Five months from retirement, EgyptAir co-pilot Gameel Batouti, a veteran in the sky, was scheduled to fly part of the New York-to-Cairo route. A few days before Flight 990 took off Oct. 31, Batouti's brother-in-law asked him whether flying over water made him nervous. "We see our deaths every day over the ocean," the co-pilot replied.

Whether that remark was a bit of quotidian poetry or a forecast of doom may never be known. But Batouti has now emerged as the center of a complex and diplomatically dicey investigation into the fate of Flight 990.

Every conceivable aspect of Flight 990--its timing, its mechanical health, its passengers and now especially its crew--has been under microscopic inspection since the jet plummeted through the night sky over the North Atlantic on Halloween morning. With no survivors, a shattered fuselage, no obvious evidence of mechanical problems and the usual hunger for answers that follows an air disaster, the investigation now centers on the horrible possibility that one man--someone entrusted every working day with hundreds of lives--committed one of the largest and most cold-blooded mass slayings in history.

There remain more questions than answers about the crash. The possibility of pilot intent is based on a few lines of dialogue retrieved from the cockpit voice recorder and a preliminary reconstruction of the sequence of events onboard the doomed flight. But no other hypothesis has emerged from the federal probe and as frightening a scenario as an intentional downing may be, it has happened before.

As best as investigators and reporters can tell at this point, this is what happened on EgyptAir 990:

A Long and Late Flight

The flight, as ever, was to be a long one, from night into day and on into the next evening. Eleven hours from New York's JFK Airport to Cairo, plus EgyptAir had a history of tardiness. The Boeing 767 that would become Flight 990 was late on its way to the United States, late getting to Los Angeles, and now--Saturday, Oct. 30--after having to change two tires at Los Angeles International Airport, it was four hours late on its return from California to JFK.

The Boeing 767 was delivered new to EgyptAir in 1989, powered by two Pratt & Whitney engines. The plane had proven reliable and efficient; it had logged 33,219 hours of flight time, almost as many hours as the combined tally of its experienced command crew of four captains and first officers.

EgyptAir generally carried a crew of four on its transatlantic routes, but there were also two extra pilots on Flight 990 on a training course to familiarize them with the route across the ocean.

One of those extra crew members, co-pilot Hesham Omar, was supposed to have gone home earlier that week, on Oct. 27, but some of his crew pals persuaded him instead to fly out to Los Angeles, hang out for a couple of days and then head back to Cairo on Flight 990. After all, this was his first time flying the Atlantic route--part of his transatlantic training program--and he had wanted to pack in some sightseeing, first in New York, then out West.

Flight 990's pilot, Ahmed Mahmoud Mohamed Habashy, was one of the airline's most senior and respected fliers, a veteran of 35 years in the skies.

But the crew member who was closest to retirement was Batouti, 59, who regularly commuted to the United States to obtain treatments for his 10-year-old daughter, Aya, who suffers from lupus, a disorder of the immune system. Those treatments would cost less than $2,000 a year, officials at UCLA Medical Center said. Batouti, a former Egyptian Air Force pilot, faced mandatory retirement in March.

Batouti, who investigators now think was the man who sent Flight 990 into its fatal dive, had long been frustrated that he never made the rank of captain, but relatives said he remained devoted to flying and to safety.

Thirty-two passengers traveling through to Cairo had boarded Flight 990 in Los Angeles; an additional 167 joined them in New York. Just one passenger got off the plane in New York--Edward McLaughlin, who had conducted a seminar in Los Angeles for EgyptAir's employees there on coping with loss and bereavement in a plane crash.

Now, with pilots and attendants, there were 217 people on board--just shy of the 767's capacity.

Passengers With Goals

The trip to Cairo was routine for some, the highlight of a lifetime for others. There were Americans, Egyptians and others--the first black firefighter in Rochester, N.Y.'s history, a couple in their seventies celebrating their first wedding anniversary. Four women from Southern California who played cards together every Thursday night had been planning their three-week vacation in Egypt for almost a year. Two couples from the San Diego area were going to ride camels, climb the pyramids and ride down the Nile.

Before they left Baltimore, four Egyptian exchange students had one last request for their new American friends: Please, can we go shopping just one more time? It was late Friday night, after 11, and the only place still open was Wal-Mart.

So the four of them--15-year-old Fawzy Sameh, 19-year-old Sameer Walaa and the two 13-year-olds, Badaway Ahmed and Hossameldin Gihad--joined their friends from Dunbar High School in Baltimore for a midnight shopping spree. A few hours later, the Egyptians lugged seven suitcases full of last-hour purchases over to Baltimore-Washington International Airport for the flight that would connect them with Flight 990.

They would be one of several groups on the plane--including several dozen old folks starting out on an Elderhostel trip and a contingent of Egyptian military officers--at least 25 of them. Abdel-Rahman Amin, owner of a coffee roasting factory, and his wife were eager to get home to Cairo in time for the birth of their 11th grandchild. Co-pilot Adel Anwar was so eager to get back to Egypt and prepare for his wedding that he had swapped shifts with a colleague.

The flight finally took off at 1:19 a.m. on Oct. 31, 2 hours and 19 minutes late. Takeoff and ascent were normal. Flight 990 began climbing to the southeast. At about 120 miles out, the plane was vectored to the northeast and settled in for a long overwater flight at 33,000 feet.

