The trade union verdi has again called ground staff at German airline Lufthansa out on strike on Thursday and Friday, a move that is expected to affect passengers. The industrial action over pay and conditions is to begin in the passenger-related areas at 4 am (0300 GMT) on Thursday and end at 7:10 am on Saturday. There have already been two waves of strikes in the current wage dispute for around 25,000 ground staff, each of which paralysed passenger traffic for around a day. Last week, Verdi staged strikes in Lufthansa’s technical and cargo handling departments in order to force the company t…