According to Boxun on July 30, 2014, the recent unusual cancellation of the majority of flights between Beijing and Shanghai without advance warning, the military drills over the East China Sea, and the Air Traffic Control’s announcement about a large number of civil aviation flight cancellations on July 30 are all related to Zhou Yongkang’s takedown. Zhou Yongkang was a former Politburo Standing Committee member of the Chinese Communist Party and the former domestic security chief. On July 30, the Central Commission for Discipline Inspection of the CCP announced that Zhou was under investigation for "serious disciplinary violations."
Boxun said that military drills were preparation for deterring the possible bounce back of Zhou Yongkang and his supporters and the large number of civil aircraft cancelations was done in order to prevent officials from fleeing.
Source: Boxun, July 30, 2014