I AM SITTING in seat 20E on a United flight to San Francisco and I am very, very scared. We are preparing to take off. My palms are sweating, my heart is pounding, my breath is coming in short bursts.

Our stewardess, Tracy, introduces the flight-safety film, which on United has replaced the usual ho-hum safety lecture. The other passengers are reading, adjusting their seats, chatting. Do they care? Or am I the only one afraid I'm about to die?

"Please pay attention," says Tracy. "This information could save your life."

Dead silence. I stare intently at the screen, but then I always do. I'm a classic white-knuckle flyer, a person who dreads getting on an airplane. But I notice that on this flight, I'm not alone. I look around and see a planeload of grim faces staring in frozen intensity at the big screen, taking in every word about how to fasten your seatbelt. It occurs to me that maybe everyone else on United Flight 21Y is terrified too.

The captain tells us we can listen to the air-traffic control tower by tuning into one of the music channels. There aren't a lot of takers. In fact, most people seem to be avoiding looking out of the window.

The plane taxis down the runway. To calm myself, I use an exercise my hypnotist has taught me, in which I count backward from 10 to one during takeoff, trying to make my mind a complete blank. It doesn't work. This is where I start to hyperventilate. The plane is not going fast enough to take off. But then, how can it? How can a huge hunk of metal actually fly?

Ten . . . the Detroit crash pops into my mind. Did they remember the flaps? Nine . . . the Los Angeles midair collision over Cerritos. Eight . . . maintenance, they've cut back on maintenance since deregulation. Seven . . . wind shear. Six . . . the air-traffic controllers. Five . . . the Delta near-collision over the Atlantic. Four . . . the flight over the Pacific Ocean where the pilot turned off the engine by mistake. Three . . . the Air Florida crash over the Potomac. Two . . . the TWA flight's failed landing gear. One . . . the president's helicopter had a near-collision . . . . My God! Even the president isn't safe!

We're in the air at last. We've made it through takeoff. Once we are in the air and the seatbelt sign is off, Tracy tells us that there is no smoking in the lavatories. "The alarm will go off and it will be very embarrassing for you and you will be asked to deplane immediately."

Very funny. It takes a minute for the nervous titter of laughter to subside. This is not Tracy's last effort at humor, nor the pilot's for that matter. They know we're scared. When there is the tiniest turbulence and the captain advises us that we should fasten our seatbelts because the "skies are not so friendly" there is an instant, uniform click.

We're getting ready to land. I wonder if we're really at San Francisco. Once that question would have seemed absurd, but not any more, apparently. Tracy reassures us: "The captain has turned on the no-smoking sign . . . indicating he has found the airport." When the plane finally lands, the passengers applaud.

United Flight 21Y was one of three flights I took this month as part of a book-promotion tour. I should say only three, because I canceled the bulk of my tour after the Detroit crash and the series of near-collisions over the summer. Quite simply, I was afraid to fly. I toured the East Coast by train and did radio interviews over the phone for some of the cities I was supposed to visit. When people hear why I cancelled, many are sympathetic and confide in me that they, too, are afraid to fly.

People used to tell me I was crazy to be so scared. They laughed at me. Twelve years ago when I had to promote my first book, I took a fearful flyers' course. Then I went to a hypnotist. He's the one who taught me to count backwards from 10. As you have seen, that didn't work. I was still terrified. I went to a psychiatrist. She said that often when people reach midlife they begin to fear flying because they realize they have so much to lose.

Today, nobody thinks I'm nuts to be afraid of flying. I'm not the butt of other people's jokes. My formerly unafraid friends flock to me now as if I were the guru of fearful flyers. And do you know why? Because they know we white-knuckle flyers had it right all along. It's not safe to fly. Don't tell me to go see a hypnotist today. I don't want anybody hypnotizing me into believing that it's safe when it's not. It would be like hypnotizing a soldier not to be afraid of dying before he went into combat.

