The Lin Biao incident (Chinese: 九一三事件; lit. 'September 13 Incident') was an aircraft accident at 2:30 a.m. on 13 September 1971 involving Lin Biao, the sole Vice Chairman of the Chinese Communist Party. Everyone on board a PLAAF Hawker Siddeley Trident, including Lin and several members of his family, died when the aircraft impacted Mongolian terrain.
As Vice Chairman, Lin Biao had been the official heir to Chairman Mao Zedong since 1966. From 1970, a rift developed between on one side Lin and his power base in the Army and Politburo, and on the other side, Mao, his allies Jiang Qing and Zhou Enlai, and their PLA factions. Issues included Lin's growing power in the PLA and his prominent role in Mao's cult of personality, which Mao had criticized as excessive. The crash was a key event at the midpoint of the ten-year Cultural Revolution, following which the Gang of Four gained prominence.