Ryanair is heading towards the biggest and most disruptive strike the company has ever faced on September 28 as it is facing labour walk-outs in Spain, Belgium, Holland, Portugal, Italy, and Germany, which could result in the cancellation of 8% of its flights.

Ryanair’s operations in Spain, alone, expect up to 1,800 cabin crew members to withhold their services in order to force the Irish low-cost carrier to to sign contracts with its employees based on national laws, rather than an all-inclusive Irish contract, according to the Irish news agency RTE.

Italy’s unions have, thus far, been successful in bringing Ryanair to the table. The airline announced that it agreed a Collective Labour Agreement in Italy cabin crew unions FIT CISL, ANPAC, and ANPAV. The deal does not, however, engage two of the unions that are planning strike action on Friday. Moreover, it is unclear how and when the agreement in principle will come into effect, and how.

Ryanair’s Chief Personnel Officer, Eddie Wilson, has invited unions from Germany, Portugal, and Spain to negotiate deals similar to the one struck in Italy.

In the Netherlands, local Dutch pilots are seeking additional sick-leave pay and other associated rights, saying Ryanair currently treats them as contractors rather than employees. Ryanair says it has agreed to move to local contracts as quickly as next year.

Last week, the European Commission warned Ryanair that it must abide by workers’ demands by granting them national contracts. To date, Ryanair employees sign an Irish contract and are compelled to receive their pay in Irish bank accounts, which affects their credit rating and incurs additional costs.

“The place where the worker gets up and goes back to sleep is what determines where the law is applied,” Employment Commissioner Marianne Thyssen said in a statement.

In 2017, the European Court of Justice ruled that workers must be able to seek protection in their country of operation and gave the national courts the legal basis to resolve labour disputes between Ryanair and its employees even if they have Irish contracts.