The opening of Berlin's new airport has been delayed once again, and it remains unclear when the German capital's flagship hub will become operational.
Flughafen Berlin Brandenburg, the operating company, says that the planned opening date of 27 October is now unrealistic due to continuing problems with the terminal's fire warning and protection system.
Horst Amann, the airport operator's technical director, says it is too early to speculate about a new opening date.
On 18 December 2012, the company held a meeting between management, shareholders - comprising the Federal Republic of Germany and regional states of Berlin and Brandenburg - and fire protection equipment suppliers.
It then became clear that the opening had come under "increased risk", says Amann. He insists that he did not abandon the October target straight away, but rather undertook an assessment of whether it was still feasible.
This assessment was completed on 4 January.
Berlin's mayor, Klaus Wowereit, who heads the airport operator's supervisory board, is now fending off calls to relinquish his post at the helm of the city administration.
The Green party has called for an extraordinary meeting of the capital's local parliament for a vote of confidence against Wowereit. The meeting will likely place on 10 February, with a vote expected to follow at least two days later.
The mayor's office says in a statement that the airport's management will be reshuffled in a meeting on 16 January, and that its supervisory board will in future be led by the Brandenburg government.
Berlin Brandenburg airport was due to open on 3 June 2012, although the inauguration had already been delayed several times previously.
The June opening was called off in May primarily due to problems with the terminal's fire warning and protection system.
The airport operator subsequently targeted 17 March 2013 as its target launch date. But last September this was pushed further back to 27 October.