Escape: Because Accidents Happen: Plane Crash

PBS Airdate: February 17, 1999
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ANNOUNCER: Tonight on NOVA. From the early days of flight, they pushed themselves to the limit to come up with better ways to escape, "Because Accidents Happen." Would you believe passengers walked away from this crash? When disaster strikes, can you get out alive? Fasten your seatbelts for "Plane Crash."

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NARRATOR: An aircraft falls out of the sky. For the military pilot, there is one last chance of escape. For airline passengers, the only hope is to survive a crash landing.

JAN BROWN-LOHR: When we slammed into the earth, I could never have believed that we could have hit that hard. It was like, your instantaneous thought was, 'I can't believe that the bones of my body are still connected.'

NARRATOR: There will always be aircraft accidents. The problem is how to make them survivable. Airline tragedies have forced engineers to confront the question of how to design planes to enable crash victims to escape with their lives. The First World War introduced young aviators to the real dangers of aerial combat. If their aircraft were hit, they had no means of escape. On the Western front, the crews of observation balloons were in an even worse position. Patrolling behind enemy lines, they were sitting targets.

PETER HEARN: If you can imagine this, in a little cage beneath a balloon full of hydrogen with nasty people coming along in airplanes firing tracer bullets at you. You needed an escape system. It was just a case of wearing a harness attached to a parachute that was in a container on the edge of the cage, and all they did was hop over the edge. And their falling weight would pull the canopy out of its container.

NARRATOR: Although the lives of hundreds of balloonists were saved, parachutes were thought to be unsuitable for airplane pilots.

PETER HEARN: Now, what they couldn't do was apply this same technology the airplane, because the airplane isn't standing still like a balloon. The airplane, at best, is flying at a certain forward speed. At worst, it's going to be tumbling. It's going to be burning. No easy way to get out of that with a chute that is already attached to the airplane.

NARRATOR: Most pilots would have rather taken their chances with a parachute, even if they risked tangling it in a spinning aircraft. But the generals feared pilots might be tempted to abandon their planes at the first whiff of danger. Towards the end of the war, a German pilot was shot down, but managed to escape using a parachute attached to a can outside his aircraft. The war was over by the time the Allies decided to install parachutes. The idea of parachute escape was first conceived by Leonardo da Vinci. Several Renaissance thinkers imagined it might save people from burning buildings. But it would remain a paper idea for three centuries. It works by the simple principle of counter-acting the downward force of gravity with the upward force of air resistance from the canopy. The first public demonstration was in Paris in 1797, when a showman jettisoned his balloon and fell to earth on a parachute. Parachutes have always been associated with daredevil stunts. In California, the public enjoyed spectacular air shows, which often ended with jumps. But the parachute was still folded in a canister fixed to the plane. One of the best known jumpers was a showman with the nickname "Sky High" Irvin. He made his first jump from a balloon when he was 14, and had appeared in Hollywood movies. By 23, he was one of the most experienced parachutists in America, and would be the guinea pig for a dangerous experimental jump. In April, 1919, Irvin was selected by the Air Force to do a jump with the parachute strapped to his back instead of to the plane. The folded chute would be ripped out of the canvas pack with a cord. Many feared he might black out during the dive and not be able to pull the rip cord. But the parachute's designer, Floyd Smith, who flew the plane, was confident.

PETER HEARN: Now, both Leslie Irvin and Floyd Smith, they had done high dives, they had done trapeze work, Floyd Smith as a profession for the circuses, Leslie Irvin just for the hell of it. Now, they knew that when they did these high dives, rather than losing consciousness, they became pretty damn sharp. But was he going to be able to pull that rip cord? Or was it true, as all the scientists and doctors said, that he would lose consciousness? So, there was a great curiosity around McCook Field. There was an ambulance waiting there, which he didn't much like the look of.

NARRATOR: This would be the world's first free-fall jump. Would the acceleration be too much to bear? Would he lose all sense of time, and delay pulling the rip cord too long? Would the weight of his falling body be enough to pull open the chute?

