SHANGHAI -- A Chinese airline promised to improve its pilots' English-language skills after one of its planes took off from a Japanese airport without authorization.

In the incident Monday, air traffic controllers at Osaka's Kansai International Airport ordered the China Eastern Airlines jet to taxi to a runway and wait for further instructions. But they were shocked when the aircraft, which was carrying 245 passengers, took off.

The airline landed safely at its Shanghai destination later in the day.

China Eastern said it would cooperate with Japanese investigators, and hinted that a language problem may have been the cause of the incident, the state-run China Daily newspaper reported Thursday. English is the mandated language for aviation.

The airline said it would "further improve the English communication skills of its crew to assure flight safety," the report said.

This week's incident follows a bizarre case from August, reported by The Wall Street Journal, in which private Chinese airline Juneyao was temporarily banned from hiring foreign pilots after a Korean pilot on one of its flights refused to give way to a Qatar Airways jet that had issued a "mayday" call and requested immediate permission to land.

In that incident, the Juneyao pilot ignored six orders from the control tower to first allow the

Qatari jet to land. Both aircraft eventually touched down safely.

China's civil aviation authority said in 2007 that less than one-tenth of its pilots met international standards for English proficiency.