Chinese news agency Xinhua has reported that four recent night flights landing at Dalian Zhoushuizi International Airport, in Liaoning province, had communications between the cockpit and the control tower disturbed by interference from illegal "black radio" stations broadcasting nearby.
The flights were forced to land while the signal of their instrument landing system became unstable because of unknown electromagnetic interference.
Xinhua said that local law enforcement officials tracked down the location of the black radio station and confiscated the radio transmitter, resolving the problem.