The arrest took place on the runway of the Valencia airport Manises on Tuesday, according to Spanish newspaper El País.

The man was arrested in the cockpit just before departure to Amsterdam, planned for 2.30 p.m., upon a request from the justice authorities in Argentina. The pilot, identified as Julio Alberto P., holds both Dutch and Argentinian citizenship.

He is wanted for questioning in four probes of more than 1,000 deaths during his time as a pilot at the Navy Mechanics School, a notorious torture center in Buenos Aires, Spanish police said. The Argentinean junta under Jorge Videla got rid of opponents by throwing them from airplanes and helicopters into the Atlantic Sea and Argentine rivers, hence the name vuelos de la muerte.

The pilot's arrest led to a long delay for passengers as the airline had to fly a new crew in from Amsterdam in order to get the plane back to the Netherlands. Passengers say they had no idea what was going on; Transavia only said that the flight had been delayed due to the fact that the pilot was unable to carry out his duties.

The flight was to be the pilot's last before he was set to retire. A Transavia spokesperson told De Volkskrant he had never raised suspicion while working for the airline since 1988. "He has worked for Transavia for a long time. If someone has a Dutch passport, we have no reason to doubt them."