PETER HEARN: He pulls the rip cord, parachute opened, no problem. Except, he did break his leg when he landed, but that was nothing to do with the parachute.

NARRATOR: Irvin capitalized on the success of his jump and set up the Irvin Parachute Company. It soon became the largest parachute manufacturer in the world. The military realized that parachutes were so reliable, they could be used not just for saving air crews, but for deploying troops. And so, the paratrooper was born. They would become the cavalry of the air. Meanwhile, during the 30s, airline travel had become popular with the public. It was far more dangerous than traveling by land or sea, yet if there was an emergency, passengers had no effective means of escape.

FILM ARCHIVE PILOT: One control released as a harness and padding from the seat, enabling the passengers . . .

NARRATOR: Aircraft designers began thinking of ingenious ways of getting passengers out of planes, like the trapdoor release, and the swing seat egress. One parachute company even made a promotional film to try to persuade airlines to provide parachutes for everyone.

PILOT #1 IN FILM: It's no use, Glass, we'll never make it. Take your chute and come back and help Mary with the passengers.

NARRATOR: In the days of propeller-powered aircraft, engine failure often caused accidents.

PILOT #2 IN FILM: Sorry, folks, we have a little trouble. So, we'll go down by parachute. Now, don't worry. There's nothing to it.

FLIGHT ATTENDANT: They're all ready.

PILOT #2 IN FILM: All right, sir, you're first. Just step right out. The chute will open automatically.

FILM NARRATOR: Alive and uninjured. But how different it might have been.

NARRATOR: Mass parachute evacuation for airline passengers would remain a fantasy.

PILOT #2 IN FILM: Yeah, Jim Carson, the pilot.

NARRATOR: In reality, people not trained in parachute jumping risked serious injury, so the airlines never took up the idea. In military planes, the parachute became the pilot's main hope of survival. During the Second World War, it saved thousands of airmen's lives. But as aircraft became faster, bailing out became more difficult. Ground tests on a Spitfire showed the effects of wind blast, when a pilot tried to climb out of the cockpit.

FARNBOROUGH ARCHIVE: At higher speeds, it may even be impossible for him to get out of his cockpit unassisted.

NARRATOR: Even if he could force himself out at such high speeds, he would risk smashing into the tail. A new method of escape was needed. Unknown to the Allies, in Germany, the Luftwaffe was already working on the problem. Their new prototype jet could travel at over 500 miles per hour. So, bailing out with a conventional parachute was impossible. German scientists began trials to see how air crews might cope with sudden acceleration forces. During an ejection, they would need to survive extreme air blasts. Much of this work was carried out at a top secret research airfield at Rechlin, in what would become East Germany. It was badly bombed in the final days of the war, and little remains today. Returning for the first time in over 50 years, these men were all involved in high speed escape. Theo Knacke is an engineer who left Germany after the war to work for the Air Force and NASA. One of his first tasks was to design a parachute which would not be ripped apart at high speeds. His ingenious chute was made of silk ribbons. They allowed the sudden blast of air to be released between the gaps. After a few seconds, the weight of the falling pilot forced the ribbons to cling together, supporting his descent like a normal parachute.

THEODORE KNACKE: What you see here are called ribbon parachutes. The principle of this, these should open much slower than the regular parachute. They are more stable. They have a much lower opening shock, and the opening shock allows us to use the chute in excess of 400 to 500 knots.

NARRATOR: But getting the pilot safely out of the cockpit was still a problem. The most important development to come out of Rechlin was the ejection seat. The seats were fired with compressed air using the same principle as an air gun. Controlling the right amount of air was difficult. If too much was used, the pilot's spine would be crushed. One of the first to survive an ejection in battle was the Luftwaffe pilot, Otto Fries.

