Airport Express 300

The airport 300 bus is probably the most convenient way to get too and from Belfast International Airport from Belfast City Centre.
It is operated by Translink and not Belfast International Airport and to be honest they operate it to perfection. I have got this bus plenty loads of times when there is no one available to pick me up from Aldergrove. It departs every 15 minutes (at peak times), 24 hours a day which is pretty impressive. One thing that is worth noting is that it departs and arrives in to Europa bus centre (Underneath The Europa Hotel) and in the wee small hours of the morning there won’t be any onward travel on offer apart from the City Taxis.
The Bus itself costs £7.50 for a single and £10.50 for a return which is reasonable when you consider that a taxi one way will be around £30. I have never had any problems with this service. The buses are usually well maintained and the journey is always smooth.