Unmanned aircraft systems (UAS) have proven their utility in military theaters in a variety of applications, and they hold the same potential for civilian operations. Government and private-sector interest in using unmanned aircraft for missions such as border patrol, aerial photography and land and crop surveying has been building for years. Outside of combat operations, the military requires freer access to domestic airspace to maintain UAS training proficiency.
But introducing UAS into the National Airspace System (NAS) with airline, cargo and general aviation traffic poses substantial technological, regulatory and safety challenges. FAA is addressing the issue within its Aviation Safety office and Air Traffic Organization. The agency expects to publish a Notice of Proposed Rulemaking in 2011 establishing conditions for the operation of small UAS in the NAS. An RTCA Special Committee, SC-203, is working with industry to define Minimum Aviation System Performance Standards.
What is the progress toward integrating UAS in civilian airspace? What are the expected milestones toward this goal, and what are the significant remaining challenges? For the answers to these questions and others, Avionics Magazine assembled a panel of industry and government experts for a recent Webinar, “UAS Civil Airspace Integration: Progress and Challenges.”
John Walker, president, JS Walker Group Aviation Solutions; co-chairman RTCA Special Committee 203, Unmanned Aircraft Systems
The United States is the only civil airspace where unmanned aircraft systems are allowed routine access. It’s important to recognize that we do have access to airspace now, but it is limited. What we’ve been doing with our RTCA activity for discovering standards, recommended standards for the FAA is going to be very important.
The one notion that I want to put to you is how we can associate safe access for civil UASs using NextGen technologies. How can we use ADS-B? How can we use performance-based navigation? How can we use communication so that when an unmanned aircraft is operating in civil airspace that aircraft is operating and performing like any other aircraft? That is going to build confidence. It’s going to build safety. It’s going to build where an aircraft, whether the cockpit is on the ground or in the air, can move safely through the airspace.
‘[Civil UAS integration] is not something that will be done just by the federal government or by industry. It’s through a collaborative process.’
— John Walker, JS Walker Group Aviation Solutions
It’s important to look at the dynamics of what civil airspace challenges are. There’s a phenomenal amount of work that’s being done right now as far as with sense and avoid. How can aircraft be using sense and avoid using communication, using navigation, operate and perform, looking like any other aircraft. The RTCA Special Committee 203 program was requested initially by the Aircraft Owners and Pilot’s Association, and one of the things that is being looked at now is how the capabilities and technological advances for unmanned aircraft be used by civil aircraft, and especially for general aviation aircraft.
It is also important to understand how we’re going to do that. This is not something that will be done just by the federal government or by industry by itself. It’s through a collaborative process. We need to really pursue the issues of alliances and partnerships. This is akin now to something that occurred in the early 1960s about going to the moon. I believe that. We need that kind of cooperation.
There has been a great deal of work done in RTCA Special Committee 203. We have achieved a lot in the six years we have been together. Most importantly, we have the only two DO documents that address what the road to the standards will be for minimum aviation system performance standards. We have identified what the deliverable dates will be. We work very closely with EUROCAE Workgroup 73 in Europe and there’s an ICAO JULIA study group. So what we’re doing for RTCA will influence what happens on a global basis.
Andrew Lacher, UAS Integration Lead and Research Strategist, MITRE’s Center for Advanced Aviation System Development (CAASD)
The community’s vision for unmanned aircraft is that they operate together with manned aircraft in non-segregated civil airspace. In the United States, we fly a fairly large number of UASs on a fairly regular basis, but they don’t really operate routinely. Each UAS operation has with it a certificate of authorization (COA) or a waiver, which is individually scrutinized and approved by the FAA. When we operate unmanned aircraft in non-segregated civil airspace, both the operators of the UAS and the legacy users of the airspace, as well as the FAA, want to ensure that those systems can be operated safely.
There are a number of key challenges that we face when we move to this fly by wireless system. We still have a pilot in the cockpit, if you will, but the cockpit now is separated from the aircraft and the flight crew is separated from the aircraft, and linked to the aircraft via a command and control communications link, which has in itself some vulnerabilities.
We also no longer have the pilot’s eyes in the aircraft. This makes it difficult to follow some of the existing flight rules. Another major challenge is dealing with how unmanned aircraft with the vulnerabilities and latencies associated with the command and control link would fit into our existing air traffic control system.
‘We also no longer have the pilot’s eyes in the aircraft. This makes it difficult to follow some of the existing flight rules.’
— AndrewLacher, MITRE Corp.
