Europe-US routes reveal surprisingly low load factors despite strong carriers

Between April 2025 and March 2026, nearly 40 passenger airlines combined to transport 78.4 million travelers nonstop between Europe and the United States, according to the US Department of Transportation (DOT). While the collective load factor averaged a robust 83.3%, this figure masks significant variation across individual routes. Several notable Europe-US airline corridors reported shockingly low seat occupancy rates despite the strong overall market.

Traffic growth over the period was minimal, with passenger numbers rising by only 0.5% year-over-year, representing an increase of roughly 351,000 travelers. Meanwhile, the number of seats offered rose at a rate double that of traffic growth, resulting in a dip in the average load factor. Contributing factors include elevated travel costs to the US and geopolitical tensions, which may have dampened demand on specific routes.

DOT data reveals the ten Europe-US routes with the lowest load factors during this period, all falling below 67%. These routes span a mix of major gateways and secondary airports, with some having already been discontinued. For example, Lufthansa's flight from Frankfurt (FRA) to Minneapolis registered a 56.6% load factor before Lufthansa ceased this service in April 2025 and replaced it with leisure carrier Discover.

Aer Lingus operated two underperforming routes: Dublin (DUB) to Minneapolis and Denver, each with load factors just over 61% and 64% respectively. The Minneapolis route resumed service in April 2024, paralleling Delta's May 2024 entrance onto the same corridor. The Dublin to Denver service began in May 2024 but has since raised questions about its viability given the consistently low occupancy levels.

Other carriers with notably low-performing transatlantic services include Icelandair, which operated from Keflavik (KEF) to Detroit (DTW) and Miami. The DTW route, launched in May 2023, ended in January 2026 after load factors hovered around 64%, despite direct competition from Delta Air Lines, which serves the market seasonally. Icelandair's newer Miami route, started in October 2025, was also among the lowest load factors tracked at 66.8%.

Finnair's Helsinki (HEL) to Seattle (SEA) service exemplifies how rapid expansion can lead to declined load factors. Although passenger numbers increased by 70.8% year-over-year to about 30,571 travelers, capacity more than doubled as the airline increased frequency and downsized to a smaller aircraft on this 7,697 km route. This mismatch caused the load factor to drop sharply from 84.7% to 66.8%.

United Airlines also reported low seat occupancy on its London Heathrow (LHR) to Los Angeles service, with a 66.9% load factor. This was despite United cutting frequencies by half, which aimed to rebalance capacity with reduced demand on that corridor. Singapore Airlines' Frankfurt to New York JFK route, only partially covered by the data possibly due to fifth freedom operations, similarly showed a load factor under 67%.

Several routes with low occupancy have since been discontinued, underscoring the difficulty in sustaining transatlantic services amid fluctuating demand and competitive dynamics. Airlines have responded differently, adjusting frequencies, terminating services, or switching aircraft types to improve performance. Aer Lingus and Icelandair, for example, face decisions regarding service continuation or scaling back given persistently weak load factors.

This data signals not only market overcapacity on certain Europe-US routes but also illustrates how strategic timing, competitive responses, and aircraft deployment profoundly impact route viability. The period’s slight passenger growth coupled with accelerating seat supply increased pressure on airlines to optimize offerings to maintain sustainable load factors and profitability.