Verdi had also called for strike of security staff at the airports Frankfurt, Bremen, Hamburg, Hanover, Stuttgart, Düsseldorf and Cologne/Bonn. In the ongoing wage negotiations with the Federal Association of Aviation Security Companies, Verdi is demanding, among other things, that the hourly wage for aviation security services be increased by at least one euro per hour and that wages be aligned regionally. Four rounds of negotiations failed to produce a result. The employers had accused the union of excessive demands.