Even Drew Lewis, former secretary of transportation and now president of Union Pacific Corp., has some concerns about the current situation:

"It's a World War II kind of system," he says of the air-traffic control mess. The system will have 50 percent more planes in 1992, he says, but the same computer system. "The bottom line," says Lewis, a former pilot, "is I am concerned about the equipment, especially in bad weather when the planes are stacked up. And I think the real problem is the pressure on the control system, the hours being worked by people."

Great. That's reassuring.

Don't tell me about the statistics. I know they show that flying is safer than almost anything, that America has the safest air system in the world, that fewer people die in airplanes than in bathtubs.

But let's look at some facts:

The air-traffic control system is strained. The National Transportation Safety Board issued a report in May saying that the system was understaffed and overworked. It called for a cut in traffic during the peak summer season. The FAA rejected the call by air-traffic safety officials to limit traffic in peak hours. There are 9,695 fully experienced air-traffic controllers now as compared to 13,348 when President Reagan fired them in l981. Meanwhile, according to the FAA, there has been a 26 percent increase in air traffic over the last three years.

The skies are too crowded. There were 512 near-collisions in the first six months of 1987 compared to 390 in the first six months of 1986. The danger of mid-air crashes with small planes is serious in part because only 55 percent of all private aircraft have transponders, the devices that automatically report altitude to the air-traffic controller, according to an FAA official.

The system needs help. The FAA did not rebuild it's air-traffic control system after the firings and now there is a 40 percent attrition rate. This year there will be 2,600 fully trained controllers ready to retire, according to a congressional source. Moreover, the FAA has only 5,769 computer technicians working today, rather than the 9,000 technicians its critics believe are necessary. Their average age is 50. Many of them will soon be eligible to retire. It takes two to five years to train technicians. (The FAA says that because of advanced technology, it doesn't need as many technicians as it used to.) Finally, there are 1,804 FAA inspectors today -- short of the 1,975 recommended by the General Accounting Office.

Pilot training is down. Pilots today have less experience than they did four years ago. In 1983 the average hours of experience was 2,300. Today it is 1,400. On Friday the FAA criticized Delta Air Lines for "instances of a breakdown in communications, a lack of crew coordination and lapses of discipline in Delta's cockpits."

Then there is deregulation. The purpose of deregulation was to make air travel accessible to more Americans by increasing competition and lowering costs. It's called capitalism. Competition has certainly increased, but not necessarily in ways that benefit the public.

What's happened is in many ways the opposite of what was proposed. Prices to many places -- for instance, Washington to New York or Boston -- have soared. (Take Piedmont to Raleigh-Durham and the lowest tourist fare is $128 round trip, they tell you. But if there are only a few seats left or you want to go Monday and come back Tuesday without spending Saturday night, the cost is $350.) Many flights to less profitable markets have been canceled altogether.

Air transportation has become a cutthroat business. The eight largest airlines control nearly 95 percent of the market and many have swallowed up their smaller competitors. More people are flying than ever before, but there are new problems, too. Many of these large airlines control most of the business in their hubs, or headquarters around the country, leaving the passengers totally dependent upon them. All of this leads to delays, overscheduling, loss of baggage, even terrible food. This doesn't affect safety directly, but it adds to the public's uneasiness about flying.

But never mind inconvenience. Let's talk about death. With deregulation, the airlines have had to cut costs. Across the board. And inevitably, that means maintenance. A report prepared by the Flight Safety Foundation says deregulation has meant "relaxed maintenance programs and adherence to minimum equipment lists" and claims a "reduction in financial ability of air carriers to undertake safety initiatives in excess of FAA minimum requirements."

I only hope the airlines economize on cosmetics like comfort and food rather than onmaintenance. Frankly I'd rather be cramped and starved than dead.

So whose fault is it? Who's to blame here? There's a crisis and every air traveller knows it. We need accountability, and it's time to put some heads on the block.

