Fewer than 5 million passengers have passed through the country's 28 airports since the beginning of the year.
This represents a significant contraction compared to the same period last year, when 9.3 million passengers used the same airports.
Releasing the numbers for Jan 1-June 20, Department of Airports director-general Kawee Kasisam-ang attributed the substantial drop mainly to the Covid-19 pandemic, which prompted border closures and the suspension of scheduled domestic and international flights in early April.
The airports and airline industry bore the heaviest brunt from the ban in April before the Civil Aviation Authority of Thailand (CAAT) allowed some flights to resume in May. The ban on inbound commercial flights has not been lifted.
Mr Kawee said the 28 airports handled 4.2 million passengers from Jan 1-June 20, of whom 54 percent were on domestic flights.
A total of 18,700 flights operated into and out of the airports, a drop of 48 percent from the 35,800 flights in 2019, and almost all — 17,600 — operated on domestic routes.
With the lockdown being progressively eased in recent weeks, a limited number of domestic flights have have started slowly pushing up airport usage. A daily average of about 14,000 passengers have used the 28 airports since the latest, phase 4 easing of the Covid-19 restrictions was implemented on June 15.
The improved number, however, is a far cry from the daily average of 47,000 passengers who used the 28 airports in the same period last year.
The airports are currently managing a movement of between 70-80 scheduled flights a day, down from the daily average of between 160-170 flights in previous years.
The CAAT, meanwhile, said on Monday that the number of domestic passengers handled by airports nationwide, including the busiest two, Suvarnabhumi and Don Mueang, totalled 279,763 in the third week of last month, surging 23.9 percent from the previous week.
The number of flights, which also increased to 3,122 in the third week, up 18 percent from the week before, the recovery following the resumption of air routes and the reopening of Phuket airport, according to the CAAT.