German trade union Verdi has called for ground staff at Berlin airports Tegel and Schönefeld to strike today. The 24-hour strike, which is scheduled to begin at 4:00 am local time, is expected to have a considerable impact on air traffic to and from Berlin.

Airberlin said in a statement that flights may be canceled or delayed on short notice. Exceptions to the cancellations are likely to be long-haul flights.

The strike coincides with the world’s largest travel trade fair, ITB Berlin, and today is a peak travel day when visitors from around the world are scheduled to travel home.