My own list of culprits includes, in this order: President Reagan, Transportation Secretary Elizabeth Dole, former FAA head Donald Engen, the Congress that enacted economic deregulation of the airline industry and the airline industry itself.

President Reagan fired the air-traffic controllers and then never took resonsibility for beefing up the system subsequently. In fact, President Reagan acts as though he is totally unaware and unconcerned about the whole mess. But he is the president. He is the boss of the secretary of transportation and the FAA administrator. He's not uninvolved.

Nobody likes to see a near-collision like the one in which President Reagan's helicopter was almost hit by a small plane near Santa Barbara. But if there was anything that would force him to focus on the air-safety issue, I thought, it would be that. A vivid personal experience. But no, wrong. Nothing. Not even a word. Maybe the president could be inconvenienced by delays or lost baggage! But that's unlikely traveling on Air Force One.

What about Liddy Dole, the First Lady of Air Safety? Here is a woman who has been secretary of transportation since l983 (and will step down Oct. 1 to campaign for her husband, Republican Sen. Robert Dole). She has presided over the latest spate of problems with air-traffic controllers, pilots, transponders, engineers, delays, near-collisions and mergers of large airline companies. She is in charge of the FAA. If President Reagan wasn't going to provide leadership, why didn't she? You would think that because her husband is running for the presidency that she would have seen air safety as an important issue. But she dropped the ball. It was Liddy Dole who refused to abide by the National Transportation Safety Board's warning to cut air traffic during peak summer hours. Instead of taking the heat herself, she trotted out FAA chief Donald Engen to take it. His successor, Allan McArtor, has been there too short a time to tell whether he will do anything or not. He has at least admitted that the system needs work.

Which brings us to the airlines themselves. Greed is the operative word here. There's nothing wrong with making money, and left to their own devices that's what most companies do. Some spend more on safety than others. But in today's hypercompetitive market nobody has the luxury to worry about the public good. It's probably too much to expect them to regulate themselves. Somebody has to do it for them or more people are going to die.

So what should we do about this mess? Let's just say, for the sake of argument, that President Reagan decided to name a white-knuckle flyer like me as secretary of transportation. Would I be able to do anything? You bet!

For starters:

I would make it against the law for any private plane to take off without an altitude-encoding transponder. Anybody who can afford a private plane can afford the money it costs, and if they can't, that's tough bananas. Private planes, and their powerful lobby, are a big part of the air-safety problem.

I would hire more traffic controllers and make sure they are properly trained. I would also insist that the ones now in place have two days off a week, get sick leave and not have to work terrible overtime hours.

I would step up training of traffic controllers, computer engineers and pilots and make the training programs for all airlines standardized, including the best and most expensive training. I would also insist on a large computer system and cut the bureaucracy that stands in the way of building one.

I would crack down on the airlines and insist that they do more responsible scheduling, particularly in peak seasons and hours, when the traffic load is so heavy. At the same time, I would regulate airport capacity, insisting that small airports not be allowed to take on so much traffic.

And finally, I would speak out and make the public even more aware of the dangers and the facts about flying. Whether this is the safest airspace in the world or not, the public perception today is that flying is geting more dangerous. And that perception didn't come from nowhere.

A friend of mine was flying recently from Washington to Boston at night when suddenly there was a horrible lurch and the plane took a dive. When the pilot finally righted the plane, there was no announcement and the stricken passengers flew the rest of the way in frozen silence. After the plane landed, my friend, a formerly confident flyer who travels a lot in her work, asked the pilot what happened. "We almost hit another plane," he said. "They don't know what the hell is up there tonight."

Well, I'm sorry, but that's not good enough. Like millions of flyers, I'm outraged, disgusted and terrified -- and I want something to be done about it. I'm tired of excuses and gobbledegook and lies. There are lives at stake here -- namely mine -- and I don't want to die.

I am reminded of comedian Shelly Berman's gag: "Flying is the safest way to fly."

Not any more.

Sally Quinn, the author of "Regrets Only," is working on a sequel.