The fire was caused due to malfunctioning of batteries, Airport Director H S Suresh said in Chennai.
The battery bank area of the ATC tower was engulfed in fire following an explosion in the UPS (uninterruptible power supply) system of the battery bank in the technical equipment room that supplies power to advance surface movement guidance and control system at around 2.20 AM. But there were no casualties.
"An enquiry has been ordered by Ministry of Civil Aviation. DGCA has been directed to conduct the enquiry to identify the cause of the incident and suggest remedial measures and submit a report at the earliest," an official statement issued in New Delhi said.
Five international flights arriving at the Chennai airport, between 2.30 AM and 5 AM, had to be diverted to Bangalore and Hyderabad.
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Four flights were diverted to Bangalore and one to Hyderabad as part of the contingency plan and standard operating procedures (SOPs) after the officials were forced to vacate at the area control centre due to thick smoke.
During this period, six departures were also delayed which had a cascading effect on 13 more departing flights.
The flames were noticed by the maintenance personnel on duty in the technical equipment room on the third floor of the Air Traffic Services (ATS) complex.
As a preventive measure, power supply and airconditioning was switched off as technical and area control centres were engulfed in thick smoke.
It was restored at around 3 AM, after the smoke got cleared. There were no damage to the equipment and the system, the statement said.