OTTO FRIES: I was at 7,000 meters when I was shot down by a Mosquito. The left-hand engine was on fire. I couldn't see a thing. I had blood in my eyes. But I instinctively grabbed the stick and braced myself and pulled the plane out of its dive. And then, I knew - My brain was hardly working at all - But I knew that I had to eject. But I just couldn't remember where the release lever was. And then, I felt my pocket torch, hunted around with it, and eventually found the lever. Then, I lifted the lever, forgot to lean my head back, and ejected. And of course, I tore my neck muscles. I was turning head over heels, and I was still in the seat. First, I had to get rid of it, and it fell away. And then, I waited a bit. You have a certain feeling for height, even at night when you can't see anything. And then, when I could feel the clouds, the moisture, I thought, 'Well, this must be about 1,200 meters,' so I pulled the rip cord. The chute opened, and came down onto a cattle pasture. And just in front of me, not more than a meter in front of me, there was a cow-pat. And when I got myself out of the chute, I thought, 'You lucky bastard.' (laughs)

NARRATOR: The Allies never built an ejection seat until after the war, when a small aircraft company in England grew to become the world's largest manufacturer. The company, Martin Baker, was formed by an engineer named James Martin and a test pilot, Captain Val Baker. Shortly after it was formed, Baker was killed flying one of Martin's prototypes. So, the company stopped designing planes and began work on ejection seats. The small family firm grew under the watchful eye of James Martin, who had a mission: to save pilots' lives.

JAMES W. MARTIN: My father was a skilled, hands-on engineer. I mean, he was capable of operating any of the machinery in the factory. He was as good a draftsman as any of the others, and he had the capability to operate any piece of equipment in the place, and probably a lot better than some of the people he employed.

NARRATOR: In the 1940s and early 50s, Martin Baker carried out some pioneering research on how to eject a pilot safely. The pull-down blind protected his face from air blast, and ensured his elbows were tucked close to his body. By using small explosive cartridges rather than compressed air, a much smaller shock was inflicted on the body. The spine was only compressed briefly, reducing the risk of permanent damage. This was a major improvement on the early German seats. After several trial runs on dummies, they prepared for the first live ejection from an aircraft. The guinea pig was to be a Martin Baker employee, Bernard Lynch.

BERNARD LYNCH IN FILM: What about blast and high speeds?

JAMES MARTIN IN FILM: Well, in Germany, people have actually withstood air blasts on the face at over 500 miles an hour, for very short periods. All the same, the aircraft speed should be as low as possible before shooting yourself out.

JAMES W. MARTIN: I think in those days, there fortunately just happened to be a lot of very brave people around, particularly that chap called Bernard Lynch, who was a fitter. And he was a volunteer, although I have a feeling he was probably volunteered. And he, I know, had enormous respect for my father and didn't believe that he was going to be asked to do anything which would kill him, although possibly it might hurt.

ARCHIVE FILM NARRATOR: Flying steadily at 300 miles an hour, Lynch gets ready to fling himself into space. First, he jettisons the hood. Then, feet clear of controls, he holds his breath, pulls his elbows in, and yanks down the blind. As he flies clear, seat and all, a stabilizing drogue opens to prevent him from turning over and over in the air. Then, out comes the seat parachute. Now, his next step is to free himself from the seat. In his own good time, slowly and calmly, Lynch does it. Watch just below the white canopy, and you will see Lynch's own parachute open as he falls clear.

NARRATOR: Initially, pilots were wary of these explosive seats. They did not like the idea of being human cannon balls. But as more and more lives were saved by ejection seats, they were soon adopted by Air Forces throughout the world. The unresolved question was just how much punishment the human body could take.

ARCHIVE FILM NARRATOR: Spotlighted for the first time, Air Force Colonel John Paul Stapp, a science pioneer in the little known field of aviation research . . .

NARRATOR: In the 1950s, a US Air Force Doctor, Colonel John Paul Stapp, volunteered to put his own body on the line. His experiments on himself would measure the maximum forces a human being could withstand in an aircraft ejection or a plane crash.

