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(CNN) - The world is preparing for what may be the largest gathering of heads of state since Winston Churchill's funeral in 1965.
The U.S. alone has an impressive commanders-in-chief collection headed there - President Barack Obama, and former presidents George W. Bush, Bill Clinton, and Jimmy Carter comprise one of the most prestigious frequent fliers clubs in the world.
"Air Force One departed Monday for South Africa where more than 90 heads of state are planning to attend Nelson Mandela's memorial Tuesday in Johannesburg. Inside, the Obamas, George W. and Laura Bush, and former Secretary of State Hillary Clinton. Former President Bill Clinton and daughter Chelsea are flying from an event in Rio, Brazil, and linking up with the rest of the club tomorrow. President George H. W. Bush, who's been in poor health for some time, won't be making the trip.
Together, they are set for an almost 20-hour flight, with only one bed on board.
Air Force One is a very intimate setting, so that's the place where you can have quieter conversation," said former presidential adviser and CNN senior political analyst David Gergen. "Once you get to one of these massive events, it's very hard to have real conversations."
These long flights, believe it or not, can forge friendships.
In 1981, President Ronald Reagan could not attend the funeral of Egypt's Anwar Sadat, so he enlisted Richard Nixon, Gerald Ford, and Jimmy Carter to attend instead. The flight was said to be initially awkward, and very long. But one notable friendship emerged, evident at Ford's funeral more than 25 years later, when Carter eulogized his longtime friend.
In 1992, Bill Clinton and President George H. W. Bush fought a bitter presidential contest. But when they traveled together to attend the funeral of Jordan's King Hussein in 1999, the ice began to thaw. Now, they're partners in philanthropy all over the world.
Such a gathering of all living presidents is typically reserved only for monumental and sad events. The journey itself holds the potential for conflict and resolution on a first-class scale.
"It's going to make a big, big difference. And the atmospherics on Air Force One with George W. Bush there with his successor - President Bush has been so reserved in making any negative comments, he's not second-guessing his successor, and I think that the Obama people really appreciate that," said Gergen.
The gang has seen more of each other than usual; the trip to South Africa will be the third time members of the so-called presidents club have met this year.
In April, the group suited up to attend the dedication of the Bush Presidential Library in Texas.
Then in August, Clinton, Obama, and Carter joined forces to honor the 50th anniversary of the March on Washington.
But for all their smiles, a stage shared by leaders can seem rather small at times.
"No former president likes to marginalized. They've always been the center of attention. And here we're going to have three formers and a current president. Four centers of attention? That's a lot to juggle," said Gergen.
So safe travels to our nation's leaders, may you get along well with your seatmate.