Five domestic flights were delayed when heavy fog again blanketed Chiang Mai international airport this morning.
Airport authorities reported poor visibility at the airport or just 500 metres at 7.30 am.
The low visibility forced the airport to switch on runway lights while advising all operations at the airport to be on alert.
But 10 minutes later the visual distance dropped to 100 metres, forcing the airport to halt all flight operations in the airport area for safety reason.
The situation was back to normal at 7.50 am after usual distance becoming clearer with all fog vanished.
Five flights scheduled to take off and land at the airport between 07.30-08.00am were delayed.
They included Thai Smile's Flight WE150, Thai AirAsia's FD101, FD3437, and Nok Air's DD 8302.
All the four flights have to circle for about 10 minutes before getting permission for landing.
Nok Air's Flight DD8301 which was scheduled to takeoff from Chiang Mai to Don Mueang was put off from 07.45 am to 8.09 am.
The airport said such low visibility could happen again during this cold season and advised passengers to prepare enough time for their flights.
Source: Thai Public Broadcasting Service (Thai PBS)