ARCHIVE FILM NARRATOR: From the outside, watch break-neck stop. Shaking off the effects of the rapid deceleration . . .

COL. JOHN PAUL STAPP, M.D.: This was no stunt. Everybody thinks it is, but it wasn't. The object was keeping people alive. When I first went, and when I was doing some serious thinking about using myself as the subject, I bore in mind that that is exactly what we were going to do, is save lives.

NARRATOR: There were some spectacular failures. Luckily, most of them were on dummies. Later, they used anesthetized chimpanzees to measure the effects of G-forces. But chimps and dummies don't talk. Stapp wanted subjects who could describe the experience. And that was a problem, because he was usually the subject as well as the scientist. So, he put in a request for a medical assistant.

COL. JOHN PAUL STAPP, M.D.: I went to my boss and said, "Look, I need somebody else here to observe. We can't do it all as subjective reports. Can you get me an assistant? And besides, I might not be able to remember everything that happened when I get enough Gs." He said, "You mean you're risking my promotion to Brigadier? You're grounded."

NARRATOR: Stapp was forced to use chimpanzees until eventually his boss was promoted. Only then was he able to restore human test runs.

COL. JOHN PAUL STAPP, M.D.: In all, we did 73 experiments with humans before we finally collected the information that we wanted. And for some reason, I was the only one that got two broken wrists and cracked ribs.

ARCHIVE FILM NARRATOR: Water brakes check the sled's speed in an instant. End of the line, and the Colonel, cheating death again, says he's fine.

NARRATOR: Stapp's most dangerous experiment was on a rocket-powered sled called Sonic Wind. It would simulate ejection from a plane at supersonic speed.

COL. JOHN PAUL STAPP, M.D.: This last human run took place on 10 December of 1954. They said, "Major, would you like some coffee and doughnuts?" And I said, "No, it makes a messy autopsy." That was to get them focused and serious, because you could have an autopsy. I had rehearsed sitting there and sweating out for five times. So, all I could think of was, 'Well, let's get this over with.' The sled hit me 19 Gs in 0.07 seconds, and that's like being shot out of a cannon. Now, as I went through the water brakes, my vision turned salmon-color from pressure going into the eyes, and when I couldn't see anything, I said, 'Oh boy, now I've really got it, and a white cane, seeing-eye dog, and all that.' And I looked up, and gradually, the orange gave way to blue. And they just hauled me over to the hospital. By the time we got there, I was getting my survival euphoria. All that could go through my mind was, 'Oh boy, I've paid the dues this time. They're going to treat me differently after this.' They did, but not the way I thought. (laughs)

NARRATOR: Stapp had become the fastest man on earth, and proved the human frame was much tougher than anyone thought. At the end of the 50s, he was asked to tackle a new problem. The US Air Force was testing experimental rocket planes that could travel many times the speed of sound, and fly to the edge of space. These were dangerous missions, and the Air Force wanted to be sure their pilots could survive bailing out. Preliminary tests on dummies showed that free-falling from such extreme altitudes would throw a pilot into a disastrous spin. So, they developed a small drogue chute to stabilize the descent. Now, Stapp wanted to know if a human being could survive the experience. He needed a volunteer as bold as himself who was prepared to take the dummy's place. Stapp decided Joe Kittinger was the right man for the job. He was an experienced skydiver and test pilot. But no one had parachuted from altitudes where the air was so thin it was impossible to breathe, and the pressure so low that only a special suit would stop his body from exploding. Kittinger would make his jump over the White Sands Missile Range in the New Mexico desert. The launch vehicle for the mission would be a helium balloon.

JOE KITTINGER: And we finally came here in November of 1959, and we were ready to go for the first flight. It was very cool out here in the desert, and I actually lay down on the desert and breathed oxygen for two hours. And you have to do this because you want to get rid of the nitrogen out of the body, so that you don't get the bends as you go aloft. And finally, we had gone through the checklist and everything, and I stood up and I walked up the steps, and I turned around, and I had all my equipment on. And I got in the gondola and said, "Well, we're ready to go. Everything's done, and now we're going to see what happens."

