WIND turbines could be wrongly identified as aircraft by North-East airports, experts fear.

The Ministry of Defence has ordered a series of test flights to assess the extent to which the turbines' rotating blades can be wrongly identified by airport radar as unidentified aircraft.

A Teesside air safety company, Flight Precision Ltd (FPL), which is based at DurhamTeesValley Airport, is using the latest technology in measuring equipment to carry out crucial safety tests.

The North-East is already at the forefront in the use of wind power. Last month, a report recommended that up to 13,000 turbines providing renewable energy could be sited off the region's coastline.

Andy Radforth, sales and marketing manager at FPL, said radar could mistake the turbines as aircraft coming into view.

He said: The knee-jerk response to that is to say that if radar computer systems and operators know where a windfarm is, then they can simply ignore the return it leaves 'painted' on their screens.

"The problem is that a real aircraft, legitimately flying near a windfarm, might be ignored as being part of the same radar return, until suddenly it is far enough away from the turbines for it to be seen it as a separate object.

"By then it might well pose a very real danger to other aircraft."

One solution to the problem that has been suggested is for aircraft to be routed by air traffic controllers so they are always more than a minimum of five nautical miles away from a wind farm.

But because of the number of wind farms, this has been dismissed as it would prove impossible for planes to land safely at many British airports.

Mr Radforth said that evidence appeared to show that wind turbines created a shadow the same shape as that formed behind a sizeable hill, within which radar performance is seriously affected.

He said: "With the sensitive position measuring instruments in our aircraft, we can fly into these shadow areas and measure just how accurately and predictably airport radars can track us in all the various conditions.

"The data obtained, hopefully, may help in the development of new systems to allow all aircraft to fly safely near wind turbines."

A Teesside Airport spokewoman said: "This work will prove extremely important in the ongoing discussions relating to the potential effects of wind farms on airport radar systems."