Belfast remains one of the more curious gaps in transatlantic aviation: there's no nonstop option, so business class from Los Angeles to Belfast always routes through a connecting hub, typically Chicago, Newark, JFK, Philadelphia, or Dublin, depending on which of the three American carriers you choose. I've stitched together this itinerary more times than I can count, and the truth is the connection is a feature, not a bug — it lets you break up a nearly 17-hour total journey with a proper lounge reset. American Airlines routes efficiently through its Flagship hubs with 777-300ER or 787-9 Flagship Business seats (all direct-aisle-access, fully lie-flat), Delta leans on its Delta One Suites aircraft out of JFK or Atlanta with sliding doors on most widebodies, and United connects well through Newark or Chicago using Polaris seats on 767s and 777s, which remain among the more private herringbone layouts in the U.S. fleet.
My preference on this routing is Delta via JFK when schedules align, since the JFK Delta One Lounge is worth arriving early for — it's one of the few U.S. lounges that genuinely rivals European business lounges, with restaurant-quality dining that makes the eventual short transatlantic-to-Ireland hop feel like an afterthought. An insider tip few frequent flyers exploit: booking the JFK-to-Dublin-then-BFS combination (rather than direct into Belfast City or Belfast International via London) sometimes yields far better award and upgrade availability, since Aer Lingus's joint venture with American opens up seats not visible when searching Belfast-only itineraries.
Deal-wise, this is a shoulder-season route through and through — January, February, March, October, and November consistently produce the softest business class fares, largely because Belfast's tourism peaks are summer and around its concentrated event calendar, leaving carriers eager to fill premium cabins in the off-months. Given how erratic pricing swings can be on a connecting itinerary like this, setting up fare alerts is genuinely the smartest way to catch a premium seat before it disappears.
