Pope Francis warned that the global economic crisis risked creating a generation blighted by youth unemployment as he flew to Brazil for his first overseas trip as head of the Roman Catholic church.

On board the aircraft taking him directly from Rome to Rio de Janeiro on Monday for week-long World Youth Day celebrations, the pontiff said society needed to become more inclusive in order to avoid young people becoming isolated.

"The world crisis is not treating young people well … We are running the risk of having a generation that does not work. From work … comes a person's dignity," he told reporters. "When we isolate the young … we strip them of the possibility of belonging and the young have to belong."

As he headed to a country which has recently been convulsed by protests against creaking public services and political corruption, Francis said the message he wanted to convey during his trip was a need for inclusivity. "We need to make an effort to bring everyone into society," he said, also highlighting the damage done to elderly people by what he labelled "a disposable culture".

Earlier, the Argentinian pontiff carried his own bag on to the Alitalia flight which will ferry him to his home continent.

After greeting the Italian prime minister, Enrico Letta, on the tarmac at Rome's Fiumicino airport, the 76-year-old boarded the A330 Airbus shortly before 9am local time (0700 GMT), shaking hands with flight attendants and appearing to wave goodbye from inside the plane.

In keeping with his trademark style, he wore a plain white cassock and carried his hand luggage – a black leather briefcase – with him up the steps and into the plane.

The papal aircraft, carrying both Vatican officials and journalists, is due to touch down in Rio de Janeiro at 4pm local time (1900 GMT). The Catholic church's first Latin American leader is expected to speak at a welcome ceremony at around 5pm, and then meet Brazil's president, Dilma Rousseff.

He will spend the week visiting various sights in the world's most populous Catholic country as part of the World Youth Day (WYD) celebrations.

Appointments include celebrating mass at Aparecida, a religious shrine in São Paulo state, a visit to a favela in Rio that was recently "pacified" by police, and speaking to huge crowds on Copacabana beach.

High security will be in place throughout in Brazil. Officials have had to comply with Francis's desire not to ride in a bulletproof popemobile but in two open-top Jeeps from which he can easily descend to meet the faithful.

On Monday morning, Francis posted a message on his @pontifex Twitter accounts that read: "I am arriving in Brazil in a few hours and my heart is already full of joy because soon I will be with you to celebrate the 28th WYD."

In a message to the Italian president, Giorgio Napolitano, prior to his departure, the pope said he was going to encourage the young people at the WYD "to be witnesses of hope and makers of peace".