There are few transatlantic markets that have seen such considerable growth as the corridor between Spain and the United States of America in the past year. According to present scheduling data made available by Cirium, an aviation analytics company, 1,724 flights are scheduled on routes between these two nations in December 2025. This represents a 16% year-on-year increase compared to December 2024’s figure of 1,486.
As such, seat capacity has also risen, albeit by a slightly smaller margin of 14.9%. This reflects the fact that some of the additional flights are operated by smaller aircraft, with Iberia’s increased deployment of the Airbus A321XLR being a key factor on this front. Let’s dive deeper into the data and learn more!
Iberia Sits At The Top Of The Tree
Spanish flag carrier and IAG and oneworld member 
Iberia has the most flights and seats of any operator taking passengers between Spain and the US this December, with respective figures of 732 and 205,592. These represent huge increases of 32.6% and 25.9% compared to the 552 flights and 163,274 seats that it scheduled on this market in December 2024. Madrid (MAD) to New York (JFK) is its top route, with two daily round trips.
Other key US destinations that Iberia is serving more than daily on average from its Madrid hub are San Juan in Puerto Rico (48 rotations), Boston (46), and Miami (44). While the carrier primarily favors widebody twinjets from the Airbus A330 family for these operations, the narrowbody A321XLR also accounts for 220 flights, and has been key in unlocking East Coast growth. Ramiro Sequeira, Iberia’s Chief Production Officer, said last month:
“The Airbus A321XLR has transformed our long-haul strategy, enabling us to open new destinations and increase frequencies with unprecedented efficiency. Its range and fuel savings give us unique flexibility.”
American & Delta Are Also Big Hitters In This Market
When it comes to operators from the other side of the North Atlantic Ocean, Iberia’s fellow 
oneworld member American Airlines has the largest presence on routes between Spain and the US this month. Interestingly, its total of 432 flights on this market is exactly the same as in December 2024, although its seat capacity has risen by 5.7%. This indicates that it is deploying larger aircraft and/or those with denser cabin layouts on board.
Widebody twinjets from Boeing’s diverse portfolio of airliners are American’s planes of choice on its Spanish routes, with its coverage split between the 777 and 787 families. This month, it is serving the Madrid to JFK route once a day except for December 25, and has daily round trips from Madrid to Charlotte (CLT), Dallas/Fort Worth (DFW), Miami (MIA), and Philadelphia (PHL), as well as from Barcelona (BCN) to Miami and Philadelphia.
Elsewhere in the US, Delta is the carrier with the largest annual growth on this market, increasing its coverage by 20.2% from 213 flights in December 2024 to 256 this year. This figure is split between 62 flights with the Airbus A330-300 and 194 with the Boeing 767-400ER. Atlanta (ATL) to Barcelona has 35 round trips penciled in, while Atlanta to Madrid, New York JFK to Barcelona, and JFK to Madrid all have 31, representing a daily round trip.
Delta Air Lines Teams Up With Celebrity Chef José Andrés For Spanish-Inspired Menu
The special dishes will be rolled out on November 4.
The Best Of The Rest
United Airlines, the last of the ‘big three’ US legacy carriers, also links its homeland with Spain, albeit not to the same extent as its rivals. This month, it has scheduled 197 flights on this market (up 8.8% vs last year), with these being operated by 
Boeing 767, 777, and 787 twinjets. From Newark (EWR), it serves Madrid and Barcelona daily, with lower frequencies from Washington (IAD) to both destinations and Chicago (ORD) to Barcelona.
The final airline operating scheduled passenger flights between the US and Spain this month is Spanish carrier Air Europa, which has one service fewer than this time last year (107 vs 108). Most of these flights use the carrier’s Boeing 787s, although some are operated on its behalf by Iberojet using Airbus A330-900s. Flying out of Madrid, Air Europa offers direct passenger flights to two destinations in the US: Miami and New York JFK.
