Changes in Flight Patterns : Airports: Increased security may be an inconvenience, but passengers don’t mind too much. They apparently would rather be safe than sorry.

The passengers who fly the commercial air routes across America these days know the war is over there. They have been told, too, that the fuse was long ago laid here at home, that an airplane or airport full of commerce-bent Americans is enticing quarry for a terrorist.

In the few days since the weightier instruments of security were uncased, and 435 American airports were ratcheted up to what federal officials call Level 4 vigilance--the FAA’s highest--travelers seem to be more comforted than discommoded by the precautions.

Along the suddenly depopulated airport concourses--now ordered emptied of tearful family send-offs and riotous welcome-homes--a silence pervades. The loudest voices come from the earnest TV tenor of Tom Brokaw, and the tape-loop announcements warning not to leave bags unattended.

Professional travelers, ordinarily so abrupt and knowing, have become docile and obliging. They are not exasperated at seat-assignment flummoxes. They do not bang heartily down the aisles, joshing the flight attendants. Planes at present appear as full as ever, yet a certain intensity, if not quite tension, crouches inside the carpeted cabins.

On a weekend flight out of Hartsfield International here, a woman sitting near the back of the plane, traveling with friends to some festive occasion, half-stood up in her seat. She took out her camera to record this moment in their odyssey. The flash flared startlingly in the dimness. Heads jerked; a stifled gasp spiked above the engine thrum. The woman winced, waggled the camera and smiled, apologetically. The other passengers turned around again. Most of them had not smiled back.

BUFFALO AIRPORT

The Dallas antique dealer was clearly rattled, and far more helpful than the security man at the end of the X-ray conveyor had asked him to be.

“It’s a boat,” he said, handing over a fragile little toy skiff. “And this is a little windup girl”--he turned a doll to front and back. “And wait, I got a blanket.” He unfurled a fringed red tartan square and splayed open a box to show the guard another toy boat.

“Thank you,” the security guard kept saying, glancing at the line building up behind him. “Thank you, sir.”

The traveler repacked his bag and headed to his gate. “Aren’t you a little nervous?” he said. “I am.” Jim Downey, 41, grew up in Buffalo, and on the first weekend of the war, flew back for his father’s funeral. “This is an international border. I was almost going to cancel my flight and take a bus. All the wackos come through Canada. Some get stopped at the border, but you don’t know what gets through.”

On the flight to Buffalo, he had sat next to a doctor, a reservist being called up to Saudi Arabia. They talked of terrorists and mid-flight bombs, and the doctor was unperturbed. “He said, ‘It’d be instant death, you wouldn’t know it, and my wife would be rich.’ ” Downey shook his head, marveling at such sang-froid.

O’HARE INTERNATIONAL

Lee Larsen knew it was really serious when they started carting off the potted plants. From the counter of Faber’s airport drugstore, next to the turntable of single-dose, 69-cent Bayer and Nuprin, which look to be selling well these days, she could watch as “they took all the garbage cans away, the newspaper vending machines, the majority of the plants, and they put grates over the rest,” so there would be no place to hide a bomb.

Next door, the 24-hour game arcade was told to close down at 9 p.m., to the griping of the lobster-shift airport workers who like to rack up points on High Speed and Battle Shark in the small hours. The yellow note in the window apologizes for it, and adds, “We pray our men and women come home safe & soon--ASAP.”

The security people also insisted that Larsen put away the batteries and cigarette lighters that Faber’s sells. They locked up washrooms and elevators.

“A lot of our employees have approached me and said they’re afraid to be working here, afraid of terrorism,” Larsen said. “So you comfort them. But there’s no safe place. And the airport is not the greatest place to be.”

In six days of war, 10,000 combat flights have been dispatched across the Persian Gulf; in one day, 18,000 scheduled commercial airline flights take off across the United States.

Their domestic business, the major airlines say, is not down appreciably (in part, perhaps, because the demise of Eastern Airlines has shunted business to them).

But international travel has fallen to below half on some routes. TWA has cut its flight schedule by a third and is laying off 3,000 workers. American Airlines, among others, is allowing changes and refund vouchers on even the sternly worded no-changes, no-cancellation tickets, for people too panicked to fly.

“A large number” have taken them up on it, said an American spokesman.

UNITED FLIGHT 659, DALLAS TO DENVER

United Flight 659, Dallas to Denver: They’d made such a big deal out of it at the trade show, about the mess there’d be at the airport with all the new security, that Bill Dual, the president of a Bend, Ore., kite and windsock company, made a point of getting there three hours early.

He even packed up and checked the lights and wiring he normally carries aboard the plane with him, just so there wouldn’t be any hassle. So what happened? He was about 2 1/2 hours too early. He cooled his heels and watched security. He wasn’t impressed.

“It was kind of scary to sit and watch the haphazard system. . . . Somebody would beep off and there was nobody there to see them, and they’d continue walking. It seemed kind of loose, a lot of people doing it, but it seemed like they missed a lot.”

Like the woman with the purse. “For some reason she didn’t put her purse on the conveyor. She carried it through, she beeped, she put her purse down on the ground, she went through the second beeper, she didn’t set it off, she walked through, walked right around, picked up her purse and walked off. Her purse never went through anything.”

DALLAS-FT. WORTH AIRPORT

The guest book propped on a table in an interfaith chapel was, until Jan. 16, inscribed mostly with grateful prayers of the expected sort: “Thank God for a safe flight.” That night, though, the war began, and the world changed, and so did the prayers. That night, a woman named Janice, from Guadalajara, wrote, “Have mercy on all, oh Lord, and spare lives and grant us a speedy victory.” On Sunday, someone scribbled “Peace on Earth.” A man named James wrote, large and clear, “God bless all who seek peace.”

The tone inside the chapel--somber, restrained--has flowed out of its double doors and into the boarding areas. Dawn noticed it right away, when she came back from maternity leave to work at the yogurt shop on Thursday, the first morning of the war. People “don’t get impatient, even though they have to wait. You look out right now and you don’t see anybody smiling.” Instead, in chapel-hushed voices, they talk about the war. On the train that moves around the airport. In the cafes. In the bar down the way, people crowded in. Most did not even bother to pretend they were paying customers; they were just watching the television.

BURBANK AIRPORT

People kissed farewell in front of Walter Wilson, an airport security guard. A woman leaned and walked and leaned again to keep her mother in sight, far down the corridor, past the checkpoint where Wilson stood watch.

“Some of them are emotional, they want to see the plane take off.” But they don’t let them do that at the Burbank airport any more.

At the conveyor belt, three guards looked at the screen. A fourth was ordering a woman in a pumpkin-colored shirt to unpack something from her bag. She unwrapped it; a ceramic swan, the size of a navel orange, painted gold. The guard tapped it, put his ear to it, and handed it back to her.

Person by person, Wilson looked from ticket to face to ticket again. “When they get a little tight on me, I say, ‘You know we’re having a war, don’t you?’ ”

He stopped a young man with olive skin, black hair, glasses. The young man wore white jeans and a leather bomber jacket, carried no hand luggage. Wilson walked him to the metal detector, passed him through to another guard, who slapped the chest of the bomber jacket, then the back, then down the length of his white pants. The young man was allowed to walk on. Beyond, he turned, sour-faced, to throw back a kiss.

“Suspicion: I’d rather make a mistake and see you here again,” the security guard said, and then turned to the next in line.

“Sir? You got a ticket, sir?”