Aer Lingus will add three transatlantic routes in 2016.

Ireland’s national airline will begin year-round service five days a week between Los Angeles and Dublin in May, daily year-round service between Newark and Dublin in early September and daily year-round service between Hartford and Dublin in late September. The routes increase Aer Lingus’ long-haul seat capacity by 17 percent and represent that largest single expansion of its transatlantic network since it began flying across the ocean in 1958, according to the carrier.