Source:
https://scmp.com/article/464435/hijack-attempt-air-china-jet

Hijack attempt on Air China jet

Threat by a man with a history of mental illness forces Zhengzhou emergency landing

A 32-year-old man yesterday forced the emergency landing of an Air China passenger jet in Zhengzhou after claiming that a friend would spray acid in the plane if it did not take him to South Korea.