High above the Iraqi desert, Lt. Cmdr. Todd Wilson says, antiaircraft fire flashes a green tinge in his night-vision goggles, and sometimes a burst gets so close that, for a moment, it washes out his entire field of view.

Patrolling the "no-fly" zone in southern Iraq, Wilson and the other top guns of this massive aircraft carrier have gained a foretaste of what war would feel like: sporadic and ineffectual resistance. But that may just be a hint of the full flavor to come. "There's always the chance that they're hiding more capability," Wilson said. "We fully expect to see more of a defense than we're seeing now in southern Iraq."

They may soon find out. If President Bush orders an invasion of Iraq, it will fall to the air wings of the Constellation and its fellow carriers to pave the way. With Saudi Arabia refusing to allow offensive airstrikes from its territory and Turkey balking at a request by U.S. officials to conduct the full-scale operations they envisioned, Navy aviators rocketing off the decks here in the Persian Gulf may bear a greater burden this time than during the air war of Operation Desert Storm in 1991.

The role seems to particularly suit the venerable Constellation, nicknamed "America's flagship," and, at 41, the Navy's second-oldest vessel. In one of its earliest deployments, the Constellation launched the first naval strikes against North Vietnam in response to reports of hostile fire in the Gulf of Tonkin. Now in its final deployment before being mothballed, it could launch the first strikes against President Saddam Hussein's Iraq.

"It's not out of character for us to be involved in a conflict," said Capt. John W. Miller, the ship's commander. "This is not a role that we're unfamiliar with."

The Constellation will be the vanguard of a formidable armada. A second U.S. carrier is now steaming toward the gulf and a third probably will join them. The USS Harry S. Truman has been stationed in the eastern Mediterranean Sea and may also be joined by two others.

In addition to hosting 70 to 80 attack aircraft, each carrier commands a battle group of eight to 10 ships, including cruisers, destroyers and frigates. Other vessels, including those bearing amphibious strike forces, jockey for space in the crowded gulf.

On the expansive flight deck of the Constellation, stretching the length of 31/2 football fields, pilots and crews scurry around as if on war footing. The carrier launches perhaps 80 or more sorties per day, roughly 25 days per month, most of them heading toward the skies of Iraq, where they enforce restrictions on Iraqi aircraft imposed after the 1991 Persian Gulf War.

Over the past few months, crews have seen a dramatic escalation in hostilities in the southern no-fly zone, a quasi-war before the war. U.S. pilots say they have been shot at more frequently, and they have struck back with increasing firepower and latitude. Iraq does not recognize the legitimacy of the no-fly zones, saying the U.S. planes are violating its airspace.

"To know that people in anger are shooting at you, it's obviously more than a wake-up call," said Wilson, 34, a Californian who has been fired upon in his F/A-18 Hornet several times since the Constellation returned to the region in December. "It lets you know how serious it is."

The patrols have served as practice runs for U.S. pilots who may soon go to war. By now, Navy officials say, every tactical aviator in the fleet has served at least one tour of duty over the no-fly zones. During the Gulf War, it was all unfamiliar territory; this time, they would know the landscape, its bridges, cities and air-defense installations.

"We've been here now for a long, long time. We're flying over Iraq every day," said Capt. Mark I. Fox, commander of the carrier air wing and the first Navy pilot to shoot down an Iraqi plane in the Gulf War. "So the war, if it came, would begin much closer to Saddam's doorstep than Desert Storm did. [In] Desert Storm, we had to take down all of his integrated air defense, we had to take down all of his early warning radar, we had to take down all of that stuff."

Now, much of that is gone.

And as Iraq's military capacity has deteriorated, the U.S. arsenal has improved. For all the publicity about smart bombs during the Gulf War, they represented just a fraction of the explosive power felt by Iraq. In any future war, smart bombs would dominate the payloads.

As a result, the calculations have flipped. During Desert Storm, success ratios were measured by how many sorties it took to eliminate a target. This time, missions would be judged by how many targets are destroyed by each plane. "That's a revolutionary change," Fox said. "That increases your firepower dramatically."

It also increases the potential for complacency, something commanders aboard the Constellation must guard against. While the Iraqis have never shot down a manned U.S. warplane over the no-fly zones, pilots here took grim note of the enemy's success in blasting an unmanned Predator drone out of the sky in December.

And on the desk in his cramped stateroom, Fox has a "Free Scott Speicher" bumper sticker reminding him of his friend, Michael Scott Speicher, who was shot down the first night of the Gulf War and, according to U.S. intelligence reports, may be captive in Iraq.

Fox was among the pilots taking off today for Iraqi skies. The flight deck buzzed with activity even before the sun crept above the hazy horizon. Mechanics, signal officers and aircraft directors prepared the day's flights and strapped on the bombs. Gusty winds blew the distinctive stench of jet fuel across the 4.5-acre deck. Most of the crew members handling the multimillion-dollar machines were too young to drink legally, some still covered in pimples.

By 7:45 a.m., the first planes were ready to go. One after another, they were hurled off the deck by steam-powered catapults, accelerating from zero to 150 mph in two seconds. In the first 15 minutes, 13 planes were launched.

Within hours, they began returning, dropping out of the sky to catch one of four trap cables that brought them to a halt within 300 feet, even as other planes were still taking off. With the exception of a short afternoon break, the hectic cycle would continue through 11 p.m.

Keeping track were 40 or 50 sailors and officers in the Combat Direction Center, deep in the bowels of the 18-deck ship. The windowless center, with an array of computer screens and radar displays bathed in blue light, allowed the command crew to monitor all aircraft, surface ships and submarines in the area, including commercial traffic.

"The main thing about the Navy is, we don't have to ask for permission to operate in your nation's air base," said Cmdr. Mike Daly, the combat center's chief officer. "We're in international water. It's a great tool to have."

But the next war would test the limits of this particular tool. After four decades, the Connie, as its crew calls it, is on its last legs, scheduled to be decommissioned in May. Only the USS Kitty Hawk is older, by nine months. Replacing the Constellation will be the new USS Ronald Reagan, a nuclear-powered vessel that will not need the refueling that takes the Constellation out of action for three hours each week.

The Connie shows its age. The lights sometimes flicker, the hot water is not always so hot. But Miller said it holds up well and insists that, if war comes, it can keep up with the newest of carriers. "Effectively," he said, "we are every bit as capable as they are."

An air crew aboard the USS Constellation, stationed in the Persian Gulf, prepares an F-14 Tomcat for a mission over the "no-fly" zone in southern Iraq.