Service workers' union Verdi on Sunday said it would call ground personnel out on strike just two days after their last walkout on Friday.
The stoppage was slated to begin at 4am Monday and last until 5am on Tuesday, affecting some 660 flights.
But the union said in a statement Monday that it now plans to extend the walkout until early Wednesday morning.
Some 195 flights were cancelled at Schönefeld, while 465 were affected at Tegel, airport operator FBB told AFP Monday.
"We ask all passengers to contact their airline and find out the status of their flight before setting off," said FBB spokesman Daniel Tolksdorf.
Verdi wants higher pay for around 2,000 ground staff in Berlin, including those registering passengers and loading baggage. Specifically they have called for a raise of €1 per hour for those on contracts of at least 12 months. Currently ground crew members earn on average €11 per hour.
An employers' group they have been negotiating with has offered an incremental increase in pay of 8 percent over the course of three years. But Verdi rejected this offer.
Employees walked out twice in February as the union ratcheted up pressure.