Just a day after the airline was forced to cancel around 600 flights following stoppages by ground staff, baggage handlers and maintenance workers at Germany's main airports, Cockpit called for three full days of strikes on Wednesday, Thursday and Friday.
"There has been no convergence between the standpoints of Lufthansa and Cockpit, so there will be industrial action from midnight on April 2 until 11:59 pm (2159 GMT) on April 4," the union said in a statement.
In a strike ballot last week, pilots from Lufthansa, Lufthansa Cargo and Germanwings had voted 99.1 percent in favour of possible strike action in pursuit of their demands for higher pay and better provisions for pilots nearing retirement age.
"We regret the disruptions for Lufthansa customers. Management still has the means to prevent this," Cockpit wrote and promised no further action until after the Easter holidays.
Lufthansa, for its part, called on the union to return to the negotiating table.
"We have four and a half days to avert any damage this might have on our customers," said personnel chief Bettina Volkens.
"We are prepared to resume negotiations at any time. With the goodwill of all concerned, we should be able to succeed in avoiding a strike," she said.
Yesterday, hundreds of flights were grounded all across the country as a result of strikes by the giant services sector union Verdi.
Verdi is seeking pay increases of 100 euros (USD 137) a month for 2.1 million employees in regional and municipal public service sectors, plus an additional pay hike of 3.5 percent.