Arrive at Dulles International Airport on your United Airlines flight and enter the terminal building. United Airlines operates out of A, B and C lettered gates, which are spread out among two separate structures.
Board the Aerotrain located in the A, B and C gate areas. Aerotrain use is only for domestic travelers. If you are arriving on an international United flight you must board the shuttle bus located in the D or A gate area or walk to to the luggage carousels located in the lower level of the main terminal building.
Collect your baggage and continue on to the U.S. Customs area. Once through customs locate the elevator or escalator and take it to the upper level of the main terminal building. Locate the United Airlines check-in lines at the western end of the terminal and begin the check-in process for your Aer Lingus flight. Aer Lingus and United Airlines share ticketing and check-in services at Dulles Airport.
Obtain your boarding pass and pass through the security checkpoint. Walk, take the shuttle or board the Aerotrain to your departure gate.