NARRATOR: The balloon rose steadily at 1,200 feet per minute. After an hour, it was ascending through the upper reaches of the atmosphere.

JOE KITTINGER: I get up to about 76,000 feet, and the command post said, "OK, it's time to go." When I started to pick myself up to step out the door, I found that I was wedged into the seat. Now, I had done this 100 times in the chamber, and I never had any trouble getting out of the seat. But one of my crew members had put new insulation devices in there to make it look neat. And when he did that, he decreased the area, and I was actually wedged in the seat and I couldn't get up. Now, here I am, I think I'm trapped in this doggone seat and I can't get up. And so, I'm really getting frantic because I want to get out of there, I want to get this test underway. And I jerked and I pushed and I pulled, and I finally stood up. But in doing so, I pulled a timer that I wasn't supposed to pull. And I jumped out of the door, and when I did, instead of falling for 16 seconds before anything happened, I fell two and a half seconds. And this little pilot chute came out and wrapped around my neck. And I knew it was a hell of a situation I was in, because here I was going to be free-falling like a dummy without any stabilization. So, I started free-falling. And I was a trained skydiver, and I got stable, and I was doing very good. And I was sitting there thinking, 'Well, gosh, you're going to be able to skydive all the way down to a safe altitude.' And all of a sudden, I started spinning kind of loosely to the left, and I stopped it, and I said, 'Ah-ha, that's very good, Kittinger.' And then, all of a sudden, I violently entered a horrible spin to the left. And I had on my left wrist, an altimeter and a stopwatch, and I had a great interest in this altimeter stopwatch, because if I was down at a lower altitude, I could pull the rip cord. But the centrifugal force was so great that I could not pull my arms in. And I was fighting to get my arms in, because I really wanted to look at that altimeter stopwatch, because if I had pulled the parachute above 30,000, the parachute would disintegrate and so would I. The G-force would be horrendous. So, you had to get below 30,000. So all of a sudden, I had this horrible spin, and I started to gray out ,and then I blacked out. And then, I came to at about 10,000 feet. My emergency parachute was open, and I came down and made a landing here in the desert on my emergency parachute. I was happy that I was alive, but I was disappointed that we hadn't conducted the experiment the way that we had planned to. And I was really concerned that we were not going to get permission to go ahead and do it again.

NARRATOR: Kittinger and Stapp persuaded the authorities to complete the real objective of the program: to jump from the edge of space at over 100,000 feet.

JOE KITTINGER: The difference is that you are really in space. At 76,000 feet, blood boils, so I always felt that if the pressure suit failed at 75,000 feet, I had a chance to live. I had a chance that I might survive. But when you go to 103,000 feet, there's no way you're going to survive. If anything happened to that pressure suit, you're dead.

NARRATOR: But something did happen. The glove on his right hand did not pressurize, so the blood began to pool, leaving his hand immobilized.

JOE KITTINGER: I opted not to tell my flight surgeon on the ground at the command post, because I knew that if I told him that my pressure suit glove wasn't working that he would tell me to abort the flight. And I was very—I did not want that to happen. I was a little concerned about what was going to happen, but I felt that I could overcome any obstacle that would arise. So, I jumped out. I free-fell for 16 seconds. I had perfect stabilization. At 90,000 feet, I reached a speed of 716 miles an hour, which was supersonic. But you see, I'm in a vacuum. I'm in a space vacuum. And I'm falling in this vacuum at extreme high rates of speed. But there is no way you can visually detect how fast you're going or where you are. And every second, I was falling and falling and falling, and I was getting back to a friendly environment. And this might not look like the Garden of Eden to you, but it sure looked like the Garden of Eden to me when I got on the ground, because I was elated.

