Trondheim rarely appears on the American business traveler's radar, which is precisely why the routing deserves closer scrutiny before you dismiss it as too obscure to bother with. There is no nonstop option: business class from Jacksonville to Trondheim always routes through a European or Scandinavian hub, with the journey typically spanning around 9.5 hours of total flight time once you factor in the connection. My preferred build is SAS via Copenhagen or Stockholm, since SAS actually operates the Trondheim leg with regularity and their A321LR business class on transatlantic-adjacent European routings has improved noticeably with the newer cabin retrofits. Lufthansa via Frankfurt and KLM via Amsterdam are the other realistic paths, both offering long-haul business product from JAX-adjacent gateways (you'll typically connect domestically first) before switching to a European narrowbody business cabin for the final hop north.
Having flown all three combinations repeatedly, I lean toward the KLM routing through Amsterdam when schedules align, mainly because Schiphol's connection times to Trondheim are generous enough to shower in the KLM Crown Lounge without sprinting — a small luxury that matters after a transatlantic sector. Lufthansa's Frankfurt hub works well too, particularly if you can snag one of their long-haul aircraft still running the Business Class product rather than older configurations on secondary transatlantic feeder flights. The insider tip most people miss: book the Trondheim segment as a separate short-haul business fare only if the through-fare from JAX isn't competitive — Scandinavian carriers often price the Nordic domestic-style hop cheaper standalone, and mixing it with a discounted long-haul business fare from the Southeast can undercut a single carrier's total itinerary price.
Late spring through early autumn — May through September — is when Trondheim actually makes sense, with long daylight hours and milder weather rewarding the extra connection time. Given how thin premium cabin allotments are on this corridor, setting up fare alerts for JAX–TRD business class itineraries is genuinely the smartest way to catch the occasional pricing anomaly before it disappears.
