ABOARD THE PAPAL PLANE — As he flew to Brazil on his first international trip as pontiff, Pope Francis voiced concern today about an entire generation of youths growing up jobless and isolated.

Mammoth crowds are expected to attend a Mass he will celebrate on Rio’s Copacabana beach during his trip to his home continent.

Francis also will meet with legions of young Roman Catholics converging on Rio for the church’s World Youth Day festival, believers whose behavior so far hasn’t been typical of the typical tourists in this seaside Sin City known for hedonistic excess.

The pontiff is expected to arrive in Rio de Janeiro this afternoon.

During his flight from Rome, Francis warned about youth unemployment in some countries in the double digits, telling about 70 journalists aboard the papal plane that there is a “risk of having a generation that hasn’t worked.” He said, “Young people this moment are in crisis.”

Francis also expressed concern about the elderly, saying older people should not be isolated or “thrown away ... as if they had nothing to offer us.”

“A people has a future if it goes forward with bridges: with the young people having the strength to bring it forward and the elderly because they have the wisdom of life,” the pope said. The elderly have, he said, “the wisdom of history, the wisdom of a nation, the wisdom of a family, and we need this.”

During his visit, more than 1 million people are expected to pack the white sands of Copacabana to celebrate Mass with the 76-year-old Francis.