The union representing Germany’s air traffic controllers called Tuesday for them to stage a six-hour walkout later this week . It called for a walkout between 6 a.m. and noon (0400-1000 GMT) on Thursday, declaring that the latest offer from employers was unacceptable and negotiations are at a point where there is “no alternative to a strike.” It has been seeking a one-year wage deal with a 6.5 percent pay increase. The call for a strike on Thursday came a day after the union released results of a ballot of members conducted over recent weeks that showed an overwhelming majority backing a walkout. Germany’s air traffic control authority has some 6,000 employees. The authority’s personnel director, Jens Bergmann, said it would seek a court injunction preventing Thursday’s walkout, German news agency DPA reported. The authority also could ward off strikes, at least for now, by taking the dispute to arbitration.