Excerpt from article at link:

http://www.newscientist.com/channel/...o-problem.html

Even if the industry gets its act together in time for the 2011
conference, competition for the desired frequencies - probably between
3 and 10 gigahertz - will be fierce, as burgeoning wireless services
demand their share, says Bruno Esposito of rival Paris-based trade
group Euro UAV, which includes major European aerospace companies such
as EADS, the owner of Airbus. "Telecoms firms are not going to let
bandwidth that they have paid billions for go easily to us," he says.

Some UAVs have been allowed to perform short experimental flights in
civil airspace, but only under very strict conditions. "Each is done
under piles of exemptions to air regulations that take a very long
time to negotiate," says Ian Poll of Cranfield Aerospace in Bedford,
UK. This summer, the Los Angeles county sheriff's department was
forbidden from flying its small police surveillance UAVs because of
the risk to other air traffic. What's more, every time the US
government launches a UAV to patrol the Mexican border in a bid to
prevent illegal immigration, civil traffic is banned over hundreds of
square kilometres.

So if UAVs are to mingle safely with other civilian aircraft, the
industry needs to develop a safe, standardised collision avoidance
system. This is complicated because aviation regulators demand that if
UAVs are to have access to civil airspace, they must be "equivalent"
in every way to regular planes. For instance, when an air-traffic
controller needs to talk to a UAV's remote pilot, the radio link
should work in the same way as it does for an aircraft with an onboard
pilot - the controller must be able to talk to the remote pilot as if
they were sitting in the UAV, rather than having to be manually
patched through by a radio operator.

Similarly, a UAV on a collision course with another aircraft must
behave as if it had a pilot on board. In such situations, conventional
pilots obey an evasive-action order from an onboard "traffic collision
alerting system" (TCAS). Ultimately UAVs will probably respond
automatically to these orders. The problem for now is that aviation
regulators have yet to define precisely what they mean by
"equivalent", so UAV makers are not yet willing to commit themselves
to developing collision-avoidance technology.

There will be some point in the future when we all have
sense-and-avoid technology in our UAVs," says Ed Walby of Northrop
Grumman in San Diego, maker of the city-bus-sized Global Hawk military
UAV. "It's simply an issue of waiting for the policy." The next
version of Global Hawk, dubbed the Block 20, for example, will be
fitted with TCAS, Walby says. This will allow a remote pilot to take
evasive action to avoid a collision, but the system will not work
automatically until the term "equivalent" is defined.

In the UK, the government-backed plans for civilian UAVs to be flying
routinely by 2010 are likely to be held up by this lack of a
collision-avoidance system. The project is aiming to develop a
simulated system by 2008, but that will not leave enough time for it
to be developed and in use by 2010. "It's fair to say that we are not
as far along as we would like," says Bryan Edmonson, a technologist
with Flight Refuelling of Wimborne Minster in Dorset, UK, and a member
of the project's steering board.

On the brighter side, last week the UN's International Civil Aviation
Organization, based in Montreal, Canada, said its navigation experts
would meet in early 2007 to consider regulations for UAVs in civil
airspace. That could be a step towards internationally agreed rules
for how UAVs should operate.

Even if the UN body makes rapid progress, however, it will be
meaningless unless the industry can obtain the necessary frequencies
to control the planes and feed images and other sensor data back to
base, says Bowker. "The lack of robust, secure radio spectrum is a
show-stopper."

Some experts are even more pessimistic. These problems mean civil UAVs
may not have a future at all, a recent conference at the Royal
Aeronautical Society in London heard. One aerospace executive, who
asked to remain anonymous, believes UAVs will never fly in civilian
airspace. "It's something the industry wants badly, but the risks are
too high and the issues too complex."