In spite of the cloud of ash that led to the cancellation of flights in Portugal over the weekend, plans for the Holy Father's pilgrimage to Portugal remain firm. The Holy Father will be in the country on Tuesday morning to complete a packed four-day trip, but the culminating event for him is the stop in Fatima, with which he has a long history.

Pope Benedict's trip to the western European country will take place from Tuesday to Friday, beginning with a visit to the country's capital Lisbon, then to Fatima and finally to the city of Porto.

Vatican spokesman, Fr. Federico Lombardi, said over the weekend that for the moment plans would not be altered due to the cloud of ash from Iceland's Eyjafjallajökull volcano. The debris shut down airports in much of Portugal on Sunday and hundreds of flights were canceled in both Lisbon and Porto.

These airports have since been re-opened, but the threat that flights could again be suspended remains, according to the Portuguese press. The contingency plan is reportedly to direct the Pope's plane to Faro, over one hundred miles to the south.

The Holy Father is scheduled to arrive in Lisbon by plane at 11 a.m. local time on May 11.

Expressing his joy at the coming journey, Pope Benedict asked for prayers and called the visit to Fatima the trip's highlight before Sunday's Regina Coeli prayer in St. Peter's Square.

Cardinal Jose Saraiva Martins, prefect emeritus of the Congregation for the Causes of Saints, told Vatican Radio over the weekend that the Holy Father has a special relationship with the Marian shrine.

"There is a great bond between Benedict XVI and Fatima," he said. "This is because, among other things, Cardinal Ratzinger has already been in Fatima to preside over the world pilgrimage, which saw hundreds of thousands of people."

Additionally, Cardinal Saraiva Martins remembered a conference then-Cardinal Joseph Ratzinger gave at the Catholic University of Porto on the Fatima apparitions, his role in preparing the publication of the third "secret" of Fatima as well as the document read at the end of the beatification Mass for Jacinta and Francisco 10 years ago. The document was prepared by the Congregation for the Doctrine of the Faith, headed at that time by Cardinal Ratzinger.

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Speaking to the Italian bishops' Avvenire newspaper, the Patriarch of Lisbon, Cardinal Jose da Cruz Policarpo, said that ever since his election the Pope "has desired to come to Fatima." He also told the paper that the Holy Father would likely explain his deep connection to the Marian shrine during his visit.