The smaller man with his back to us, in the beige cardigan sweater, gesturing with his right hand, is the 39th president of the United States, Jimmy Carter. Standing to his right, in dark suit and blue sweater, his long profile with pronounced nose and jowls instantly familiar, is the 37th president of the United States, Richard Nixon. Completing the circle, and appearing more casual, in red sweater and ruddy face, is the 38th president of the United States, Gerald Ford.

In office they suffered disgrace, defeat, rejection.

Now, standing there in the forward cabin talking animatedly among themselves, they appear to be finding reason to bury the hurts of the past as they pay tribute to someone that binds them all together.

Thus in death Anwar Sadat of Egypt seems to have accomplished what America has been unable to achieve in much of its recent political past. His funeral provides a unifying theme that eases the sense of failed presidencies that have afflicted the United States for a generation.

After an understandably somewhat stiff and ultra-polite beginning, when protocol reigned and formalities were exchanged, their extraordinary encounter took on another character.

Carter found he enjoyed talking most with Richard Nixon. They spoke warmly of China. He was not so easy with Gerald Ford, the man he had defeated in 1976. There had been hard words exchanged and some of them lingered on.

"Oil and water, you know," he said with a slight smile.

But they had other things in common to discuss, and traded stories about meetings with Sadat, spoke of the Middle East and what lies ahead.

In the annals of the presidency there probably never has been another trip quite like this one. It was solemn and serious, filled with an aura of history and great matters of state, and also relaxed and disarming, a setting in which every participant seemed to share.

High-powered participants were not limited to the three presidents. Seldom has such a collection of people of power and egos been gathered together in so small a space.

In the words of Secretary of State Alexander M. Haig Jr., no bit player himself in the game of power, "This is quite a planeload."

The seating of the three former presidents presented a protocol challenge to the State Department, which solved it by giving the highest incumbent official, Haig, and his wife the presidential stateroom and sleeping quarters. Nixon, Ford and Carter shared what is normally the staff compartment, with the Carters at one table and Nixon and Ford across the aisle at another, with Henry Kissinger.

To Haig, the makeup of the planeload was "unprecedented" and the atmosphere aboard "electric." He said the trip to Egypt by the three U.S. presidents who had dealt most closely with Sadat was "an event of extraordinary significance," a message that signaled a strong show of support from a united America for an Egypt in time of crisis.

Something less tangible made this a special flight, and everyone knew it. It was the recognition of how much history and fate combined to place all these people together on that one airplane.

The plane itself was part of history, again theirs and the country's.

It is the same one in which the body of John F. Kennedy, the 35th president, lay after he was assassinated in Dallas and on which his successor, Lyndon B. Johnson, was inaugurated as the 36th chief executive.

And for each of the presidents, it was, once, theirs. It had carried them to summit conferences in the Caribbean and Europe, to Vladivostok and to China -- and also many times to the Middle East.

Whatever memories Air Force One stirred in their minds, they saw immediately upon entering that it was now clearly stamped as someone else's.

On the tables, alongside plates of fruits, were jars of jellybeans, just the same as you will find in Ronald Reagan's White House. On the walls were large color photographs of the 40th president at work and play -- of Reagan riding horseback, Reagan showing off his cowboy boots at his ranch, Reagan in formal attire raising his glass in diplomatic toast, Reagan as commander-in-chief aboard the deck of a carrier, Reagan in the oval office surrounded by beaming aides raising their glasses high in obvious celebration of some congressional victory.

Once aboard, they found the scene filled with other reminders of days past and power shared and lost.

There was Kissinger, secretary of state for both Nixon and Ford, himself a veteran player of the days of Middle East "shuttle diplomacy," and the man to whom Nixon submitted his resignation in 1974, doffing his coat and chatting in his shirt sleeves with his former aide, Haig.

There, moving down the plane, was the figure of Nixon, in his business suit and giving rather formal greetings.

"You're the spokesman," he said to Dean Fischer, Haig's press aide. "I've seen you on TV."

Nixon moved forward, glanced into the aft passenger compartment area housing 12 aides and the three-man press pool. He stopped, said, somewhat enigmatically, "This is all," turned and went forward away from view.

Once airborne, the early formality eased and the official delegation moved about freely. Soon Rep. Clement J. Zablocki (D-Wis.) was collecting autographs of everyone on the plane. He proudly showed the sheet of paper where each dignitary had signed beside his name on the flight manifest.

Zablocki's autograph collecting was catching. Leonore Annenberg, chief of protocol, was gathering her signatures and others passing around pages for signature included Egypt's ambassador to the United States, Ashraf Ghorbal, and his wife, Amal.

A curious tone of highly serious, and sometimes grim, conversation mingled with enjoyment of the moment developed on the long flight across the Atlantic to a refueling stop in Madrid, and on to Cairo.

Jody Powell, Carter's former press spokesman, told reporters that the three former presidents were being "especially polite" and Haig jokingly said that they were "on their best behavior."

Carter agreed. "We're getting along," he said.

After a moment of lightheartedness you would hear someone speak of terrorism or instability in the Middle East -- Ghorbal referring to the apparent breakdown in security at Sadat's assassination, or Sen. Claiborne Pell (D-R.I.) speaking of how many American ambassadors have been slain in the last 20 years. More than the number of admirals and generals we've lost in our last two wars, he said.

And there was the ever-present question of what Sadat's death means to the Middle East, and to the United States.

Haig and Defense Secretary Caspar Weinberger both spoke of speeding up delivery of certain kinds of military equipment to Egypt. They referred to Egypt's warnings of a possible Libyan threat to Sudan.

Later, Weinberger said the United States would consider the possibility of accelerating arms shipments to Egypt, especially in an emergency.

Carter took a harder line, too. He mentioned the need to send "very strong" warnings to Libya and said, "If Libya goes beyond Chad . . . the consequences will be very severe."

He added, "This is one time the United States ought to be ready to use muscle, if necessary."

But that wasn't the main burden of his message, or the other presidents'. They were there because each had been a part of the process that bound the United States and its interests closer to Egypt, and especially to the man they came to mourn.

As Carter said of their common journey, "I think the significance of it is Sadat. . . . What he meant to our country and to me personally. He was a hero to Americans."

When he learned Sadat had been killed, he said, it was one of the worst days of his life. "The only time I had that bad a day was when my own daddy died."

Watching him and the other presidents resume their conversation in what normally is the staff room -- smaller, less grand than the one occupied by Haig and Weinberger -- you could draw another point of significance about this trip.

Maybe the good will only bespoke the natural sharing of the world's most exclusive club, the presidency, but as we're now heading over the desert toward touchdown in Cairo the problems of Watergate and Vietnam and Iran and the failings of the presidency seem far away for now.

That alone is worth the price of admission for this sad journey.