During long overseas legs, life can be boring for a pilot. There are some routine duties, but in an era of computer-driven jets, a pilot is mainly a well-trained passenger and observer.

At 1:43 a.m., the plane made a routine radio transmission to air traffic control.

Early in the flight, according to sources familiar with the investigation, Batouti, the relief co-pilot, entered the cockpit and requested to fly, even though he was not scheduled to take over until far later in the trip. Batouti was given the co-pilot's chair.

Half an hour into the flight, with many of the passengers drifting off to sleep and the plane at cruising altitude, Capt. Habashy got up, exchanged a few words with the co-pilot and left the cockpit, perhaps to use the bathroom, perhaps to get some coffee.

Co-Pilot Alone at the Controls

The co-pilot was now alone in the cockpit, sitting in the right-hand seat, the cockpit voice recorder suggests.

Sometime in the next five minutes, the co-pilot--now believed to be Batouti--recited a fragment of a Muslim prayer: "Tawakilt ala Allah," which has been variously translated as "I entrust myself to God" and "I put my faith in God's hands."

Although federal investigators have not released any transcript of the cockpit remarks, various investigators and congressional sources have relayed the dialogue to reporters in similar yet distinctive variations.

According to government sources, the co-pilot then says, "I have made my decision." A former CIA official said that the emerging hypothesis of an intentional downing is heavily based on that "decision" quotation.

Whatever the precise words, the actions that followed are devastating in their clarity.

At 1:49 a.m. and 45 seconds, investigators now believe, the co-pilot clicked twice on the red button on his control column, switching off the autopilot. If some defect had shut off the autopilot, or if the autopilot sensed a situation it couldn't handle, such as severe turbulence, an alarm would have sounded. None did.

Eight seconds later, the co-pilot pushed his control column forward, tilting the plane over into a dive. The plane's tail raised up; the nose pointed down. Fourteen seconds later, the dive was so steep that Flight 990 reached a zero-gravity state, which means that its passengers felt weightless--a condition that lasted about 20 seconds.

At almost the same time, Flight 990 surpassed its maximum allowed speed and plummeted at up to 94 percent the speed of sound. A warning alarm sounded and because of the zero-gravity state, engine oil pressure dropped.

Somewhere in this chaos, Capt. Habashy, presumably alarmed by the sudden descent, returned to the cockpit--the opening of the door is captured on the cockpit voice recorder. By some accounts, he got back into his seat and said, "What's going on?" or "What's happening?" Moments later, the same voice: "Pull with me! Pull with me!"

At 1:50 a.m. and 22 seconds, two odd things happened.

Two devices on the tail began to point in opposite directions--one commanding the plane to dive, the other positioning it to climb. The "climb" device was being controlled from the pilot's seat, while the "dive" device was directed from the co-pilot's side.

These left and right elevators, which normally operate in tandem to control the craft's up and down movements, split--apparently the result of two pilots pulling and pushing hard in opposite directions on their control columns.

Flight 990 kept diving, kept picking up speed, plummeting toward the Atlantic.

At almost the same moment, someone shut down the engines, a deliberate step that requires pulling up a shield and pulling a switch. It cannot be done accidentally.

In the final seconds before the flight's recorders stopped working, someone deployed the plane's speed brakes, panels mounted atop the wing that can help a plane descend without overspeeding. Those familiar with aerodynamics say that such a maneuver would only cause the plane to descend even more forcefully and make it difficult to climb. The speed brake handle is located on the pilot's side of the cockpit.

Nonetheless, for a few seconds at least, Flight 990 seemed to be coming out of its dive, investigators said yesterday.

A Climb, Then a Final Plunge

But not for long. Perhaps eight seconds after the engine shutdown, the recorders and the plane's altitude-reporting transponder stopped working. But radar shows the airplane climbing back to about 24,000 feet. It is not clear whether the climb back up was the result of the pilot's attempt to save the flight or simply the aircraft's natural inclination to fly.

The climb didn't last long. Before 2 a.m., Flight 990 stalled, plunged and broke apart. The debris scattered about 60 miles off the Massachusetts coast. A few remains were found of the 217 people who flew that night. There was never so much as a distress call from the plane.

At the airport in Cairo, hired taxi drivers held aloft signs with the names of passengers who would never arrive.

Gameel Batouti, who like any other employee of EgyptAir would be covered by $100,000 in insurance to any worker who dies in flight, according to one pilot, left behind his wife and five children, including Aya, the 10-year-old lupus sufferer. "She was everything to him," the co-pilot's brother-in-law, Essam Dahi, said. "Only God will be able to give her the kind of love her father offered."

The investigation continues. In Cairo, where news reports and cafe conversations variously blame the crash on the United States, Israel and other phantoms, Didi Farid, sister of pilot Habashy, says, "They speculate. Everybody speculates. They don't know. Where is the truth? They don't know."

Staff writers Raja Mishra in Baltimore, Rene Sanchez in Los Angeles, Lynne Duke and Liz Leyden in New York, and Lorraine Adams, Vernon Loeb and David A. Vise in Washington contributed to this report.