Lufthansa pilots are on strike leading to cancellation of hundreds of flights. Due to strike Wednesday that grounded some 750 flights affected around 80,000 passengers. Most of the flight were domestic or within Europe.

The strike is active on short and medium haul operations. The Vereinigung Cockpit union said that on Thursday, it would extend its strike to long-distance flights. In past few months, the union has hit many Lufthansa units resulting into walkouts.

The argument is over the airline's plans to scarp transition payments for pilots to want to take early retirement. But the union wants no changes and payments to be maintained.

Flights by Lufthansa's subsidiaries Germanwings, Eurowings, Swiss and Austrian Airlines were not affected by the strike. Since last April, it is the 12th walkout over management plans involving the pilots' transitional pension scheme.

Currently the pilots can retire at the age of 55 and they can receive 60% of their pay until they reach the legal retirement age, which is 65 years. The airlines want to cut the arrangement. In 2014, the over and gain strikes led Lufthansa to cost around 232 million euros.

The company's personnel chief Bettina Volkens criticized the plan and termed it to be completely disproportionate.