The power disruption at Hong Kong International Airport (HKIA) Thursday night was caused by power distribution system incident, and the power supply system and backup power system were intact, said Wong Yiu-fai, Airport Authority Hong Kong's head of technical services and procurement.

Wong said at a press conference that the power disruption was due to five switchgears of the automatic power distribution system being tripped, which was a very rare case and has never happened at the HKIA.

"We are contacting the manufacturer of the system and we are investigating the cause and will explore measures to improve the system and prevent a recurrence of such an incident", said Wong.

According to the Airport Authority, the Operation of the Air Control Tower was not affected following reports of partial power failure at the Passenger Terminal Building shortly after 7:00 p.m. Thursday. Only two flights delayed for a while because of the power failure.

The power supply resumed at 7:45 p.m. Thursday while the operation of the whole Passenger Terminal Building became normal at 8:42 p.m. Thursday.