A group of MPs will visit Cardiff Airport later as they examine whether air passenger duty (APD) should be set in Wales.
The amount of tax paid on flights (APD) for Welsh customers is currently set by the UK Government, while Scotland and Northern Ireland are able to cut the cost of longer haul flights by reducing APD.
The Welsh Government has long called for the devolution of APD. However, the UK Government has resisted calls, saying any reduction in APD in Wales would negatively impact on Bristol Airport.
The Welsh Affairs Committee will also consider the steps the airport has taken to get ready for Brexit.