YORK scientists are helping RAF pilots avoid one of their oldest enemies - birds.

Collisions with birds are estimated to cost the air force some £13 million a year.

Larger creatures can wreck engines, smash cockpits and even kill pilots.

But scientists from the Central Science Laboratory at Sand Hutton near York have been working with the RAF to tackle the problem.

They have been drawing up an ornithological map of Britain to help pilots plan routes which avoid large concentrations of birds.

And in a second project, they have been working on a computer program to help aircraft designers introduce safety features to strengthen vulnerable areas of plane structures.

The map has been drawn up by the Ministry of Agriculture agency using its own data, plus information supplied by organisations such as the British Trust for Ornithology and the Wildfowl and Wetlands Trust, says Richard Budgey, who has day-to-day responsibility for the CSL project.

The idea is that, before a mission, a pilot will consult the map data base to discover where there are large concentrations of birds, and then pick a route where fewer birds are anticipated. The map has been undergoing trials at an East Anglian air base for some six months to see if it can be used across the country or requires modification.

Meanwhile, to help avoid disaster when planes do strike a bird, the computer program is being devised to make military and civilian aircraft stronger in their most vulnerable areas.

The program allows a "virtual" aircraft to be flown through "virtual" flocks to see how it will be affected.

Species of birds most commonly struck were filmed on video by two cameras three metres apart to produce a three-dimensional image to be used in the program.

Distances and angles between birds were worked out for different species, so that the scientists could work out how many birds would hit planes and where.

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