Brussels Airport expects around 140 flights to be cancelled on Friday as ground handler Alyzia’s staff join a national day of union action in Belgium.

Alyzia, one of two passenger ground handlers at the airport, will operate with limited staff. About half of the flights it normally handles can operate as planned, the airport said. Alyzia serves around 20 airlines, handling baggage, ramp operations and aircraft cleaning.

Brussels Airlines, the airport’s largest carrier, expects to cancel about 40 percent of its Friday flights. It had expected around 30,000 passengers that day. Affected customers can choose another itinerary or a refund.

Flights handled by the other handler, Aviapartner, are not expected to be affected. That includes flights operated by Ryanair and TUI fly. British Airways services are also running as normal.

Demonstrations in Brussels may also disrupt buses, trams and the metro. Passengers have been advised to check their flight status before travelling.