By Justin Udo, Steve Patterson

PHILADELPHIA (CBS) – Mayor Michael Nutter and other delegates are off on another trip to Rome to discuss logistics for the World Meeting of Families happening this Fall in Philadelphia.

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Mayor Nutter says in person meetings to hammer out the details of the event are key:

“There are only so many things you can do over the phone or over the internet.”

He says during this trip they must make sure all of the parties responsible for security are on the same page:

“This is essentially a secret service event.  That’s of course the federal government, the Philadelphia Police Department, State Police, SEPTA Police, Vatican Police, Italian Government Police and the Swiss Guard who are personal protectors of Pope Francis. All those agencies have to work very very well together.”

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Nutter says they must make sure Philadelphia is totally secure for the Pope’s visit in September:

“It will be probably some of the most intense 48 hours that this city has experienced in a while, that’s our responsibility, we take it very seriously.”

“We’ll be meeting with the pontifical council for the family who’s our partner in the Vatican, and also our group that plans the Holy Father’s foreign trips,” adds Bishop John McIntyre with the Archdiocese of Philadelphia.

The Mayor says while in Rome, he does not expect to personally meet with the Pope:

“We’ll be talking to the pontifical council on the family, we’ll be talking with other Vatican officials about this event.”

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The flight left around 6:30 p.m. Sunday. Nutter and the other delegates from the area are expected to return from their trip Friday.