If you have not reserved your seat when booking in Economy Class with Brussels Airlines, you will automatically be assigned seat when you check in online (from 24 hours before departure). With effect from 24 February 2020, any subsequent change of seat will only be possible on payment of a fee.* This fee will be between EUR 12 and EUR 75, depending on the route, fare and category of seat and will therefore be in line with the fees for advance seat reservation.
If you check in at the airport, you will still be able to change your seat free of charge.
* Exception: HON Circle Members, Senators and unaccompanied children (UMNR) may still change their allocated seat free of charge. This is also the case for all passengers booked in booking classes Y, M and B.