NARRATOR: Joe Kittinger's record skydive still stands today. He had demonstrated that it was possible to escape from planes even at the very edge of space. But a new problem was emerging as military jets flew closer and closer to the ground to avoid enemy radar. Most fatal accidents happened when they were too low to guarantee safe ejection. So, the seats were fitted with rocket motors, which could propel the pilot up and away from danger, even when flying at ground level. As Stapp's research had shown, it was theoretically possible to escape as almost any speed or altitude. Today, at his old rocket sled track in New Mexico, engineers are about to test a new escape system. There will be no human volunteers on this run. It's a dummy in the seat. This prototype will be able to sense when a plane is about to crash. On-board computers will automatically trigger an ejection, and control its trajectory from the doomed aircraft. It could save a fighter pilot before he even realizes his life is in danger. To test the prototype, they will fire it down a 10-mile rocket sled track at 500 miles per hour.

BLAIR McDONALD: The seat knows exactly where it is. It knows where the ground is. It knows what the altitude is. So, the seat knows what to do to give the pilot the optimum possibility of a successful escape.

TEST ENGINEER: . . . minus ten, nine, eight . . . four, three, two, one, zero . . .

NARRATOR: High speed cameras show what happens at the moment the ejection seat rockets ignite. In a fraction of a second, the parachutes are deployed. The dummy floats safely back to earth. Whether pilots will entrust their lives to an ejection system that takes the decision to abandon the aircraft out of their hands remains to be seen. As the technology of escape becomes more sophisticated, the chance of surviving an accident in a military jet increases. In civil aviation, the problems have been different. The idea of passengers ejecting or parachuting out of a plane in mid-air was abandoned long ago. Research shifted to making crashes more survivable. In 1965, the Federal Aviation Administration staged its first crash test. This crash may look fatal, but many passengers would have survived.

RICHARD HALLION: I think one thing that the public at large fails to appreciate is how survivable an accident actually is. For most people, they have the vision that there is nothing left but some sort of a smoking hole and everybody is killed. But in point of fact, if you take a look at an aircraft accident where older aircraft were deliberately tested to the point of destruction, you realize that if you are able to keep the people alive in the cabin past the point where the fireball occurs outside the aircraft, and if you are able to protect them from the impact, that there is a high expectation that you will have a significant number of survivors from an accident.

NARRATOR: The FAA investigators realized that the key to survival was getting passengers out of the cabin before it filled with smoke. They used an old, crashed plane to conduct timed evacuation trials. Clamoring out of the over-wing exits was cumbersome and slow. Passengers had to help each other out. As airliners became bigger, they needed more emergency exits. These were often too high above the ground for passengers to jump to safety. So, some aircraft were fitted with evacuation slides.

S. HARRY ROBERTSON: OK, this is an example of one of the early evacuation systems to get people out of large aircraft, groups of people. And this design right here, it has to be manipulated, normally in the dark is there is an accident at night. It requires that this handle be pulled. As it is pulled, the chute will drop to the floor. At this time, you have to bend down and get help from somebody to find the handles. And then, these little clips tie into the rings at the floor and at the ceiling. OK, we have the lower ones . . .

NARRATOR: The early slides were made from canvas, and were difficult to deploy.

S. HARRY ROBERTSON: I've got one on this side . . .

NARRATOR: It would be hard to sort out this mess with a fire billowing outside.

S. HARRY ROBERTSON: So now, this seems to be it. I think we've got it right here. This goes right into the side on the top. We can throw this out, and let us slide down through the middle of it . . .

NARRATOR: Airlines began experimenting with escape slides in the 1950s. The early slides required the crew to exit first and hold out the chute for escaping passengers. Back then, when planes were smaller, they could be evacuated in two minutes. Today, even though aircraft are much larger, the requirement is 90 seconds. To speed up evacuation, all commercial airliners are fitted with self-inflating slides.

S. HARRY ROBERTSON: With a properly inflated slide, like this one is right here, about the only real problem you have is perhaps falling off the side if you get too many people on top of each other too quickly, or you will get some chafing or some friction burns on your rear end or on your elbows. But they are small problems compared to what could happen if you weren't out of the aircraft.

