Signatories of the agreement include Thai Airways International, Thai AirAsia, Cathay Pacific, China Airlines, Emirates and Singapore Airlines.

The scheme offers discounts of up to 30% to airlines that increase passenger volume through Bangkok's gateway airport.

The rebates are based on a complex formula that compares a carrier's passenger volume this year with 2009.

Transit passengers and crew members are excluded from the scheme.

The new metric replaces across-the-board cuts in landing fees implemented by the state-controlled airport operator over the past year as part of a relief package to help the aviation industry weather the economic downturn.  AOT expects to see the other 70 international carriers operating through Suvarnabhumi sign up for the incentives over the next two months.

Suvarnabhumi general manager Nirandra Theeranartsin said that the scheme would encourage airlines to channel more passengers through the airport, by increasing flight frequencies, deploying larger capacity aircraft and opening new routes through the airport. These dynamics would directly benefit Thailand's tourism industry.

"It's a win-win situation, I think all airlines will join the scheme," he said.

AOT hopes the programme will help it achieve its target of 42 million passengers passing through the airport this year. Suvarnabhumi handled 40.5 million passengers last year.

But airline managers said they would prefer AOT to continue with landing-fee discounts, even at a reduced rate of 20%.

Offering rebates for landing fees was intended to be a long-term part of AOT's new business model to boost traffic through Suvarnabhumi.

AOT is working on a new incentive scheme for its regional airports, similar to the one at Suvarnabhumi, to increase passenger traffic in October when the current flat reduction in landing fees expires.