Checking in for your flight and receiving your boarding card are simple with the Aer Lingus App Check in. Transatlantic flights can be checked in up to 24 hours before departure, while European flights can be checked in up to 48 hours before departure. Your boarding pass will be available in the app once you’ve checked in. At the airport, you can either print it or show it on your phone. The Aer Lingus app can help you save time and money at the airport.