China's three major airline conglom erates pledged for the first time to cooperate on aircraft maintenance Tuesday at the 7th Zhuhai Air Show held in the southern coastal Zhuhai, Guangdong province.

Parents of China Southern Airlines, Air China and China Eastern Airlines singed a Letter of Intent on the cooperation at the air show.

They vowed to cooperate in airline maintenance, aviation utilities sharing, in-depth overhaul and maintenance training so as to improve m aintenance capabilities and efficiency and reduce costs.

Maintenance cost makes up 10-17 percent of the total cost of airlin e operators, said Heli, vice president of Air China.

However, it is hard to predict how much the cooperation can trim th e cost as the companies only signed the Letter of Intent.

Details on the cooperation will be discussed later in accordance wi th the Letter of Intent.

Cooperation in maintenance is relatively easy in the aviation sector, said He.

As airline companies are scourged by recent economic crisis, concer ted efforts among major airlines mark a strategic move to control cost and mitigate the effects of crisis.