ATM Modernization, Commercial, Military

ATC Ready for UAS Integration; Sense and Avoid Is Not

By Woodrow Bellamy III  | February 11, 2014
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Air Traffic Controllers (ATC) in the United States are responsible for around 7,000 aircraft in the National Airspace System (NAS) at any given time. At the current rate of Unmanned Aircraft Systems (UAS) integration into civil airspace, can ATC be ready to manage pilot-free aircraft flying in the same airspace as major commercial airlines, business jets and helicopters?
The answer to that question is a resounding yes, says Chris Stephenson, the terminal operations coordinator for the National Air Traffic Controllers Association (NATCA).  Stephenson, a member of the International Civil Aviation Organization’s (ICAO) UAS study group based in Montreal, Canada, said controllers are already managing UAS flights in civil airspace and will be ready for widespread integration once the FAA provides the regulatory framework and the UAS industry itself provides aircraft that can safely perform complex civil missions such as aerial surveillance, air cargo transportation, weather monitoring and more. 
"Right now, in talking to our en route controllers that work with UAS up in Class A airspace with the Predators and the Global Hawks, they tend to treat them more as a mission than a flight," said Stephenson. "In Class A, they have to either climb up to a restricted area or a TFR or have a chase plane to get up to Class A, which starts at 18,000 feet. Then once they’re in the Class A they can fly on their own."
Most of the civil airspace UAS operations that controllers are currently managing fly within restricted airspace, where few manned aircraft are authorized.  
However, in the future, UAS manufacturers and operators will be looking to use their aircraft for more complex missions. In fact, the United States is behind other countries in the civil use of UAS. For example, there are a total of 2,600 small UAS currently being operated in Japan for agricultural farming. Australia’s Zookal is planning to start delivering college textbooks next year with UAS, and in Kenya the San Francisco-based Airware is using the Aerial Ranger UAS equipped with its autopilot and control software to monitor black rhino poachers. 
The U.S. by comparison only allows the commercial use of two UAS, Insitu’s Scan Eagle and AeroVironment’s Puma, both of which are currently being operated in the Arctic for surveillance purposes. All other uses of UAS are restricted to flying below 400 feet, as the FAA does not allow commercial use of those aircraft.
ATC will be critical to the growth of the commercial UAS industry in the U.S., especially during the initial integration phase as the FAA continues to develop the regulatory framework necessary to certify and fly UAS in civil airspace.  
"To take an extreme example, if FedEx starts flying UAS, we’re going to have to come up with some training and alternative methods of working … we’re not sure how latency is going to go, that’s the amount of time it takes from when a controller gives the transmission or instruction to the point where the vehicle actually performs it.
“When you’re talking a manned aircraft, the pilot generally starts it as soon as he hears it and acknowledges you. With the control station and the UAS vehicle, you’ve got satellite involved and there’s going to be a little bit of a delay," said Stephenson.
But the real key to integration and the use of UAS for more complex commercial operations beyond the current 400-foot barrier is sense and avoid system for UAS, according to Stephenson. Such systems have not yet been developed for UAS.
Stephenson is working with the Radio Technical Commission for Aeronautics (RTCA) committee currently developing Minimum Operational Performance Standards (MOPS) for such a UAS sense and avoid system. 
Sense and avoid systems are chiefly needed so that the FAA can be sure that if a UAS ever loses the data link transmission between itself and the ground control station it is managed by, the aircraft will have a method for autonomously sensing other aircraft and airborne objects, so it can safely avoid collisions and land or return to its operational base. 
"The holy grail of the whole thing is a detect and avoid system, because these aircraft cannot comply with FAR 91.113, which is the see and avoid FAR. Obviously there’s nobody onboard the vehicle to see," said Stephenson. 
"We have to rewrite the regulatory material and everything once they get a detect and avoid system that they have decided is certified and is as good as or better than see and avoid. The work is ongoing and we’ll see how the test sites go. 
“Though I would say we’re looking at several years before you get file and fly situations for UAS."

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