American Airlines has built one of the largest transatlantic networks among US carriers, connecting its major hubs with cities across Europe. Yet historical traffic data for the 12 months through June 2026 shows a striking gap between the airline’s busiest and emptiest international corridors. While American averaged an 85.01% load factor across its transatlantic network, 11 routes recorded average occupancy below 80%.
That difference matters because load factor measures the proportion of available seats occupied by passengers. A route operating at 73% is carrying significantly fewer travelers relative to its capacity than one operating above 90%, even though the underlying reasons can vary considerably. Seasonal demand, aircraft size, competition, connecting traffic and schedule patterns can all influence the result.
According to historical data made available by Cirium, the weakest-performing route in American’s transatlantic network was Raleigh-Durham (RDU) to London Heathrow (LHR). It recorded an average load factor of just 73.3%, making it the only route in the group to fall close to the low-70% range. The result is particularly notable because London is one of the largest and most established international markets in American’s network.
The four emptiest routes all involved the United Kingdom, although three different US gateways were represented. American’s New York JFK–London Heathrow service averaged 75.98%, while Boston Logan–London Heathrow reached 76.29%. Between them was New York JFK–Edinburgh, which recorded 74.78%, making it the second-emptiest route overall.
American Airlines’ Weakest Transatlantic Routes
The pattern becomes more interesting when the remaining routes are considered. Charlotte Douglas–Munich averaged 77.13%, while Los Angeles–London Heathrow recorded 77.57%. The latter is a particularly long transatlantic corridor, linking American’s West Coast operation with one of Europe’s most important aviation markets.
American’s Philadelphia–Zurich route posted a 78.46% load factor, followed closely by Charlotte–Frankfurt at 78.73%. Philadelphia is an important American hub with extensive European connectivity, while Frankfurt and Zurich are both major business and connecting markets in continental Europe.
The final three places in the sub-80% group were Philadelphia–Amsterdam at 79.38%, Dallas/Fort Worth–Zurich at 79.82%, and Las Vegas–London Heathrow at 79.96%. The Las Vegas figure needs particular context because only a limited number of flights operated around CES 2026, meaning its result does not necessarily represent the same year-round demand pattern as a daily transatlantic service.
Together, these figures reveal that the weaker routes were not concentrated in a single type of market. They included major US hubs such as Dallas/Fort Worth, Philadelphia and Charlotte, large international gateways such as Los Angeles and New York, and leisure-oriented Las Vegas. The common factor was simply that average seat occupancy remained below American’s overall transatlantic benchmark.
JFK-Edinburgh Shows the Role of the A321XLR
One of the more closely watched services in the group is JFK–Edinburgh. American has positioned the route as an example of what the Airbus A321XLR can accomplish, allowing a narrowbody aircraft to connect New York with Scotland on a long-haul route.
Brian Znotins, American’s Senior Vice President of Network and Schedule Planning, previously described the A321XLR as a “game-changing” aircraft when discussing the Edinburgh service. The aircraft’s combination of long range and smaller capacity gives American another way to serve markets that might not justify a larger widebody aircraft throughout the year.
The 74.78% average load factor therefore provides an interesting snapshot of the route’s performance during the measured period. It does not, by itself, explain profitability or indicate whether American considers the service successful. Load factor is only one component of an airline route’s economics, and smaller aircraft can potentially change the financial equation even when occupancy is below the network average.
The Strongest Routes Were Above 92% Full
The contrast with American’s best-performing transatlantic routes is substantial. Four services recorded average load factors above 92% during the same 12-month period, with Chicago O’Hare–Athens leading the network at an impressive 93.62%.
Dallas/Fort Worth also produced two of the strongest results. Its routes to Madrid and Rome recorded load factors of 92.31% and 92.29%, respectively. American’s Miami–Madrid service completed the top four at 92.06%.
The difference between the strongest and weakest routes is therefore considerable. Chicago–Athens averaged more than 20 percentage points higher occupancy than Raleigh-Durham–London. That spread illustrates how dramatically demand can vary across an airline’s transatlantic network, even when every route operates under the same overall corporate strategy.
For American Airlines, the figures provide a useful picture of where available transatlantic capacity was most heavily occupied and where more seats remained open. The 73.3% RDU–LHR figure sits at the bottom, while Chicago–Athens leads at 93.62%, with the airline’s overall transatlantic average standing at 85.01%.
