Union Unite says a planned airport strike by 150 Birmingham workers will have a more serious impact on flight disruptions.
Security guards and terminal technicians are set to strike this week.
The warning comes after a High Court ruling banned the use of agency workers during stoppages.
Trade unions including Unite, challenged an earlier ruling through a judicial review.
It means employers are barred from recruiting agency workers to cover during strikes.
Unite general secretary Sharon Graham said: “This is a total vindication for unions and workers.”
“It was entirely counterproductive as it has hardened attitudes and unnecessarily extended strikes.”
“The only way this dispute will be resolved is with an acceptable offer from the company.”
The Birmingham Airport strike will be continuous.
