Just as in the U.S. there is considerable interest in Europe in developing a solution to the sense-and-avoid problem for unmanned aircraft. A number of different programs are running concurrently under different national, international and industrial consortia, and while several have clocked up significant hours of flight test in surrogate or testbed aircraft, none have as yet flown on board an unmanned platform.
The European Defense Agency funds the MIDCAS (mid-air collision avoidance system) project, which began in 2009 and is due to reach completion this year. The 11-member industrial consortium is drawn from five nations (Sweden, Italy, Germany, Spain and France) and is led by Saab, but detail on progress of the €50 million program is scant.
Selex ES (Outdoor Exhibit 1), which is part of MIDCAS, is also involved in another project in the UK in partnership with the company 2Excel Aviation. 2Excel offers plug-and-play flight-test facilities to industry on board two Piper Navajos from its base at Sywell Aerodrome in Northamptonshire.
Over several years, 2Excel has flown the two aircraft on near-collision headings, and has built up an extensive database of information about how far away, and in what conditions, the trained human eye can spot an inbound threat. Then, by linking a number of off-the-shelf EO cameras distributed in forward-facing locations on the airframe, and with an on-board algorithm designed by Selex, subsequent flights have demonstrated that the system is capable of detecting another aircraft on a potential collision course at longer range and earlier than a human pilot. The system, which is called Sense To Avoid, has been demonstrated to the UK’s regulator, the CAA, and to a delegation from the FAA. Further test flights are planned for later this year.
Jetstreaming Ahead
Probably the highest profile, and arguably the furthest advanced, European sense-and-avoid program has been conducted as part of the UK’s ASTRAEA (autonomous systems technology related airborne evaluation and assessment) program. Although ASTRAEA is not focused solely on sense-and-avoid–the industrial, academic and governmental consortium is looking more broadly at technologies and regulations required to facilitate routine flights of UASs in unrestricted civil airspace–the project has tested a sense-and-avoid system extensively.
Electro-optical sensors have been installed on a BAE Systems-owned and -operated twin-turboprop Jetstream aircraft and, using an algorithm developed by Thales, the ASTRAEA sense-and-avoid system has been flown over the Irish Sea. In keeping with the ASTRAEA methodology, though, the flights did not just test the subsystem, but also looked at how an aircraft equipped with it might be integrated into civilian airspace.
The Jetstream had a pilot on board, who operated the aircraft in takeoff, landing and other selected phases of the flight, and was ready to take over in the event of a communications failure or any other emergency situation. But for extensive periods the aircraft was under the control of BAE test pilot Bob Fraser (who also made the first flight of the company’s Taranis UAV last year), who was in a cockpit on the ground.
The flights saw Fraser liaising with air-traffic controllers, including during handovers from one controller to another, and making collision-avoidance maneuvers in much the same way as he would have done had he been on board the aircraft. “The way we’ve been flying over the Irish Sea is that the system will offer to the man on the ground notification of conflict and suggest an avoiding action,” Fraser told delegates to the Royal Aeronautical Society’s RPAS Today conference in London last month. “He can either select that or reject it, and if you keep rejecting it, it will get to a minimum closing angle and then take action itself. But it means that if you’re in controlled airspace you can reject the initial action, have a chat with ATC, get clearance for that turn and then accept the turn. So it’s just a matter of which level of airspace you’re in that will dictate what action the pilot on the ground actually takes.”
The ASTRAEA program is currently in its third phase (known as ASTRAEA 3A), which is concentrating on regulatory and certification issues. ASTRAEA’s program director, Lambert Dopping-Hepenstal, told the RAeS conference that an application for funding to the UK government’s Aerospace Technology Institute is currently in preparation to facilitate a fourth phase (3B). Under the terms of the ASTRAEA program, half the funding comes from government and the remainder from the industrial partners.
“ASTRAEA 3B will be trying to validate and verify the work we’ve done to date,” Dopping-Hepenstal said. “[3B will be concerned with] continuing the regulation and certification work from 3A, but particularly getting into some significant capability demonstrations and beginning to stretch the points and challenge the use of the technology through a whole series of increasingly challenging flight trials.” If funding is approved, ASTRAEA 3B is scheduled to run to 2018.
