The UAV community has visions of using nonsegregated airspace, i.e., airspace used by manned aircraft. But this is a dream since, at present, unmanned aircraft mainly have to use airspace that is segregated spatially–set aside for military use, for example–or in time via temporary flight restrictions. With segregated airspace in ever shorter supply, the UAV fraternity wants access to nonsegregated airspace. In short, it wants to be able to "file and fly," just like manned aircraft.

In Europe the UAV issue is particularly acute because the already dense traffic over its core central region is likely to double by 2020, according to Holger Matthiessen, an air traffic management (ATM) expert with Eurocontrol’s Central Flow Management unit. (In the United States a 50 percent traffic hike is projected by 2017.) Eurocontrol and other European interests are considering how to manage a transition that would permit shared use of national and international airspace without making UAV operation economically impractical.

The challenge is heightened by the diverse nature of UAVs. Vehicles weigh anything from grams to tons. They can be piloted from the ground or fly more or less autonomously. They can be rotary-, fixed- or flapping-wing in design; military, civil government or commercial in application. They can fly alone or in swarms and can operate at altitudes from 500 to 50,000 feet and at airspeeds from 25 to 500 knots. By 2020 we might see large unmanned cargo jets crossing the Atlantic, surmised Matthiessen at the Avionics ’06 conference held in Amsterdam. Progression from cargo to passenger transports might not then be far behind.

Another complicating factor is the remoteness of the ground-based pilot–or the programming intelligence, in the case of autonomously operating vehicles–from the aircraft. This means that regulatory and certification bodies cannot consider a UAV as a flight vehicle in isolation. The European Aviation Safety Agency (EASA) sees a UAV as a total system and proposes, in a draft policy, that certification should apply to the control stations (if any), the communications links and to any launch and recovery elements, as well as to the vehicle itself.

Successful transition into general airspace requires technological solutions accompanied by a regulatory and certification infrastructure sufficiently defined to guide the efforts of avionics manufacturers and integrators. Technical development is still needed in certain key areas, notably collision avoidance, where a UAV-specific sense-and-avoid capability is required, and in achieving a level of avionics integrity, or trustworthiness, equivalent to that on manned aircraft. Using equipment already available for manned aircraft is often a nonstarter due to factors such as weight, bulk and expense and because of different functionality dictated by the lack of an onboard pilot.

Pressure

Pressure is growing from both the civil and military UAV sectors, which see airspace access as key to unlocking a vastly expanded market and increased operational flexibility, respectively. Civilian uses in particular could grow rapidly, ranging from crop spraying to Earth observation and from forest fire management to telecommunications relay. According to a study by the consultancy Frost & Sullivan, the European civil UAV market will be worth ?100 million ($127 million) annually by 2010 and ?270 million ($344 million) by 2015. Speakers at Avionics ’06 pointed out parallels between the situation now with unmanned aircraft and that, circa 1920, when military use of manned aircraft, which had been predominant, was about to be eclipsed by a surge in civilian use.

For its part, the military wants access because it is running out of segregated airspace, which in any case does not fully meet its needs. Both civil and military camps accept that the rules for coexistence between manned and unmanned aircraft will have to be established within existing national and international ATM safety parameters. One Eurocontrol military spokesman puts it succinctly. According to Wing Cmdr. Mike Strong of the UK’s Royal Air Force, a member of Eurocontrol’s UAV operational air traffic (OAT) task force, "UAVs should not increase risk to other airspace users and should not deny airspace to them."

Strong adds that the ATM regulations and procedures for UAVs should mirror, as closely as possible, those applicable to manned aircraft, with air traffic controllers noticing no handling differences between manned and unmanned aircraft. Only in special circumstances, such as loss of a control data link, would there be any significant differences in ATM procedures.

Eurocontrol set up its OAT task force in 2004 in response to requests from military interests. Made up of military and civilian experts with experience in the ATM aspects of UAV operations, the task force was charged with developing draft specifications for UAV airspace usage which individual states might then incorporate into their national regulations. Though there will be no obligation for states to do this, Eurocontrol suggests that the need to harmonize practices across Europe provides a strong incentive. Currently, some 33 standalone ATM specifications are undergoing final safety assurance processing and review, and should be ready to present to Eurocontrol’s Provisional Council late this year. Once they have been fully approved and dovetailed with policies on other aspects of UAV operation, they will be published.

Sense and Avoid

To avoid conflicts in controlled airspace between unmanned and manned aircraft operating under instrument flight rules (IFR), OAT favors separations at least equal to those applied now to manned aircraft in the various classes of airspace. Where there is no air traffic control and responsibility for collision avoidance therefore rests with pilots, a minimum separation of 500 feet (150 m) in all directions has been proposed. Lacking a pair of eyes to ensure this, the UAV would require an equipment substitute.

One proposal is to fit a modified form of airborne collision avoidance system (ACAS). A "standard" ACAS would not suffice since its operation is predicated on having a pilot on board. In the unmanned situation, greater functionality is required of a sense-and-avoid system, and further research is needed to achieve a practical all-weather solution. Researchers are exploring substitute vision technology, based on forward-looking optical, video, radar or infrared (IR) sensing, or a fused-sensor combination. Alternatively, collision avoidance could be based on transponder returns–automatic dependent surveillance-broadcast (ADS-B), for instance, though this works only for cooperative targets, those equipped with working transponders.

