After a series of disruptive labour strikes in Germany’s aviation industry, key wage negotiations were to resume on Thursday involving the trade unions for tens of thousands of workers. German airline Lufthansa is to return to talks with the trade union for flight attendants, UFO, over their demands for 15% wage hikes and bonuses for about 19,000 flight attendants at Lufthansa and its subsidiary Lufthansa Cityline, union sources told dpa. On Friday, trade unions representing around 25,000 aviation security workers who screen passengers and baggage at numerous airports around Germany will begin…