 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 distance ice skating tour.