Alex Hendriks, head of the Airspace Flow Management and Navigation Business division at Eurocontrol, agrees with his military colleagues’ assessment of technology priorities. As he tells Avionics Magazine, "We’re not yet sure how compatible UAV sense-and-avoid can be with see-and-avoid [on manned aircraft]. Much will depend on the equipage of GA [general aviation] aircraft; in a few years’ time they may all have transponders."

Another potential roadblock, he explains, is the issue of obtaining the frequency allocation for the necessary UAV control data link. If a successful bid for spectrum is not lodged at the World Radio Conference (WRC) in 2007, the next realistic opportunity to present a bid to the WRC comes in 2010. Working papers would have to be presented in advance, probably in 2008-2009. "We’ll be ready for that," says Hendriks. "We hope that having the combined weight of the FAA and Eurocontrol, plus the fact that the two agencies chair key policy making groups, will make a difference." Eurocontrol liaises closely with the FAA, so that North America and Europe can move forward more or less together on UAV airspace issues. The two agencies have a longstanding memorandum of cooperation, dating from the mid-1990s.

Certification Basis

Development of UAV avionics has been constrained by the lack of specific regulations and standards under which certification can be achieved. This gap, however, is in the process of being filled.

On the civil side, the European Organization for Civil Aviation Equipment (EUROCAE) has established (in coordination with RTCA) working group 73, WG73, to prepare performance specifications for UAV systems. These will eventually appear as minimum operational performance specifications (MOPS) and minimum aviation system performance specifications (MASPS). The cross-Atlantic collaboration should promote early-stage harmonization, which would be further strengthened by feeding in the results from the U.S. Access 5 UAV/airspace integration initiative. At the inaugural WG73 meeting in Brussels, the more than 150 participants agreed that Eurocontrol should chair the working group and FAA take the sub-chair.

The creation of WG73 was encouraged by UVS International (UVSI), the European nonprofit association representing the global UAV system community, which was dismayed by the pace of airspace integration work. Industry, research, regulation and air navigation system provider interests from inside and outside Europe are represented in the working group. According to UVSI president, Peter van Blyenburgh, the meeting highlighted the critical importance of sense-and-avoid, a topic to which one of the first WG73 subgroups to be formed will be dedicated. This subgroup will be tasked with defining operational requirements for sense-and-avoid.

"This is not a minor task," van Blyenburgh comments, "especially when standardization bodies and regulators are still struggling to define exactly what a UAV is and even if `UAV’ is the most appropriate designation."

This year is also significant for EASA and its UAV-related activities. The agency, successor to the Joint Aviation Authority (JAA) and equivalent to the certification part of the FAA, expects to issue a formal policy for UAV type certification this summer. This is a crucial step in its plan to have a regulatory underpinning for UAV flights in nonsegregated airspace in place by 2009. It follows the issuing of an interim advanced notice of proposed amendment (A-NPA), a signal that definitive regulation will take place soon, probably starting in the summer of 2007.

According to Yves Morier, head of EASA’s Product Safety Unit Rulemaking Directorate, the A-NPA also serves as a vehicle for "putting thoughts on the table" and encouraging dialogue with other agencies around the world. Morier believes that cooperation between the FAA, EASA and Eurocontrol provides a common core around which international harmonization can take place. The FAA agrees, its associate administrator for aviation safety, Nick Sabatini, having described the A-NPA as a "strawman," or early stage document, to help shape trans-Atlantic thinking.

EASA suggests that air vehicles weighing more than 330 pounds (150 kg) at takeoff can be certificated using airworthiness codes already defined for manned aircraft and within existing Part 21 regulations, adapted where necessary. Smaller UAVs would be subject to the regulations of individual states. Regulations should be framed to protect the safety of all airspace users, but also, EASA insists in its draft policy, the safety of people on the ground. However, the agency is not yet sure whether consideration of the latter should be based on impact energy measures developed specifically for UAVs or whether the issue can be addressed by extending the weight categories that exist for manned aircraft.

In an apparent recognition that the task of coordinating the introduction of routine UAV operations into Europe’s controlled airspace may be too large for the still-infant agency, EASA recently called for the creation of another body to undertake that task. It is not clear if and how EASA’s call will be answered, though more information may emerge as a result of a UAV-related ICAO meeting that was planned for late spring.

The U.S. Access 5 action plan for airspace integration, promoted by a UAV National Industry Team (UNITE), ended in February 2006, following the withdrawal of NASA funding support. However, some of the program’s momentum might be picked up by other agencies, including the U.S. Department of Defense and Department of Homeland Security. Europe, though lacking a directly comparable program, is working at the government level to formulate a concerted requirements document, non-military in this case. The pan-European program will identify potential applications and define a range of operating scenarios, so that policy makers and industry can then home in on the most promising. Industry will have a clear input–chiefly via UVSI, which is acting as the program’s coordinator–to what amounts to a consolidated action plan. A first iteration of this plan is expected by the spring of 2007, to be followed by a definitive version early the following year.

