Saab is breaking new ground with studies of UAVs in an internet-based defence system

Julian Moxon/STOCKHOLM

Sweden's ground-breaking work on internet-based warfare systems has placed it at the forefront of current thinking on potential unmanned air vehicle (UAV) capabilities.

At last year's Farnborough Air Show, Saab Aerospace presented its NetDefense concept, in which all elements of a future fighting force, including weapons, soldiers, sensors and information sources, are accessible through the internet and are, therefore, always connected and easily accessible via secure links.

Key to such concepts is the UAV. "This network leads to a positive engagement with the enemy, and UAVs will be central to reconnaissance, sensing and precision attack in the future," says Saab Aerospace general manager of future technologies Lennart Sindahl.

He adds that the scope of this and other NetDefense programmes "is to be well prepared to discuss with our main customer [the Swedish Government] how to proceed with FMI2020 [the Swedish armed forces' vision of future defence planning requirements up to 2020]".

UAVs are envisaged as providing operational capabilities ranging across the spectrum of warfighting roles. A high-altitude, long-endurance (HALE) UAV equipped with forward-looking radar would carry out damage assessment following an attack, for example, and might call in a point-reconnaissance UAV to carry out a detailed search of a particular area - all without human interference: "The sensor puts information into the database, the attacking weapons get it out," he says.

Sindahl admits this leads to some "interesting thoughts" on how much autonomy UAVs should have: "I see a world where we have one sensor UAV which says, 'I see tanks preparing to fire. If you don't stop me within 10 seconds I'll call in an attack.' We're thinking the way to go is to build focused UAVs that would carry out specific functions," adds Sindahl. "We call them U@Vs since they would be a part of a network."

HALE UAVs would carry out their own data sensing and fusion, taking inputs from whatever sensors, besides their own, are relevant and available on the network. "All we do is give them tasks," says Sindahl. "They will have a lot of autonomy, so there is less need for high-bandwidth communications. So they identify unknown targets by comparing the images they receive with those in the net database. It's no use sending tens of megabits just to show countryside."

Reliability will be a major issue, both to ensure tasks are carried out and to enable UAVs to operate in controlled airspace. This will have to take into account self-monitoring and the possibility of jamming, he says. "We think the civil and military markets will only appear when you have UAVs with the reliability to enable them to fly wherever you want," he adds.

Much of the thinking behind the Swedish company's UAV work is led by Carleric Weiland, Saab Aerospace director of advanced design. He says UAVs "must be permitted to fly freely in unrestricted airspace - the situation at present, whereby they can only fly in such areas after a NOTAM [notice to airmen] is issued a week before, cannot go on much longer".

On autonomy, Weiland says: "We have to solve the issue. Even if there is full autonomy there will have to be someone in charge, to plan, talk to air traffic control [ATC] and so on." He adds: "It could be a grounded pilot or even an ATC controller, who would have the right background to control numbers of vehicles at once."

The operator "only gives commands. He does not control - it's exactly the same function as ATC carries out with manned aircraft today," says Weiland. "I can imagine having a sensor operator who points at a map or picture of what he wants, then the trajectory planner in the aircraft transforms it automatically into a flight plan.

"What we don't know today is to what extent pilots take care of engineering problems in the [manned] aircraft, so during testing of autonomous vehicles there will be crashes and mistakes the causes of which will, with hindsight, seem obvious," Weiland cautions. "That's how air safety has evolved."

He says UAV airworthiness "must be at least the same magnitude as that of civil airliners". Methods of ensuring this could include combinations of: ground- or aircraft-based radar; forward- or side-looking cameras; electronic detection and collision avoidance systems; visual observation from one or more ground sites; and chase aircraft monitoring.

Saab has looked at the current probability of fatal accidents in manned aircraft and come up with an average figure of 0.5 accidents per million flying hours for scheduled flights. But it prefers to look at military aircraft accident probability rates "because they seem to be acceptable to the general public", says Weiland. The accident rate of the Lockheed Martin F-16, for example, which in US Air Force service has averaged 3.5 per 100,000 flying hours over the last 10 years, "may be used as the standard for UAVs", he says.

"A safe and sound strategy should be to start in closed airspace over a closed test range and, step-by-step, open up for usage in unrestricted airspace," Weiland says. This would work as a requirement for total system safety when certification is considered. "We're thinking the Joint Aviation Authorities JAR 23 and JAR 25 standards [covering utility, commuter and large aircraft] could be used as a starter."

Weiland says that current UAV safety levels stand at about an accident every 1,000 flying hours, excluding combat losses: "Things are going to have to improve. If you want to go from 1 accident/1,000h to 1/million there's a lot to do."

Talks are beginning on forming a "Euro UVS" group aimed at bringing the certification authorities together with industry, the hope being that funding can be obtained from the European Commission's Fifth Framework technology acquisition programme.

Source: Flight International