Washington (AFP) March 1, 2013Air China signed an agreement Friday to buy 31 Boeing passenger and cargo planes from Boeing, subject to government approval, the Chinese flag carrier said. Air China will purchase 20 Boeing 737-800 aircraft, two Boeing 747-8 aircraft, one Boeing 777-300ER aircraft and its unit Air China Cargo would buy eight Boeing 777 cargo planes, the airline said in a statement. The total value of th Reported by Energy Daily 13 hours ago.