Hamburg airport, Germany's fifth busiest, expects little negative impact from a strike on Friday by technical staff, its chief executive said.

"We are working to make contingency plans in such a way that passengers do not notice anything," Hamburg Airport CEO Michael Eggenschwiler told a news conference on Thursday.

He said the 200 employees at the airport's Real Estate Maintenance GmbH (RMH) subsidiary, responsible for the technical maintenance of infrastructure, are support staff and not directly involved in the processing of flights.

"So, it could happen that an escalator breaks down and no one comes to repair it," Eggenschwiler said.

The trade union Verdi, which called for the strike on Wednesday, said it was demanding an 8.5% salary increase over 12 months for staff at RMH while the company had offered an increase of 4% per year for two years.

The walkout comes as school holidays in the region begin and amid an industry-wide shortage of personnel.

Trade unions have called for attention to the needs of overworked employees as airlines, which slashed jobs during the COVID-19 pandemic, struggle with surging air travel demand. (Reporting by Klaus Lauer; writing by Zuzanna Szymanska; editing by Miranda Murray and Jason Neely)