Berlin - Pilots at Lufthansa ratcheted up a 35-hour strike on Tuesday, grounding many intercontinental flights by the German flag carrier.
Expanding the strike which began midday Monday with walkouts on domestic and European routes, unionised pilots refused to fly to and from Asia and the Americas and other far destinations for the strike's remaining 18-hour period on Tuesday.
Lufthansa said almost all its long-haul flights out of its main hub, Frankfurt, were cancelled, but about half the flights from its number-two hub, Munich, were operating as scheduled with non-unionised pilots at the controls.
The strike is the eighth this year by the Cockpit Union, which is fighting to preserve an early-retirement scheme that allow pilots to leave after 55 on generous benefits.
Lufthansa wants to raise the threshold to 60.
Altogether, Lufthansa has cancelled 1,511 flights and estimates the travel plans of 166,000 passengers have been disrupted.
As in past strikes, it has rescheduled their travel, offered refunds or found hotels for the stranded.
A Frankfurt international airport spokeswoman said the situation at Lufthansa counters there was calm, with ground staff providing food and drink to passengers waiting out the strike.
The Cockpit Union said the pilots would return to duty after midnight Tuesday (00:00 SA time).
The previous day, Chancellor Angela Merkel criticised the strikers, whose stoppage comes on the heels of a labour walkout on much of the German rail system.
“She hopes these conflicts will be settled quickly,” said Merkel spokesman Georg Streiter.
The early retirement scheme is a special benefit for the 5,400 pilots employed at Lufthansa, its budget offshoot Germanwings and Lufthansa Cargo and is not available to cabin crew or ground staff.
Europe's largest airline is battling to reduce costs in the face of stiff competition from budget airlines and emerging Middle East carriers. - Sapa-dpa