Belgian Ryanair pilots will go on strike for the fourth time in two months over Sept. 14-15, seeking higher pay and better working conditions, their union told Belgian broadcaster VRT on Thursday.

Pilots residing in Belgium have been pushing the Irish budget airline for months to reconsider a proposed reduction in the number of rest days for pilots, which they claim are unlawful.

The pilots are also seeking higher pay to compensate for inflation.

The strike will affect Ryanair flights to and from Charleroi airport, but it is unclear yet how many pilots will join the strike and how many flights will need to be cancelled. (Reporting by Bart Meijer Editing by David Goodman )