July 23, 1954, a Cathay Pacific Airways DC-4 Skymaster airliner en route from Bangkok to Hong Kong was shot down over the international waters east of San-ya, Hainan, China by two Chinese Liberation Army Air Force's Soviet-made La-11 fighters. Ten on board were killed and eight wounded.
Three days later, at 10:05 a.m., July 26, 1954, two La-11 fighters of PLAAF’s 29th Air Division were downed by US Navy aircraft in an engagement over eastern waters of Hainan. Chinese pilot Zhou Zheng-dong and his wingman were both killed in action. The US State Department protested to the Chinese authorities; however, the statements issued by both sides appeared to be conflicted as to how the incident actually happened.
The relationships among Britain, US, France, and China immediately became rather tense after this incident. Receiving the British protest, Chinese foreign office expressed her regret, indicating that the July 23 incident was caused by mistaken identification. Beijing alleged that the two La-11s were on an escort mission for Eastern bloc vessels and found a big-sized aircraft. They mistook it as a Republic of China Air Force bomber when the ground control asked them to identify the aircraft. PLAAF fighters then took the liberty to open fire and shot down the DC-4. China pointed out that it was an accident and expressed sympathy and condolences to the families of the dead and the wounded and agreed to compensate for the damage done. China later paid an indemnity of 251,400 pounds to Cathay Pacific Airways and 367,000 pounds to the British government.