It was only as the doors were about to close on Air Force One at the Cairo airport that I realized Richard Nixon was not aboard.

He had been in our motorcade from the War Memorial, where Anwar Sadat's funeral had been held, to the airport where the U.S. presidential plane was parked alongside others carrying a galaxy of the world's mighty--the Royal Air Force ship used by Prince Charles, the French craft that transported President Mitterrand, the Norwegian that held Crown Prince Harald, the North Korean that brought I know not whom.

Now Nixon had disappeared. Secretive to the end, I thought.

The 37th president, we understood from the 38th, Gerald Ford, was going to Saudi Arabia on a private trip to confer with the Royal House of Saud.

Two of the three presidents who had flown to the Mideast as delegates at the funeral were on their way back home. Only Nixon stayed behind to talk with Arab leaders. Officially, the United States greeted that news with an expression of diplomatic good wishes for his journey while stressing its private, unofficial nature.

At the same time, how appropriate in the continuing Richard Nixon story. Here he was, back in the full glow of presidential spotlight as an official state funeral emissary for the first time since he became the modern version of a man without a country, then off on a special, albeit personal, mission.

What greater repatriation, what ultimate way back from Elba, than to perform as a peacemaker, whatever lack of official sponsorship, at so critical a juncture in the Mideast?

I say that not to open old wounds or denigrate the former president, but because of all the figures who gathered at Sadat's funeral his was the most extraordinary. For the Americans particularly, his presence hung over that assemblage like Banquo's ghost.

In person, Nixon now looks more like a caricature of himself, a man in the Nixon mask: his frame seems to have shrunk, and his head grown larger. The jowls and nose are more pronounced, and his face bears a distinctly orangish cast.

But it's more than the physical look that stirs a reaction. The circumstances of his public life evoke a special troubling memory among those who see him. What's more, Nixon knows it.

The time: Friday night. The scene: the dining room of the El Salam Hotel. The occasion: a private dinner for the official American delegation hosted by U.S. Ambassador Alfred Atherton Jr.

I was not present, but many who were gave the same account of what happened:

Each of the three former American presidents spoke extemporaneously, and each was in character.

Jimmy Carter's remarks had a religious flavor, Ford's an earnest one, and Nixon's a more rambling, discursive tone.

Nixon's theme was of paying tribute to the people who had made the trip successful. He praised the Foreign Service, he gestured to the waiters standing at the back and thanked them, and then he made a remark both riveting and revealing.

It wasn't the famous people who deserved credit for making this trip successful, or even the infamous ones, he said.

That self-deprecating and unmistakable reference to his own political and personal trauma wasn't the only time others present felt Nixon's sensitivity about how he was viewed.

Let it be said that Nixon was courteous and gracious. He was deferential toward the other dignitaries, charming in conversation and remembrance of trips past. (Once, though, a fellow passenger said, he "zinged" one of his fellow presidents with a remark without the recipient realizing he had received a zinger.) And clearly--and understandably--he had every reason to feel a special emotion as an American emissary. There was both a poignancy and a fascination at seeing him standing at attention with the other presidents on the steps of that plane, taking the Egyptian salute on their Cairo arrival. God knows what hurts he must hold inside, or what thoughts his return to that ceremonial public duty must have prompted.

That trip brought a host of other vivid impressions, not least those first moments back on the presidential plane just before we learned the news about Nixon's absence.

Everyone, I think, felt a sense of emotional release and responded in kind.

Rosalynn Carter, marveling at Jehan Sadat's composure only four days after her husband's assassination and at her determination to return to the scene of his murder as his widow: "She sat in his chair," Mrs. Carter said intensely, referring to the fact that at the funeral Mrs. Sadat had occupied the very chair her husband was using when he was slain . . . .

Strom Thurmond, moving to the rear of the plane, taking off his black coat, then his white shirt and tie, and exposing a bulletproof vest, a white fabric chemise, fastened in the front by Velcro straps. He had been urged to wear it by the Secret Service, he said in his South Carolina drawl, because as president pro tem of the Senate he is third in presidential succession . . . .

Jim Wright of Texas, the House majority leader, whose smiling demeanor and thick white eyebrows, which curl to sharp points, give him a pixie-like appearance, wandered by, saw that scene with Thurmond, and acknowleded in his southwest twang that he, Wright, hadn't worn a bulletproof vest. He said drolly, in mock astonishment, "I thought he Thurmond was a man of iron."

But it was Nixon who made the greatest impression.

On the long flight back, Rosalynn Carter offered what she called "the headline on the trip." It was, as she said, "It took Anwar Sadat to bring together Richard Nixon, Jimmy Carter and Gerald Ford."

Another headline could be: Through the agony of Anwar Sadat, could come the redemption of Richard Nixon.