NARRATOR: In 1971, an accident in San Francisco revealed that under some conditions, evacuation slides could be dangerous. After an emergency landing, there was a small fire in the undercarriage.

S. HARRY ROBERTSON: The chutes were deployed, but the 20-mile-an-hour wind was enough to cause the slides to start to blow aft. And as people went to the doors, especially in the front of the aircraft, and they looked to the slides, they saw the slides weren't on the ground but they were blowing aft. So, they ran inside the fuselage back toward the tail of the aircraft. And as they did that, the tail of the aircraft settled down to the ground, the nose went up in the air, and finally, the front slides were gotten a hold of by people on the ground. But instead of coming out at a 45 degree angle like this, they were almost straight down. But the people inside the aircraft weren't aware of that at first. And a number of people ran and jumped down the slide only to essentially free-fall to the ground.

NARRATOR: A minor incident ended up injuring 27 people. Since that accident, evacuation slides have been redesigned to be much more rigid. These massive structures fully inflate in four and a half seconds. They are made of flame-retardant material to help protect them from pools of burning fuel. But it is not always possible to deploy evacuation slides. In 1989, a DC-10 bound for Chicago went dangerously out of control after an engine explosion.

JAN BROWN-LOHR: As I walked to the cockpit, I thought to myself, 'Well, we have an emergency.' But when I opened the door, it was - To this day, it still gives me chills. It just stopped me cold. I felt my blood run cold, because it was just the feel of what was in the air, that it was not an emergency, it was the worst crisis possible. The captain said, "We've lost all hydraulics. Secure the cabin and prepare the passengers."

NARRATOR: The plane was diverted to a small airfield in Sioux City. It hit the runway so fast, the fuselage started to break up.

JAN BROWN-LOHR: I just simply blacked out, and I was out for the duration. I could still hear all of the metal noises and noises you've never heard in your life, as we catapulted down the runway.

NARRATOR: The extreme impact had torn the aircraft apart, leaving the main cabin upside down. Amazingly, 184 people managed to escape. But 112 died, most of them from head injuries, as they hurled to the front of the plane, still strapped to their seats. Colonel Stapp's crash tests had proved that passengers could survive if they were properly restrained. This test, conducted two months before the Sioux City crash, demonstrated that the seat and seat belt attachments could fail on impact.

S. HARRY ROBERTSON: What used to happen—and in fact, it still does to some degree, but not like it used to - The seats would break loose from the floor, and the individuals would still be strapped in the seats, but they would all be wadded up in front against the front bulkhead. And there would be just a big pile of people, in their seatbelts and in their seats, stacked on top of each other. But they're like missiles, and they're piled on top, and there's no way you could get out. And so, if you could keep the seats from breaking loose and you could keep them restrained properly, there is a very good chance that you could let them live in more severe crashes.

NARRATOR: The latest planes are fitted with much stronger seats. But most aircraft still have seats like these. In the Sioux City crash, passengers who survived the initial impact faced another danger.

JAN BROWN-LOHR: I knew that I was in fire. It was a huge, round, red ball that I was suspended in. And then, just as quickly, the fire was gone. It seemed to be going forward to my - over my left shoulder. And within seconds, we stopped. And I was absolutely incredulous. I'm still thinking, in other words, 'I'm still alive.' And then, the job kicked in. It was like, 'If I'm alive, we've got to get out of here.' Everyone went out any opening they could find, and finally, I had to leave because this horrible, gray-black smoke was pouring towards me at the top of the cabin. And as flight attendants were taught, if the fire's too hot, the water's too deep, or the smoke is too thick, you evacuate yourself.

NARRATOR: Smoke can be even more dangerous than fire, as this crash test demonstrates. As the remotely controlled airliner hit the ground, the fire retardant fuel being tested failed. Cameras recorded what happened inside the cockpit and cabin when the plane was engulfed in fire. Although flames briefly entered the broken fuselage, instruments recorded life-threatening levels of toxic smoke.

