Pope Francis embarked on his fifth visit to Africa on Tuesday, where he will first visit the Democratic Republic of Congo and then South Sudan to plead for peace in the countries, both wracked by decades of stubborn conflict.
Thousands of well-wishers were expected at Kinshasa's Ndjili airport to greet the 86-year-old pontiff, whose plane was due to arrive at around 3:00 pm (1400 GMT).
It is the first time since 1985 that a pope has visited DRC, a desperately poor country of close to 100 million people, 40 percent of whom are Catholic.
The six-day trip to DRC and South Sudan had been planned for July 2022, but postponed due to the pontiff's knee pain that has forced him in recent months to use a wheelchair.
He boarded the plane in Rome via an elevator.
Security concerns were also said to play a role in delaying the trip, and a stop in Goma in DR Congo's east, where dozens of armed groups operate, is no longer on the itinerary.
"I would have liked to go to Goma too, but with the war, you can't go there," the pope told reporters on the plane.
On Sunday, he had offered his greetings "with affection to those beloved peoples who await me".
"These lands, situated in the centre of the great African continent, have suffered greatly from lengthy conflicts," he said after his Angelus prayer at the Vatican.
He lamented "armed clashes and exploitation" in DR Congo, and said South Sudan, "wracked by years of war, longs for an end to the constant violence".
As the papal plane flew over the Sahara, the pope held a prayer for "all the people who, searching for a little well-being, a bit of freedom, crossed (the desert) and didn't make it".
He recalled how many people arrive in north Africa hoping to cross the Mediterranean into Europe, only to find themselves "taken to camps, and suffering there. Let us pray for all those people".
- Victims of violence -
Despite its vast mineral wealth, some two-thirds of DRC's population live on less than $2.15 a day, while violence plagues the eastern provinces.
The Tutsi-led armed group M23, which Kinshasa alleges is backed by neighbouring Rwanda, has been conquering large swaths of territory in North Kivu province.
The region has also seen a wave of deadly attacks blamed on the Allied Democratic Forces (ADF), a group the Islamic State claims as an affiliate, including a bomb blast at a Pentecostal church this month that killed 14 people.
Following a welcome ceremony at the Kinshasa airport, Francis will be received at the presidential palace by President Felix Tshisekedi.
The Argentine pontiff will then make his first of a dozen speeches during the trip, addressing authorities, the diplomatic corps, and representatives of civil society.
"He can deliver a strong message to politicians by addressing the issue of corruption" ahead of a general election scheduled for December, said Samuel Pommeret with Catholic humanitarian group CCFD-Terre Solidaire, which operates in the area.
Tens of thousands of people are expected to attend a prayer vigil Tuesday evening at N'dolo airport ahead of a mass on Wednesday morning, which is tipped to draw more than a million faithful.
Papal memorabilia was already selling well in Kinshasa in the run-up to the visit, with Elisabeth Akwete, 66, among those buying a calendar bearing the image of Francis.
"It's a joy to have the image of the head of the Church at home," she told AFP.
During his visit to DRC, the pope will also meet victims of violence as well as members of the clergy and charities operating in the country.
- Pilgrimage of peace -
On Friday, Francis will travel to Juba, the capital of South Sudan, also one of the world's poorest countries, that has lurched from one crisis to another since gaining independence in 2011.
It suffered a brutal five-year civil war, while continued conflict between rival ethnic groups exacts a terrible toll on civilians.
The pope will be joined in Juba by the Archbishop of Canterbury, Rowan Williams, and the leader of the Church of Scotland, on what he has called "an ecumenical pilgrimage of peace".