Brisbane Airport could start turning flights away if a deadlock over paying for a new runway can't be resolved.
More than 20 million people fly through the airport every year, and experts say the move could strangle Brisbane.
The skies are more crowded than ever around Brisbane airport - each day, there are one hundred more takes offs or landings, than there were a year ago.
"We are, during the weekdays, the second busiest single runway airport in the world," Rachel Crowley from the Brisbane Airport Corporation said.
"In the peak times from now, we really can't accept any more flights."
The solution lies in the trees to the west of the airport - a parallel runway due to be finished by 2020, costing $1.3 billion.But Brisbane Airport wants airlines to pay a quarter of that cost through a ticket surcharge starting soon, long before they'll get to use the runway.
"This should be all about them building the infrastructure and then certainly the customers paying for it after it's completed," Aviation analyst Geoff Thomas said.
For months Qantas has led a loud campaign against the ticket surcharge.
"I don't see why airlines today should be funding airport infrastructure for the future, and prepaying for infrastructure that's giving us no benefit today," Qantas CEO Alan Joyce says.
Brisbane airport says if the airlines don't pay, the runway won't be built.
Ticket surcharges aren't new but there's never been one slugged so far in advance.Swampy soil will have sand pumped into it from Moreton Bay to become the foundations of the new runway. But it will have to settle for up to three years before construction can start.
If the standoff can't be resolved Brisbane Airport will put up the no vacancy sign.
"So it is a longer build than you'd find probably at a lot of other airports, so that does make the project a bigger challenge," Ms Crowley said.
"There does come a time when the number of slots, so to speak, are full. And after that, no-one else can come in."
The state government says it won't intervene in what it calls a commercial dispute.