We see these three big challenge areas, involving significant technical operational procedural, as well as policy components to their resolution. There are some other issues associated with unmanned aircraft as being originally developed as experimental aircraft for military purposes, not necessarily being developed originally to the same level of reliability as manned aircraft. But we do know how to build a reliable aircraft. We just need the policies to follow those standards. The other is some issues with the qualifications of the flight crew. There still is a pilot in command who is responsible for the safe operation of that flight, but that person may not have or need the same background that a traditional manned aircraft pilot might have. But again, we know how to determine crew qualifications and training. So it’s more of establishing the right policies.
Looking at the see-and-avoid requirement, what the community is doing is starting to look at sense and avoid. That is a technology that would provide and augment the pilot, who is now on the ground, with an electronic capability of sensing aircraft around them and being able to remain safely separated from other traffic, and avoid collisions. If you remove the pilot’s eyes from an aircraft, now if two aircraft encounter each other in some sort of conflict, you now reduce by 50 percent the probability that the pilot in the manned aircraft will see the other aircraft. However, if we create some sort of technology that will allow it to sense aircraft around it, we still can provide, either through the pilot or through automation, the ability to sense and avoid other traffic.
On the command and control link, by introducing a communications link between the pilot and the aircraft, we have the potential to interrupt the ability of the pilot to maintain operational control of the aircraft through vulnerabilities in the communications. If you’re controlling an aircraft through a wireless communications device, you will occasionally have interruptions in that link. The community is working toward identifying protected spectrum for the command and control link for the unmanned aircraft pilot to link. Today, these aircraft will typically transpond that their link is broken by transponding that they’ve had a radio failure. Unmanned aircraft lost link procedures are different. The one thing they all have in common is that none of them will fly the ATC clearance that they were last given by the controller. The controller does not know necessarily what the aircraft may do.
There are some other issues from an air traffic controller perspective, potentially adding increased workload due to things like response latencies. Some preliminary analysis that we’ve done at MITRE has shown the communications latency could be approximately three times as much as the communications latency between a manned aircraft and a controller as compared with an unmanned aircraft and a controller.
Rose Mooney, Director of Engineering, AAI Corp.
In 2006, FAA came out with a ruling that grounded all UAS operations in the NAS. Up until that point, all of the major manufacturers had done their testing on their own research and development money.
Now, UAS operations are controlled by FAA and rules are being written. But UAS flight operations are only permitted in either restricted airspace or in the NAS through the COA process, which is very time consuming and expensive, and can only be had by public entities, which means manufacturers for new designs have very limited access to flight space and airspace time to develop new UAS.
‘As manufacturers, we do not have access…. We really need that to compete not only in the U.S., but also internationally.’
—Rose Mooney, AAI Corp.
DoD UAS programs of record were safely tested in the NAS using our research and development dollars and were often restricted in design by a number of limiting factors and requirements, which included a certain amount of commercial off-the-shelf types of instruments and equipment, cost barriers, whether they fit certain size, weight for being expeditionary. The other thing that many people are unaware of is most of the programs of record and the competitions that the UAS manufacturers have is that we were actually required to have fly-offs for each of these programs. But we also were bought by the intelligence community. So it wasn’t even an aviation culture. Now, all of the services have moved to an aviation culture and that has changed.
The manufacturers put together a community called UNITE or GROUP, which is the UAS National Industry to work together to help promote getting UAS into the national airspace and to speak as one voice to provide positive influence for the industry. Our goal was to, by 2012, create an environment that supported a viable unmanned aircraft market for public use and civil UA applications that routinely access the NAS. As manufacturers, we do not have access. There’s a certification process as well. Then there’s the third leg of this stool, which is the procedural, and that’s the operational constraints. Right now, the operations are constrained in the COA through a public agency or a government agency for our use. But again, as U.S. manufacturers, we have no way to access airspace on our own. We also need test ranges for UAS development outside of restricted airspace. It’s tough to get restricted airspace access for a number of reasons. One is that the military has limited airspace for themselves to us, so if you’re coming and saying, I have a commercial interest to fly this, you can get to it after you’ve gone through a lot of red tape, paperwork and get in the queue. It is very tough; we really need that to compete not only in the U.S., but also internationally because the competitors overseas have access to airspace that’s easier than we have.
John Appleby, Program Manager, Borders and Maritime Security Division, Science and Technology Directorate, Department of Homeland Security
It’s very focused here at DHS on airspace access for the airplanes that we already have been flying for several years. But there are a lot of broader needs potentially in the near future concerning UASs.
