The aircraft entered Portuguese airspace at 09:12 and was escorted by two F-16 fighters until arriving at the base of Figo Maduro, in Lisbon, where it landed 17 minutes ahead of schedule.
Pope Francis is to be welcomed at the airport by the President of the Republic, Marcelo Rebelo de Sousa.
According to the program given to the journalists who are part of the papal flights, after landing, the papal nuncio, Ivo Scapolo, and the head of protocol board the aircraft, to greet Francis who descends in the elevator.
The Pope is to be received by the President of the Republic and two children, in traditional costumes, who offer Francisco flowers.
The two heads of state cross the halls of honor, greeting the delegations, and head to a reserved area of the hangar, where they have a brief meeting, according to the program.
After the official reception, a welcoming ceremony takes place at the main entrance of the Palace of Belém, where, at 11:15 am, the Pope pays a courtesy visit to the President of the Republic.
This is followed by a meeting with authorities, civil society and the diplomatic corps, at the Centro Cultural de Belém.
In the afternoon, at 16:30, Francisco has a meeting with the President of the Assembly of the Republic, Augusto Santos Silva, followed, 15 minutes later, by another with the Prime Minister, António Costa, both at the Apostolic Nunciature.
The last point of the first day of the Pope's trip to Portugal is the afternoon prayer (Vespers), which he will preside over, and which brings together bishops, priests, deacons, consecrated men and women, seminarians and pastoral agents, at the Jerónimos Monastery, starting at 5:30 pm.
More than a million people are expected in Lisbon for WYD, which started on Tuesday and ends on Sunday.