Khon Kaen airport resumed operation using temporary passenger service booths Friday afternoon as investigators looked into the cause of the morning's fire.
Airport director-general Darun Saengchai ordered booths set up in the parking lot to serve departing passengers.
Services for arriving passengers were operating out of the Rachawadee Hotel, in front of the airport.
Traffic control remained functional and luggage X-ray machines were receiving power from an outside source, Mr Darun said.
Boarding passes were being handwritten instead of issued from computers. After check-in, departing passengers were being taken by buses to their planes.
Buses also carried arriving passengers and their luggage to the hotel.
Khon Kaen airport was again serving commercial, private, training and government flights, he said. Services resumed there at 12.40pm.
"Such operations will continue throughout the day. Flights may be delayed. However, operations have resumed. We are not using Udon Thani airport because it is already packed with flights and passengers," Mr Darun said.
Normally Khon Kaen handles 36 flights a day. No passengers were stranded in the afternoon, he said.
The airport director-general said police would be still looking into the cause of the fire. He confirmed it started in the airport's electricity control room on the third floor of the passenger terminal.
Damage was contained in the power control room. The terminal was being cleaned and should be back in normal service on Saturday, Mr Darun said.
Arriving passengers are guided to buses at Khon Kaen airport after it reopened to flights early Friday afternoon. (Photo by Chakkrapan Natanri)