In the days before flying to visit her newborn grandson in Southern California, Sandra Birnbach's hands started sweating. Her stomach churned and her head throbbed. A claustrophobic, she dreaded even the thought of boarding an airplane.

And that was just the beginning. She agonized over the wait at security and, worse, a potential delay stuck sitting in the plane waiting to take off. Even though her therapist drove her to Reagan National Airport for the trip in November, Birnbach cried during the entire ride to the terminal. On board, she warned a flight attendant about her condition. She didn't want to alarm the crew or other passengers if she had a panic attack.

"I pray a lot, 'May the plane take off on time and not sit on the runway for two or three hours,' " said Birnbach, a suburban financial planner. "There is this catastrophic feeling when I get on a plane. It's hard to explain, but it makes you feel like there is some catastrophe that is going to happen to you if you can't get off the plane."

For many people, flying is often an irritating experience. But mental health experts say few periods have been so difficult for those who suffer from severe flying anxieties and phobias. Tight security, crowding and delays have worsened their conditions.

"It's a nightmare time for people who are anxious," said Jerilyn Ross, a psychotherapist in Washington who works with such clients.

At home, the anxious agonize about how to pack their bags to navigate security requirements limiting the amount of gels and liquids in carry-on luggage. At the airport, they are warned to watch for unattended luggage and that the aviation system is under high alert. Security lines, which sometimes take an hour to navigate, offer plenty of time to sweat.

Once aboard, claustrophobics often face another threat: Planes increasingly are packed with passengers because airlines fly fewer planes to boost capacity.

Also, recent news of air fatalities has left some travelers unsettled. A regional jet crashed in Kentucky in August, killing 49 people. In October, two jets collided in Brazil, and later television screens were filled with images reminiscent of the Sept. 11, 2001, terrorist attacks after a small plane, flown by a New York Yankees pitcher and his flight instructor, slammed into a Manhattan high-rise. Most recently, an airliner with 102 people aboard disappeared over Indonesia.

There are no statistics on how many people suffer from severe flying anxieties or phobias. But mental health experts say their patients exhibit the most extreme symptoms felt by millions of other air travelers.

"You can't not have some anxiety when you hear all of those cues around you telling you of the dangers," said Ross, director of the Ross Center for Anxiety & Related Disorders.

The 9/11 terrorist attacks were rough on anxious fliers. But many didn't seek therapy because they were comfortable discussing their fears with friends and colleagues. At the time, everyone seemed to understand why flying was scary.

But in recent years, more people have sought help as air travel has picked up and as many travelers cannot find ways to avoid flying for business or pleasure, therapists said.

Many fearful fliers aren't afraid of a crash, experts said; rather, they suffer from claustrophobia, a fear of being in tight spaces. Some are terrified of having a panic attack and embarrassing themselves, or of even getting tackled by security-minded passengers, therapists said.

"A lot of people are afraid that when that door shuts, they are going to do something crazy," said Jean Ratner, a suburban therapist who works with anxious fliers.

"The gels thing really raised the whole fear of terrorism all over again. It was a mini-9/11."

To help travelers, whose phobias also often affect them in elevators, crowded commuter trains or other passenger compartments, Ratner creates a detailed treatment plan. Each patient gets a personalized audio tape to help deal with stress. Most are taught to think of soothing memories or places when they feel anxiety approaching.

Like many claustrophobics, insurance salesman Robin Wexler, 61, waits to be the last person to board a plane.

His wife, Elaine, felt it was "a job" to calm him during flights and made him seek therapy from Ratner. "He wasn't willing to travel on his own," she said. "I told him I wouldn't always be able to fly with him."

Traveling with him "was tense," said his daughter Emily Wexler, 28. "We are happy he is seeing somebody."

"In my business and personal life, I am always the one who determines a course of action," said Robin Wexler, 61, who negotiated Reagan National Airport with his family for a recent vacation to Mexico. "On an airplane, I am at their mercy.

"I get antsy, if we are not moving and just sitting on the runway for a prolonged period of time, I get really antsy. I am having a full-blown anxiety attack over it. It used to be painless, and now it is anything but painless."

Sitting inside a plane stuck on the taxiway is particularly unnerving because he feels trapped, he said. To calm his nerves, he imagines something far removed from the cramped, stuffy cabin: a sunny golf course, or playing with his 2-year-old grandson.

So far, it has worked.