The Airports Department has proposed building a new airport in Nakhon Pathom province west of Bangkok to relieve congestion at the capital's two main gateways.
The 20-billion-baht facility, to be built on 3,500 rai straddling Bang Len and Nakhon Chaisi districts, will take four years to put up, said Jarun Meesomboon, the department's deputy director-general.
The proposal will be forwarded to the Transport Ministry, which will consider the matter before it goers to cabinet.
"The investment could be in the form of a public-private joint venture or a state-owned project, pending further study," he said.
Various private groups had shown keen interest in the project, he said, drawn by a high economic internal rate of return, or EIRR, of more than 20%.
"We project more than 1 million passengers a year initially, potentially on par with key regional airports such as Khon Kaen and Surat Thani airports," he said.
A hearing will be held next month to gather more information before officials draft the terms of reference.
If approved, construction could begin in 2023.
Suvarnabhumi Airport was first proposed in 1973 but the plan was shelved amid the political turmoil of the 1970s.
Work did not begin in earnest until 1996 when New Bangkok International Airport company was formed, and the airport opened in 2006.
Suvarnabhumi is now bursting at the seams, handling 70 million passengers a year at a facility designed for 40 million.
A revised plan to build a 42-billion-baht second terminal was recently shelved amid controversy as authorities said it deviated too much from the original master plan.
Discussions are under way on a new approach.
If the Nakhon Pathom airport goes ahead and all phases are completed, it will be able to handle up to 25 million passengers a year.
Mr Jarun said the new airport had good potential thanks to its location less than 50 kilometres from downtown Bangkok and access to the Bang Yai-Kanchanaburi motorway.
In addition to domestic flights, the new airport can support Asean services.
"Don Mueang and Suvarnabhumi are struggling to find slots and serve private jets," he said.
"The new airport will accommodate commercial airlines, private jets, chartered flights, helicopters and survey services."
As for land expropriation, a study shows the site has the least dense population -- 200 households on 400 plots -- so acquiring the land shouldn't be hard, he said.