Given the investment that's been made in providing CBP at Shannon, as well as to the airport infrastructure itself, it makes no sense for US airlines to be using NOC for flights to the West coast. Maybe the intervention by Leo Varadakar was bad form, but it makes economic sense for transatlantic routes to be confined to Shannon. Just because Mayo has it's own airport doesn't mean it can support a transatlantic route in conjunction with SNN and other airports.