Willem-Alexander is an avid pilot and has said that if he had not been a royal, he would have liked to be an airline pilot so he could fly internationally on large-sized aircraft such as the Boeing 747.
During the reign of his mother, he regularly flew the Dutch royal aircraft on trips.
However, in May 2017, Willem-Alexander revealed that he had served as a first officer on KLM flights for 21 years, flying KLM Cityhopper's Fokker 70s twice a month, even after his accession to the throne.
Following KLM's phased retirement of the Fokker 70, he began training to fly Boeing 737s.
Willem-Alexander was rarely recognized while in the KLM uniform and wearing the KLM cap, though a few passengers recognized his voice, even though he never gave his name and only welcomed passengers on behalf of the captain and crew.

Using the name "W. A. van Buren", one of the least-known titles of the House of Orange-Nassau, he participated in the 1986 Frisian Elfstedentocht, a 200-kilometre-long (120 mi) distance ice skating tour.
He ran the New York City Marathon under the same pseudonym in 1992.
Willem-Alexander completed both events.
Willem-Alexander is an avid pilot and has said that if he had not been a royal, he would have liked to be an airline pilot so he could fly internationally on large-sized aircraft such as the Boeing 747. During the reign of his mother, he regularly flew the Dutch royal aircraft on trips. However, in May 2017, Willem-Alexander revealed that he had served as a first officer on KLM flights for 21 years, flying KLM Cityhopper's Fokker 70s twice a month, even after his accession to the throne. Following KLM's phased retirement of the Fokker 70, he began training to fly Boeing 737s. Willem-Alexander was rarely recognized while in the KLM uniform and wearing the KLM cap, though a few passengers recognized his voice, even though he never gave his name and only welcomed passengers on behalf of the captain and crew.
Using the name "W. A. van Buren", one of the least-known titles of the House of Orange-Nassau, he participated in the 1986 Frisian Elfstedentocht, a 200-kilometre-long (120 mi) distance ice skating tour. He ran the New York City Marathon under the same pseudonym in 1992. Willem-Alexander completed both events.
Willem-Alexander of the Netherlands