The opening of Berlin’s troubled new airport is to be postponed to spring 2018, marking the project’s latest delay, according to Germany’s Die Zeit.

The Berlin Brandenburg Willy Brandt Airport was originally set to open in 2011 but cost overruns and construction errors caused repeated delays. Latest estimates have been for a late 2017 opening, but an airport spokesperson said an announcement would be made in January on the exact date.

Germany’s biggest carrier Lufthansa had described a winter 2017 start-up date for the terminal as “unsuitable,” instead suggesting that 2018 is more realistic. The project plan is for a €5.4 billion new terminal in the southeast of the city to operate alongside the city’s Schönefeld Airport.

The Tegel airport in the northwest of the German capital would close.