‘It’s very focused here at DHS on airspace access for the airplanes that we already have been flying. But there are of broader needs in the future concerning UASs.’
—John Appleby, Department of Homeland Security
DHS Customs and Border Protection flies six Reapers today, four along the Southwest border, one in the Northern border and one in the Southeast Border. The problem we have is that we believe the fleet is growing slowly. There are probably a few airplanes to be added in the coming years, potentially many airplanes through a period of years. It’s cost driven. But these airplanes are helping with border security and air surveillance specifically along with many piloted aircrafts, large and small.
We’ll have to get there in steps, and the way we have approached it here within S&T and DHS is to try and parallel with the ongoing process of gaining more access to the NAS by the existing COA process is to develop a modeling and simulation program at MIT Lincoln Lab, which will, we believe, help in building any safety case to be presented to FAA ultimately for greater use of UAS aircraft.
The modeling and simulation program at Lincoln Lab is looking to present a modeling and simulation capability for the national airspace. There are three broad components that are modeled in this scheme the national airspace system, the airplane in question, in our case we start with the Reaper. That’s what we have immediate needs for.
So we look at imagining a modeled Reaper flying through the NAS and on board that simulated Reaper, meaning that we’ve simulated its flight performance characteristics in the model, we have an on board sense and avoid system that’s also modeled.
Edgar Waggoner, Director of the Integrated Systems Research Program, NASA
Aviation touches almost all of the general public, but also has a huge impact on the U.S. economy. UASs are poised to further enhance the industry’s impact on the economy.
The integrated systems research program at NASA was established within the Aeronautics Research Mission Directorate to conduct research at an integrated systems level. The UAS and the NAS project is a five-year focused project looking at systems level research and demonstrations of various concepts and technologies that we hope will be used to enable the development and certification of safe and routine operations of unmanned systems in the NAS.
There are five specific subprojects that make up the UAS in the NAS project separation insurance, human systems integration, communication, certification and integrated testing and evaluations project. The guiding vision for this work is a global transportation system, which will allow routine access for all classes of unmanned aircraft systems. The mission and the goal are tied closely together in addressing key barrier problems and contributing capabilities to reduce these technical barriers related to both the safety and operational challenges associated with routine UAS access.
‘UASs are poised to further enhance the industry’s impact on the economy.’
—Edgar Waggoner, NASA
Under the separation assurance subproject, we’ll be assessing NextGen-type aircraft-to-aircraft separation assurance concepts and then how we’ll conflict detection and resolution algorithms apply to UASs. This will include evaluations of different types of responsibilities for maintaining separation. We’ll be looking at a concept where a remote pilot is responsible for staying away from other aircraft, a concept in which the air vehicle autonomously separates itself from other aircraft and then a more traditional concept where you have an air traffic controller still retaining the responsibility for separation. The challenge here will be how do you deal with the very different performance characteristics of all these different classes of UASs, and particularly in comparison to manned aircraft, and then in the delay or the latency of execution of a maneuver because the pilot is remote from the aircraft.
The second subproject is the communications subproject, and we’ll be developing data and rationale to obtain the appropriate frequencies spectrum. The frequency spectrum allocations to enable safe and efficient operations of UAS are key issues. We’ll be developing and validating candidate UAS secure, safety-critical command and control system test equipment that complies with national and international frequency regulations, ICAO standards, and FAA and RTCA minimum operational performance standards and minimum aviation system performance standards. We’ll be performing analysis to support recommendations for the integration of safety-critical command and control systems and air traffic control communications to ensure both safe and efficient operations.
The third subproject is human systems integration. We’ll be developing a research test bed and database that will provide data and proof of concepts for ground control station operations for UASs. Output of this subproject will be a body of work where we’ll be coordinating with standards organizations to develop human factors guidelines for ground control station operations in the NAS.
The certification sub-element will be defining a UAS classification schema and approach to determining air-worthiness requirements that are applicable to UAS avionics and also providing hazard and risk-related-type data to support development of type design criteria and best development practices.
Our fifth subproject is integrated test and evaluation. The technologies developed will be validated through a series of both fast time simulations and high fidelity human in the loop simulations and, where appropriate, integrated flight tests in a relevant test environment.
The technical approach will consist of two phases, and the initial phase will be focused on laying the foundation. Key deliverables will include contributions to a national roadmap. In the second phase, some of the key deliverables will shift towards maturing these research capabilities and integrating them at a systems level through various simulations and flight tests. This work will be coordinated with our government partners and industry to ensure the efforts are complimentary to other work being done in the community.