Nok Air and NokScoot want to relocate their base operations to the derelict domestic terminal at Bangkok's Don Mueang airport.
The low-cost airline group intends to pursue the plan with Airports of Thailand Plc (AoT) to avoid overcrowding at the two existing passenger terminals.
"We're keen on migrating our operations to the old domestic terminal to raise efficiency and passenger service quality," Nok Air chief executive Piya Yodmani told the Bangkok Post.
The airline group believes the old domestic terminal, left unused for over a decade because of the ever-changing development plans for the airport, should be put to good use.
It is imperative to optimise existing facilities to relieve the critical congestion at Asia's oldest operating airport before long-term development begins, he said.
Some 37.2 million passengers were crammed through Don Mueang in the fiscal year to September this year, said the AoT, a 7.2% increase year-on-year. The airport's rated capacity is 30 million passengers a year.
The combined passenger volumes for Nok Air and its medium-to-long-haul affiliate NokScoot, is close to 10 million a year, and relocating that volume would considerably ease congestion at passenger terminals 1 and 2.
The airline would hold discussions with AoT on the proposal, the realisation of which would depend upon what the airport authority's intentions are for the old terminal.
The airline group has yet to carry out an in-depth assessment of the economic viability of running operations through the airports.
In addition, the cost of restoring the old domestic terminal has to be considered within the overall context, said Mr Piya.
It is unlikely that the airline group will put any money into the restoration, but will instead pay a leasing fee to AoT for the usage of the old domestic terminal, he noted.
Officials of airlines operating at Don Mueang noted there is a restriction on the numbers of aircraft which Pier 6, the closest to the old domestic terminal, can serve.