fiction? Not if David Vos gets his way.
As senior director of unmanned aircraft systems and control technologies at Rockwell Collins, Vos and other industry representatives are advocating a push for the development of automation technologies that will make it possible for piloted aircraft and drones to fly safely in the same airspace.
Federal regulations prohibit unmanned aircraft from flying in civilian airspace. But as the number of drones in war zones has skyrocketed, there has been some discussion about operating such aircraft in national airspace. The Federal Aviation Administration has balked on the issue because of safety concerns. But with the Department of Homeland Security and other agencies beginning to fly more drones for stateside missions, the debate about incorporating them into commercial airspace has taken off.
“There’s a big dialog, but it’s a dialog in which the boat has already left the harbor,” Vos tells reporters during a briefing at the annual Association for Unmanned Vehicle Systems International symposium in Washington, D.C. “For anyone saying, ‘We cannot do this,’ get on the boat, because it’s not turning around.”
Vos contends that technologies that currently allow many of the military’s unmanned aircraft to automatically take off, fly and land can be applied to conventional airplanes and will help to speed up the airspace integration process.
Rockwell Collins outfits many of the military’s drones with automation technologies. Vos is quick to point out a statistic: Every 20 minutes, an unmanned aircraft with its onboard flight controls completes a successful automatic landing.
The company has initiated some demonstrations to prove that the automation technology is feasible. Working with Aurora Flight Sciences, it integrated flight control technology aboard a Cessna and completed an autonomous take-off and landing demonstration in Scotland.
“All we’ve done is change the parameters to accommodate the different vehicles,” Vos says. The demonstrations prove the transportability of these capabilities across all manned aviation, he adds.
“They’re all aimed at a future where we don’t need to stand in big lines at local airports to fly short-hop flights. We want to go to our own airport with our own little airplane, push a button and fly to the next airport,” he says. “This is not dreamland, this is reality. This is going to happen and we will get there with these kinds of capabilities.”
The enabling piece of the concept is the automation, high reliability, and redundancy of the flight control system that permits automatic landings without requiring massive ground infrastructures, he points out.
“We have tens of thousands of airstrips around the country. If we had to put landing systems in, in order to enable automatic landings, we would break the bank before we even started,” Vos says.
The whole point is to incorporate the autonomy control system onto the airplane itself. During normal flight, that automation might not be necessary. But in an emergency situation, the system is available when the pilot needs it. This “digital parachute” could be deployed for an emergency landing, Vos says.
He shows a military test flight video of the company’s control systems aboard an unmanned aircraft that has its wing blown off intentionally during a trial. The plane was able to recover and compensate for the damage, continue flying and land safely.
The manned aviation world, however, remains largely fixated on a concept called “sense-and-avoid,” in which piloted aircraft and unmanned systems would rely upon onboard sensors and other visual data to avoid potential collisions.
“Sense-and-avoid is not a panacea,” says Edward Falkov of Russia’s State Institute of Aviation Systems, GosNIIAS. Even if the best sensors and vision technologies are put onto an aircraft, it’s what is done with the feeds that matter, he points out to the conference. Unmanned aircraft should be seeking to operate within the constraints of existing systems, and innovations should not impact airspace management.
“If you have good separation, then maybe sense-and-avoid is not needed at all,” he says.
The problem with that argument, others say, is that there are myriad aircraft flying in airspace today, ranging from commercial jetliners to balloon enthusiasts and civil aviators to skydivers. Not all of them carry transponders, nor are they required to. And when air traffic management fails, the consequences can be tragic.
“We all know this is a problem. Look at the crash between the helicopter and plane in New York City,” Vos says, referring to the Aug. 8 collision above the Hudson River that killed nine people. “Honestly, do we really want to develop the future of air traffic management and air traffic control to match that kind of performance? I think not,” he says.
Most experts agree that there must be a sensor package to enable aircraft to perceive the environment and avoid mid-air collisions. But the airborne sense-and-avoid answer is still years away, says Andrew Zeitlin of the MITRE Corp. No single technology seems to provide all the data needed for the activity, he adds. But he remains optimistic that airborne sense-and-avoid can become a realistic solution in time.
“Four to five years is possible if we get a lot of resources and the technology doesn’t disappoint,” he says.
But so far, there is a ways to go. Sensors are still in an evolving state and small ones, especially, are limited in performance, he points out.
Algorithms are another big shortfall. There is no industry standard yet, and more work will be required to converge on the best one that fits the unmanned sense-and-avoid applications, says Zeitlin. “We recommend that in order to explore the safety case, that a comprehensive modeling and simulation program be done,” he says.
Today, researchers can look at air traffic radars to see what encounters occur between manned aircraft. To study how unmanned systems might impact the airspace, they can overlay planned flight operations over current traffic patterns to determine the probability of collisions. Modeling those situations could help the government compile standards, Zeitlin says.
One possible solution is to provide airborne sensors that will connect automatically to other aircraft and detect traffic in the airspace.
“You want to be able to do what your Bluetooth device does: As soon as you get in range, it connects,” says Vos. When an aircraft enters the airspace, it would have connectivity to everyone else within a certain range of, say, 100 nautical miles. As new aircraft came into its airspace, they, too, would connect automatically.
“With that ad hoc networking, clearly you have the ability to do real integrated air traffic control,” says Vos.
The entire air traffic system must be managed holistically instead of case-by-case. Currently, aircraft may fly as they please and they rely upon air traffic controllers to spot trouble areas.
“Collision avoidance drops off in a much better way when you’re doing management of traffic rather than reactively addressing potential collision,” says Vos.
The FAA is updating the current ground-based air traffic control system to a newer satellite-based system in a program called Next-Generation Air Transportation System. A key component is the Automatic Dependent Surveillance-Broadcast technology. ADS-B will provide aircraft with radar-like displays of real-time traffic, maps, weather services and flight safety information.
ADS-B will broadcast via two datalinks in the United States: 1090 MHz Extended Squitter and 978 MHz Universal Access Transceiver.
Ground stations are being developed and gradually will be installed by the FAA to provide surveillance of aircraft and to rebroadcast traffic data from one datalink to the other.
ADS-B is not yet implemented in U.S. airspace. “The proposed mandate is still years away,” Zeitlin says. The effort requires more money to accelerate the technology and the equipage of aircraft by 2020.
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