Screaming would have been futile. With the wind and the waves and the rumble of the ship, Marine Lance Cpl. Zachary Mayo's puny cries would never have been heard, superiors would say later.

About all he could do after tumbling into the ocean from the deck of his aircraft carrier was watch in horror as the 81,000-ton vessel receded into the darkness, leaving him alone in the vastness of the Arabian Sea.

He might also have prayed, for the odds of his survival were next to nil. But last weekend Lance Cpl. Mayo, 20, the only child of an Osburn, Idaho, silver miner, kept his cool, inflated his uniform into a life preserver, and floated for two days and two nights until he was picked up by a Pakistani fishing boat.

Out of the blue, he telephoned his distraught father at 4 a.m. Wednesday.

"Hi, Dad," he said, "How you doing?"

"I'm doing fine," he father, Stanley, 43, replied. "Where the hell are you?"

Thus ended what the Marine Corps said was an almost unheard of man-overboard case of spunk and good fortune. "This doesn't happen," said Lt. Scott Gordon, a spokesman at Marine headquarters in Washington. Usually in such cases, "you're dead."

Mayo's extraordinary passage began early Saturday morning. An aviation maintenance expert assigned to a Marine air squadron aboard the USS America, he had left his berth to get some fresh air.

Gordon said that at the time the America was cruising in the northern Arabian Sea, which is flanked by the coasts of Oman and Pakistan.

It was not clear where on the ship Mayo had gone. But he told his father that a door either blew or was pushed open, and knocked him over the side.

"He went out to get a little fresh air," his father said. "Next thing he knows he's floating in the water."

Mayo told his father he treaded water until he got his uniform off, and then following Marine survival techniques, fashioned crude life preservers from his clothing.

"He tied knots in the legs and arms and swished them in the air and made a kind of balloon out of them," the elder Mayo said Wednesday in a telephone interview from his home. He continued treading water. And he waited.

Meanwhile back on the carrier, Mayo was discovered missing at the 7 a.m. muster the next morning. A search was first conducted aboard the carrier. And when he did not turn up, it was presumed he had fallen over the side.

Four helicopters and two of the America's escort vessels were sent to retrace the ship's overnight path. Gordon said the search was hampered because no one knew exactly when Mayo had fallen.

Later Saturday a Marine delegation visited the Mayo home to let the Marine's father and mother, Cindy, know their son was missing. The search continued over the weekend in vain. Tuesday afternoon Marines returned to the Mayo home to tell the parents that there still was no sign of Zack and the search had been called off.

But after 36 hours of floating and treading water, Mayo was picked up by the fishing vessel. The crew, which spoke no English, carried Mayo to the Pakistani port of Gwadar, near the mouth of the Gulf of Oman.

Gordon said Mayo had some trouble finding someone in authority who could speak English, but he finally made contact with officials in the city of Karachi.

And it was through them that he made his call to Idaho.

"It felt great," the elder Mayo said. "It was quite an ordeal. But we believed that God would take care of him. And with the help of God, he made it."