Our tour ends in Belfast on a Saturday. We would like to take the bus to Dublin International Airport that same day so as to fly home that same day. Do the busses usually run on schedule or do we risk a delay and a missed flight? We are looking at a flight departure at 3:00 p.m.
If you Google for the route you will find posted schedules. But you are going to need an awfully early tour exit. You will have to get to the bus depot, the ride itself is a comfortable 2 hour (IIRC) ride to Dublin airport, but due to the delays exiting - as you first have Dublin's security followed by the lengthy cue to go through S security (actually easy) and then US passport control - you really do need to give this airport 3 hours (and that is assuming you have your boarding passes in advance). And that means being able to board a bus that leaves by 10AM .
Most everybody on this forum would suggest you not do this, and urge you to be within easy reach of the airport where your expensive cross-atlantic flight leaves from.
Looking at the Dublin Express bus tracker feature for today ( Oct 29) of the 5 departures shown, 3 minutes behind schedule was the latest a bus departed. All look to have arrived on the 1 hr 50m scheduled travel time.
Obviously a small sample size, but a consistent result.
I would be inclined to take the 8:25 departure ( 10:30ish arrival) to have some buffer for a delay, rather than the 9:25 departure which has a very slim margin for an 'oops'.
When we were there four years ago, we were visiting with Northern Ireland residents in line waiting for the Belfast bus from the Dublin airport. They traveled internationally for sports and used the bus to get to/from the airport whenever they traveled. We always have trip insurance, just in case, but I wouldn't think the delay risk would be high.
This is from the tour info: "Most tour members arrange to fly in and out of Dublin (DUB). If you prefer to fly out of Belfast (BFS), select "multicity" on flight-booking websites. The coach from Belfast direct to Dublin Airport takes about two hours and departs hourly 24 hours a day. Your guide can help you book it when you arrive."
I just took a RS tour that ended in Belfast on a Thursday. Everyone returning to the US took a bus to Dublin Airport for flights departing to the US that same day. No one headed to Dublin the evening before departure. I took a scheduled 8:25 a.m. Dublin Express bus that left about 10 minutes late and arrived at the airport by 10:30, with my flight departing at 2 pm. I had about 1.5 hours of waiting time after clearing initial security. The extra US security lines moved very fast. People who took earlier buses reported similar extra time.
There's three operators who run that route
www.translink.co.uk
Translink are the public transport operator in Northern Ireland and they run all buses and trains in Northern Ireland including cross border routes into Ireland
www.dublinexpress.ie
These are a private company who operate the routes between Belfast and Dublin airport and Dublin city
And www.aircoach.ie
Another private company and operating between Belfast and Dublin.