China Southern Airlines signed a deal on Tuesday to buy 10 Boeing 787 aircraft for about $1.2 billion, state television reported. China Central Television did not give further details of Tuesday's deal, signed in Guangzhou, capital of the southern Chinese province of Guangdong. Early this month, China Southern, the country's largest carrier by fleet size, purchased three 787 planes from Boeing Co. as part of a larger deal involving four airlines and a total of 42 787s. China Southern's shares skidded on Monday after it reported worse-than-expected first half results on tough price competition and high fuel costs.