A record number of passengers using Lisbon's airport is proving a bittersweet achievement as daily delays and a lack of space to park planes threatens to strangle the goose laying golden eggs for Portugal's economy.
Tourists flocking to Lisbon to soak up some sun and while away evenings listening to Fado music in the city's bars has been one of the bright spots in Portugal's economy, which was wracked by the eurozone debt crisis at the start of the decade.
But with Lisbon's Humberto Delgado airport having already in 2016 passed its capacity forecasts for 2025, there are mounting concerns that without rapid investments it might soon act as a choke valve on the motor of Portugal's economy.
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In 2017, the airport set a new record of 26.7 million passengers, a 66% increase over four years. And traffic is up another 11% over the first eight months of this year.
The Portuguese government, national airline TAP and the tourism sector all agree: construction of a second airport for the capital needs to get underway.
The plan under discussion is to convert Montijo airbase on the opposite side of the Tagus river from Lisbon into a civil airport.
As a stop-gap measure, a little-used secondary runway at the current airport, located in the city's northern suburbs, will be closed to make space to park planes.
The Montijo project, which would take overall capacity to 50 million passengers per year, has been the subject of discussions since February last year between the government and ANA, the operator of 10 Portuguese airports that is owned by French construction and management firm Vinci.
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The discussions are well advanced and should be wrapped up soon, say both sides.
But for airlines, the wait is uncomfortable.
"The delivery calendar for our new planes is set, but I don't know yet if I'll have space to park them. It's really frustrating," the chief executive of TAP, Antonoaldo Neves, said at a recent conference.
"If we don't move forward with the necessary speed, all of Portugal will be left behind," he said.
TAP is the principal airline at Lisbon airport, and constraints there could begin to stunt their company's growth next year.
"What are we waiting for to move forward with the Montijo option?" questioned the head of the association of tourism firms, Francisco Calheiros.
Some estimates say Portugal stands to lose one million tourists per year because of the situation.
Prime Minister Antonio Costa recognised there is "no other solution" but said the government is waiting for the results of an environmental impact study to "make the decision absolutely irreversible".
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'Correct the mistake'
The situation Lisbon finds itself in is also part of the legacy of the eurozone debt crisis, which pushed the country into seeking an international bailout in 2010.
As part of the bailout the government slashed spending and investment, including abandoning plans to build an entirely new airport in a town adjacent to Montijo.
"We need to correct the mistake made when it was decided not to build an airport that we already needed then," said Costa.
For Thierry Ligonniere, the chief operating officer of ANA and a member of the management board of Vinci Airports, the problem is to some degree a consequence of success.
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"If we have difficulties at Lisbon airport, it is because traffic grew rapidly," he told AFP on the sidelines of the conference.
The conversion of Montijo would require ANA to make investments totalling several hundreds of millions of euros, the company estimates.
"We are content to be in a situation of investing so much money so quickly because that is saying good work has been done in traffic development," he said.
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