Shedding pounds isn't just a preoccupation of dieters,
it is a prime concern for aircraft builders too. In a bid to reduce
weight to the minimum they are considering the controversial move
of getting rid of the huge quantity of copper wiring used in modern
planes and replacing it with a series of wireless
networks.
Users of Wi-Fi may be forgiven for wondering if this is wise.
Reliability is not one of the defining characteristics of existing
wireless networks, so employing them to operate a plane's flight
systems might seem a little risky. But if they can be made robust,
such "fly-by-wireless" networks have the potential to improve
reliability and possibly even make flying a little less
environmentally damaging.
Though fly-by-wireless is the ultimate aim, the first step along
the way is likely to be the introduction of wireless sensors.
Aircraft are already fitted with numerous sensors that provide
information about the plane's performance, such as how efficiently
engines are operating. Data from the sensors can also be recorded
and used to alert maintenance crews on the ground to any abnormal
events.
The principal motivation for getting rid of the copper cabling
that is now used to collect data from these monitors comes down to
weight, "which on aircraft comes at a premium", says Mark Begbie,
director of the Institute for System Level Integration, a
collaboration of engineers at UK universities in Edinburgh, Glasgow
and Lancaster.
As the complexity of aircraft and their engines has grown, so
too has the amount of wiring needed to monitor, maintain and
control them. The trend is towards increasing the number of sensors
in aircraft in order to improve the ways they are maintained,
Begbie says.
This presents a challenge: how to prevent this ever increasing
complexity from making aircraft heavier. Modern airliners already
have several kilometres of wiring, says Myles Taylor at GE Aviation
Systems, a maker of aircraft infrastructure in Bishop's Cleeve,
Gloucestershire, in the UK. If you can replace this with a wireless
system, you not only considerably reduce the weight of the aircraft
and the amount of fuel it uses, but also make it easier to build
and maintain.
The ability to mount sensors on many more parts of the airframe
and engines could lead to design improvements in future aircraft
that will cut their weight by as much as 15 per cent, says Roger
Hazelden of British engineering consultants TRW Conekt. That could
equate to a 12 per cent reduction in fuel consumption. Operating
the plane wirelessly should cut the weight even further.
Any wireless network built into aircraft will have to be
resistant to interference, not least from passengers' Wi-Fi devices
and cellphones, and environmental effects such as lightning
strikes. It will also have to contend with the possibility of a
deliberate attack by hackers.
This should not pose insuperable problems, according to Tom
Anderson, director of the Centre for Software Reliability, at
Newcastle University in the UK. He says similar concerns were
raised when plane-makers started to replace mechanical flight
controls with digital "fly-by-wire" control systems, but proved
unfounded.
Peter Mellor, formerly a researcher at the Centre for Software
Reliability at City University in London, points to an as yet
unsolved problem that could affect even the most interference and
hacking-resistant wireless network. A strong radio signal could be
used to jam the network by swamping its wireless communications,
Mellor says. "You would effectively have a denial of service
attack, which would be a very unfortunate thing to have on an
aircraft."
We should not let the poor design of existing wireless networks
put us off, Anderson says. Wireless doesn't have to be any less
secure than wired networks, and is immune to some of the problems
that can befall cabling, such as broken connections or short
circuits.
Before any wireless system is implemented it will have to meet
rigorous criteria set by bodies like the International Civil
Aviation Organization. A working group of the International
Telecommunications Union is currently examining the prospects for
wireless avionics systems.