Action on wind farm radar threat to aircraft

26.5.2009   (Times)

by David Robertson

The body that monitors UK airspace is seeking a solution to the potentially disastrous
problem of commercial and military aircraft disappearing in radar blackout zones
caused by wind farms.

National Air Traffic Services (Nats) has asked Raytheon, the American defence
company, to design the world’s first system for allowing radar to see through
wind farm interference.

The cost of the £5 million project is expected to be picked up by the wind energy

Wind farm turbines create a Doppler effect as they turn, which shows up on radar
screens.   As the area and number of these wind farms has increased, the number
of radar blackout zones has also risen.   Aircraft passing through the area can
disappear in the blackout and air traffic controllers can lose their exact position

The Royal Air Force is concerned that enemy bombers or other aircraft could hide
behind interference from offshore wind farms and approach Britain undetected.

A Nats spokesman said: "We have a duty to safeguard our operations, so in the
past we have objected to the development of a number of wind farms that threaten
aircraft safety.   We need a system that can eliminate this problem."

Raytheon has been asked to create a software system that will filter out the
wind farm noise from other radar signals.   This will effectively allow air traffic
controllers to see through the wind farms. The company, which is the largest manufacturer
of radar systems in the world, hopes to complete the project by the end of next
year.   Once completed, it will also be deployed in the Netherlands.

Andy Zogg, vice-president of command and control systems at Raytheon, said: "As
the number of wind farms grows, there are more and more of these radar black holes.
They show up as clutter on the radar screen and the concern is that aircraft approaching
from behind the turbines or flying over them cannot be seen."

Brian Smith, general manager of Raytheon Canada, said: "Our work will be to develop
the algorithms that allow us to discriminate between turbines and aircraft. It
is called clutter erasure."

The Government has identified wind power as a key to reducing reliance on carbon
dioxide producing energy sources.

Europe’s largest onshore wind farm opened last week at Whitelee in Scotland.
The 140 turbines cover an area of 55 square kilometres and are each 110 metres
high. The wind farm will generate enough electricity to power 250,000 homes.