Van Blyenburgh believes that the resulting plan will be a significant step in the right direction. "Europe certainly needs more teaming arrangements," he told Avionics ’06 delegates. "Too many nations are spending money developing solutions that may be applicable only within the boundaries of those nations."

The UVSI president goes beyond this, however, arguing that UAV systems are a global phenomenon, requiring global solutions. "In Europe we [UVSI] have started a global access initiative, one purpose of which is to combine all the information coming from individual nations into a major multinational database which would be made available to all. There’s no point in any country acting in splendid isolation on this."

Van Blyenburgh’s last remark may be a sideswipe at, among other suspects, the UK, whose Department of Trade and Industry did not conspicuously seek to dovetail with other European initiatives in setting up its Autonomous Systems Technology Related Airborne Evaluation and Assessment (ASTRAEA) program. This initiative, aimed at normalizing UAV operations in UK airspace, has ?32 million ($60 million) in funding for an initial three years of activity, starting January 2006. The first six months of the program, which involves 13 government and industry entities, are being spent analyzing relevant technologies, including sense-and-avoid, robust communications and reliability-enhancing health monitoring systems. The focus is on technologies that can be matured in 18 months, so that a prototype ASTRAEA air traffic integration architecture can be developed. This would be tested in flight trials scheduled to take place in the final year of the program, from January 2008.

ASTRAEA will gain from the presence of the new ParcAberporth UAV center of excellence which has been set up, with official support, in west Wales. The center boasts comprehensive facilities for testing and flight trialing UAV systems. In April 2006 it hosted a series of technology demonstrations, organized by the UK research organization, QinetiQ. Technologies featured included sense-and-avoid, data link security and radio frequency spectrum management. The UK started on its own regulatory road a few years ago when the Civil Aviation Authority (CAA) published its CAP 722 set of regulatory guidelines.

The UK is not the only country on the northeastern side of the Atlantic with a significant national program. Others include Belgium, France, Germany, Italy, Switzerland, Sweden and Finland. Countries with UAV activity outside the Europe-U.S. axis must also be brought into the global collaboration loop, van Blyenburgh thinks. He points out that Japan, for example, already has 4,700 licensed operators of over 2,000 commercial UAVs, many of them working in the agricultural sector. Israel is a notable UAV pioneer, while Australia, Canada, Singapore, South Africa, South Korea, Turkey and others have programs, too. All share the desire for expanded airspace access. South Korea acknowledges this in its UAV roadmap, while Australia has adopted Civil Aviation Safety Regulations (CASR) Part 101, Unmanned Aircraft and Rocket Operations. Canada is reported to be interested in joining the U.S./Europe harmonization initiative.

Clearly unrestricted airspace access is a holy grail for UAV system interests since it could unlock a lucrative new market for airframers and suppliers of equipment, particularly avionics. In any case, as Hendriks aptly summarizes, "UAV systems are part of the future–we have to accommodate them."

Success: Not a Given

Success for unmanned air vehicle (UAV) systems in civil-controlled airspace is not a given. Attitudes of the air traffic control (ATC) community, for instance, could be pivotal and, at present, controllers are suspicious. Can UAV systems respond appropriately to ATC instructions, they ask, and can controllers communicate effectively with pilots? What about the latency (delay) of UAV data link systems? Alex Hendriks, head of Eurocontrol’s Airspace Flow Management and Navigation Business division, believes that the concerns of air navigation service providers (ANSPs) can be met over time. He makes the persuasive point that manned transport aircraft routinely fly autonomously now, their pilots acting as system overseers while their charges undertake entire flight segments and descend to just short of touchdown during Category III approaches, all under autonomous guidance.

Meanwhile, some commentators suggest that the need to equal the safety standards of manned aircraft might make UAV systems too expensive to acquire, even though they might promise lower costs over a complete life cycle. Peter van Blyenburgh, president of UVS International (UVSI), begs to differ. “As soon as a technical solution [for sense-and-avoid] becomes available that is acceptable to the regulators, its biggest market may well be civil manned aircraft. The production quantities involved in meeting this, plus the UAV market, will bring down prices.”

Avionics producers hope to reduce costs by leveraging commercial-based systems and components, and by thinking innovatively. An example of the latter is the GuideStar package developed by the Athena Technologies, Warrenton, Va. Athena has addressed the reliability issue by producing a combined sensor/navigation/flight control package that is so compact and inexpensive ($5,000 per system at optimum production rate is quoted) that multiple copies can be integrated, achieving high levels of redundancy. GuideStar utilizes miniature electronics “borrowed” from sectors such as the automotive industry. If Athena succeeds in its aim to have the system certified, albeit on a manned aircraft initially, it could pave the way toward affordable UAV systems. Another encouraging U.S. development was the granting of an experimental certification for General Atomics’ Altair vehicle. It is for one year only and comes with restrictions. But, even so, the Altair can now fly in civil airspace and will, it is hoped, start to increase the comfort level for FAA and others.