UPDATE 1-EU aims to straighten air routes to cut CO2

(Adds airline reaction)

By Pete Harrison

BRUSSELS, June 25 (Reuters) - The European Commission launched a plan to straighten out aviation routes on Wednesday to cut fuel costs and carbon dioxide emissions growth from increasing numbers of aircraft.

The EU has set itself the goal of cutting CO2 emissions by a fifth by 2020 compared with 1990, aiming to lead by example at global climate talks next year with other big emitters such as China, India and the United States.

Airlines are responsible for about 3 percent of Europe's CO2 output and traffic is expected to double by 2020.

Aircraft waste millions of tonnes of fuel as they zig-zag their way between national airspaces in the 27-nation bloc.

"Look at the flight paths -- it's ridiculous," European Transport Commissioner Antonio Tajani told reporters. "Look at the costs in terms of pollution and delays."

Simplifying the 27 airspaces to just nine is seen as a quick way of cutting fuel costs, curbing emissions growth and maintaining safety in ever more crowded skies.

The Single European Sky II package builds on a 2004 proposal that ran into opposition from EU countries over several issues including reluctance to give up national control over air space.