Following Monday’s four-hour strike at Berlin’s Tegel and Schönefeld airports which saw 80 flights delayed, union-backed strikes on Thursday, January 10, at Cologne, Dusseldorf and Stuttgart have seen nearly 640 flights canceled.

Verdi, Germany’s largest trade union, is seeking an across-the-board wage increase to €20.00/hr (US$22.79) for all security staff checking passengers, freight, goods and other airport employees at all hubs, and is in negotiation with BDSL, the organisation representing Germany’s airport security companies.

The strike at Stuttgart airport began at 3:00 a.m. local time (2:00 UTC) on Thursday while the strikes at the Cologne/Bonn and Dusseldorf airports began at midnight.

Over half of the 1,050 flights from Dusseldorf, Cologne/Bonn and Stuttgart have been canceled.

The airport association ADV had expected at least 110,000 travelers to be affected. Stuttgart Airport urged would-be passengers to arrive early in anticipation of “long waiting times.”

BDLS has rejected Verdi’s demand on the basis it is too high and as wages vary by airport and by precise role, a €20.00 flat hourly rate would represent unusually high increases for certain employees. Negotiations are expected to resume on January 23.

Verdi has warned that a breakdown in negotiations could lead to further strikes at German airports.