The radar problem affecting Suvarnabhumi Airport's airtraffic control services on Thursday evening was caused by a malfunction of the airport's Uninterruptible Power Supply (UPS) system, Aeronautical Radio of Thailand (Aerothai) said yesterday.
Aerothai president Squadron Leader Prajak Sajjasophon told the press conference that the UPS system malfunctioned because of a short circuit in a capacitor. As a result, the electricity supply for the airtraffic control services went dead for 30 minutes while a backup radar that uses the same UPS system was also down.
The company implemented an emergency plan using nonradar and radio communications to control air traffic instead. However, this reduced the company’s flighthandling capacity, resulting in delays to some 50 flights, he explained.
Thirteen flights were diverted to other airports (six to Utapao, two to Chiang Mai, two to Phuket, two to Kuala Lumpur and one to Siem Reap). Twenty flights had to wait at the airport, with the longest waiting time being 105 minutes for a TG140 SuvarnabhumiChiang Rai flight, while another 15 already in flight were put into holding patterns, the longest being Qatar Airways flight 617 from Ho Chi Minh, which was held for 71 minutes. Aerothai managed to find the cause of the problem and fix it within 30 minutes, Prajak said.
Deputy Transport Minister Chatchart Sitthipan said the problematic devices were replaced by new ones. In order to prevent a recurrence, Aerothai would separate the UPS and radar systems in use on the fourth floor of Aerothai’s building from the backup set on the sixth floor, which would be done by August, he said.
Transport Minister Jarupong Ruangsuwan said the incident showed that the airport’s airtraffic control safety level was still high, and caused only inconvenience for passengers. The minister apologised to the public and the affected passengers for the “unavoidable” inconvenience, adding that a factfinding committee was set to determine if the problem stemmed from faulty equipment or human error within 15 days. The related agencies would produce a handbook with guidelines for use in emergency drills.