Every airplane crash that is classified as "survivable" has a lesson for future passengers as well as the airline industry.

In the fatal crash at Los Angeles Airport last month, at least 17 people who survived the initial impact failed to escape the cabin in time.The causes must remain surmises, but a prime lesson, tragically, is that while passengers half-listen to safety briefings or, at home, gasp at news photos of leaping flames and twisted fuselages, they do not always internalize the connection between the two.

This denial of real, if remote, possibilities, is buttressed by the mixed message in the script airlines write for flight attendants, or display on videotape.

An obvious example is the attendants' standard opening, along these lines, "While we are here to assure a comfortable and enjoyable flight for you, we do have concerns for your safety, too": safety, in other words, is subordinate to providing food, drink, blankets, pillows and magazines.

Yet from the standpoint of flight employees' training and their real duties, safety comes first, second and third.

As the airlines always point out, taking an automobile to the airport is, mile for mile, more dangerous than riding in a plane, but prudent car drivers take precautions - wearing a seat belt, cleaning the windshield, adjusting mirrors - while the same people get into a plane and presume someone else will take care of it. A message of passivity comes with being crammed in and encouraged to stay seated.

But the harsh truth is that in a survivable crash on takeoff or landing, when most crashes occur, survival time is measured in seconds: You must act purposefully, unbuckle, find an exit and get out before smoke or fire kills you.

Federal rules specify that passengers must be able to evacuate an aircraft in 90 seconds. The 67 people on the 747 who survived the Los Angeles crash and fire got out in two minutes.

People do not readily absorb how much personal initiative will be required for survival if they live through the impact.

This was shown in a 1989 study by the Transportation Safety Board of Canada. Terry F. Kelly, the superintendent of safety studies for the board, acknowledging that the method was not very scientific, said 517 Canadians were interviewed after they disembarked from passenger planes at two busy airports to learn what they remembered about their safety briefings.

Ninety percent of the people interviewed recalled seeing a safety briefing card, but only 29 percent said they had read or looked at it.

The more frequently passengers had traveled in the previous year, the less likely they were to have looked at the card. However, two-thirds of the passengers felt confident they could, without help, open the exits in the event of an evacuation.

Of these people, 56 percent said they had learned how to open the exits by reading the instructions on the doors, but Kelly reported that since it was unlikely that 179 people had had a chance to inspect the doors on the flights they just left, they were probably basing their assumptions on an earlier flight.

Perhaps the most dismaying statistic was that 91 percent of those interviewed felt that the amount of safety information provided on the plane was "just about right."

In the investigation of the Feb. 1 crash of the USAir 737 into a commuter plane at the Los Angeles airport, three of the four passengers who were seated in Row 10, next to the exit on the wing, testified that they had heard and understood the special briefing that since October must be given to passengers near exits.

The fourth passenger, seated directly next to the exit, who has not talked to the investigators, did not move to open the door, which was released by a passenger from another row.

The new Federal Aviation Administraton exit-row rule sharply restricts who may be assigned to these seats: Children, the blind, the disabled, the deaf and others, including people who do not speak English, may not sit there.

The new safety-briefing cards reiterate the exit-row rules, and are supposed to reinforce the message that if a passenger does not want to carry out the required duties in an emergency, he or she should ask for another seat. Some airlines have a separate briefing card for the exit row; some present it as part of the regular printed briefing.

At USAir, according to Nancy E. Vaughan, a spokeswoman, flight attendants are expected to go to the exit row and "visually assess" the people there. This often involves giving the briefing orally to the row.

But the message is not always clear; as I boarded a Continental flight recently, the last words of the exit-row briefing were being broadcast and the message was not repeated. More important, it is not made clear that the emergency exit door, which detaches, is heavy.

I have with difficulty removed a 45-pound door. Some doors weigh 65 or 85 pounds, and people in the exit rows have no way of knowing this unless they ask.

The Los Angeles crash was still under investigation by the National Transportation Safety Board when a symposium of airline safety experts convened the next week in Costa Mesa, Calif., to hear the Canadian report and others on cabin safety.

Jim Burnett of the U.S. safety board, who was in charge of the investigating team at Los Angeles, spoke on the lessons he saw in that crash and earlier ones. He said regulatory inaction, or inadequate action, resulted in delays in evacuation and needless deaths in the 747. He did not remember a disaster in which so many people survived the impact but could not escape.

The first issue Burnett cited was the lack of space in the row next to the over-wing emergency exits. Investigators were told by witnesses that there was a scuffle between two men trying to get out of the same exit at the same time.

"We do not know what kind of a delay this caused," Burnett said, "but people who did not survive were headed" there.

Burnett said that the Civil Aviation Authority in Britain, after a fatal crash in Manchester, England, conducted videotaped tests in which people competed for money to be among the first to get out of a fuselage with exits randomly blocked.

Various arrangements were tested and the British then required a bigger space in the exit row. On the basis of the British research, Burnett said, the FAA called in a working group, did not get a consensus, conducted research and began drafting a regulation on the row width.

"Now the issue is at the Office of Management and Budget," he said.

"The problem with cost-benefit analysis is that we have few events. You have to wait until you have a human cost. It is high time that somebody took responsibility for denying it or speeding it through."

Listing the lessons of other recent crashes, he cited delays in requiring that older planes be refurnished with fire-retardant materials; failure to teach fire companies in all airport neighborhoods how to open aircraft doors; lack of a rule requiring that children under 40 pounds and 40 inches be buckled into safety seats for takeoff and landing; lack of a rule requiring life jackets on all planes, not just flotation seats, and lack of a requirement that flight attendants undergo "wet drills."

Besides absorbing the briefing card, what should a passenger do to be ready in an emergency? Ken Burton heads a survival-teaching company in Panama City, Fla., called Stark.

His most frequent task is training corporation executives for trips in corporate planes. Burton has a rather drill-sergeant manner.

"Memorize that furniture!" he barks.

"Get so you can envision the whole plane inside and the number of seat backs to each exit.."

The closest exit may be blocked, or, as in the Los Angeles crash, opening it may disclose fire outside and you may have to reverse direction. Be prepared to count seat backs the other way, going on past your own seat. It will be dark and smoky, and you should bend to keep your head low, but not so low that you are trampled.

Nylon stockings melt at high heat, and high-heeled shoes are a hazard when moving fast. Hair spray is also flammable.

People with a fatalistic approach tend to ignore such information, but real issues of survival have a way of banishing the notion of "if it's time, it's time."