Another rare route is between Stockholm and Oslo. Also operated by TUIfly Nordic, this flight connects the busiest airports in Sweden and Norway with just one scheduled service for the year. Both airports are major hubs in their respective countries.

TUIfly Nordic also operates a single flight from Stockholm to Halmstad City Airport (HAD), another small Swedish airport on the North Sea coast with fewer than 100,000 residents. Despite its size, HAD offers varied destinations including long-haul options.

Smartwings Poland's rare flights include Kraków to Tirana—a connection between Poland’s second-largest airport and Albania’s main international gateway. Tirana International Airport saw significant growth after the end of communist isolationism in Albania.

Another Smartwings Poland route links Thessaloniki International Airport in Greece with Warsaw Chopin Airport in Poland. Thessaloniki is Greece’s third-largest airport while Warsaw Chopin handles over 20 million passengers each year.

The list also features Málaga–Costa del Sol Airport in Spain—one of Spain’s busiest airports—with a single Smartwings Poland flight to Warsaw. Warsaw is among the ten largest cities in the European Union and has a UNESCO-listed historic district rebuilt after WWII.

TUIfly Nordic will fly once from Antalya Airport in Turkey—a major summer tourist hub—to Billund Airport in Denmark. Billund was initially developed with funding from LEGO and has grown into an important Scandinavian aviation center.

A Smartwings Poland itinerary will connect Faro Airport—one of Portugal’s top three airports—with Warsaw on a single occasion this year. Faro can accommodate widebody aircraft arriving from transoceanic destinations.

TUIfly Nordic will operate one flight linking Lanzarote (Accerife) in the Canary Islands with Stavanger Airport (Sola) in Norway—Norway’s oldest airport now serving over four million travelers annually.

The final entry is another TUIfly Nordic service connecting Lanzarote with Halmstad on Sweden’s coast. According to aeroLOPA data referenced by Simple Flying, these flights use Boeing 737 MAX 8 aircraft configured for up to 189 passengers at full capacity.

"Interestingly, the rare flights in this selection are all flown by either Smartwings Poland (3Z) or TUIfly Nordic (6B). This sampling includes a range of destinations across the European continent, with each location sharing one thing in common: each is scheduled only once this year."

"Data from Cirium, an aviation analytics company, confirms that in 2025, each of the itineraries on the list below is only scheduled for a single occasion of service this year."

"The sampling below varies in distance from just under 400 kilometers to nearly 4,000."

"Another commonality between all ten of these rare flights is that they are served by the same variant of the 737 MAX family, the MAX 8."

"The 737 MAX has had a troubled time in the few years that it has been in active commercial service so far, yet it remains the most popular plane that Boeing makes."

"The latest iteration of the 737 family inherits the legacy of the world’s best-selling jetliner."