RICHARD HALLION: You have here some products, some cyanide products, for example, things like this that are extremely toxic, extremely poisonous, and almost immediately act almost like a poison gas in, say, the World War I context in terms of preventing a person from performing in any sort of satisfactory manner.

NARRATOR: When plastic interiors and foam seats start to burn, poisonous fumes build up rapidly inside the cabin. A few seconds delay in evacuating a plane can make the difference between life and death. This accident in Manchester, England in 1985 left no doubts about the lethal effects of toxic smoke. The plane, carrying 130 passengers, caught on fire during take-off. During the emergency, one exit was blocked. But the other three were open with escape chutes deployed. There should have been enough time to evacuate everyone. But 55 people died. Most of them had collapsed after inhaling toxic smoke. The entire airline industry was shocked by what should have been a survivable accident.

HELEN MUIR: When the fire came in through the back of the cabin, and people started to see the smoke and so on, many people rushed as rapidly as they could, some of them going over the seats to the front of the cabin. And when they came up against what we call the bulkheads, which are those solid sections which are just in front of the galleys, and there, we have a quite narrow gap of actually 20 inches between those bulkheads. The passengers weren't able to get through as fast as they arrived, and we tragically finished up with a situation where some people just didn't manage to get through, and fell, and others moved on in spite of them.

NARRATOR: Helen Muir was asked to investigate by Britain's Civil Aviation Authority. She set up a series of trials designed to induce the chaos of a real evacuation. To do that, she offered a financial incentive to be the first off the plane.

HELEN MUIR AT BRIEFING: . . . exits are used, will receive a five pound bonus payment immediately. And we have found that this does encourage people - (laughter) - to make their way fairly rapidly. And very interestingly, we have had survivors from accidents come and see videos of behavior in these experiments and say, "Oh, yes, you know, that is how it was."

TRIAL FLIGHT ATTENDANT: Undo your seatbelts and step out . . .

NARRATOR: The trials were conducted in an old airliner to see how different cabin layouts affected the flow of passengers. This research video shows how bulkheads can cause blockages. A recommendation was made that the opening be increased to 30 inches.

TRIAL FLIGHT ATTENDANT: Take it easy! Watch your head!

NARRATOR: The researchers also experimented with different seat layouts and suggested widening the access to over-wing exits. The openings were so narrow that people became jammed. In this trial, firemen had to intervene to unblock the exit. The findings were published. But few major changes were made.

HELEN MUIR: There were some feelings in certain parts of the world that that Manchester could have been one-off. But then, some years later, in Los Angeles, we had an accident where again, we had a narrow-bodied aircraft which caught fire. And tragically again, we had a situation where the passengers had problems getting out of the over-wing exit, and again, it eventually became blocked.

NARRATOR: In Los Angeles, the USAir Boeing-737 crashed into a building, blocking half of its emergency exits. Twenty of the 80 people on board were overcome by smoke and died before they could exit the plane. Even in the wake of these accidents, the airline industry has resisted change. Increasing the number of emergency exits means fewer seats - and fewer paying passengers. Muir has also focused on other ways of improving evacuation times without redesigning the planes. The performance of cabin staff in an emergency can dramatically affect the number of survivors.

TRIAL FLIGHT ATTENDANTS: Undo your seatbelts and come this way! Right. Come on! Wait, wait, wait! Stop! Go now!

HELEN MUIR: There's no doubt good, assertive cabin crew who can rapidly mobilize people and manage them so we don't have pile-ups, make a tremendous difference.

TRIAL FLIGHT ATTENDANTS: Wait! Jump! Jump! Jump!

NARRATOR: By aggressively directing, even pushing the passengers, the flight attendants can evacuate the aircraft much faster. In a burning plane, this could save the lives of dozens of people. In some trials, Helen Muir increases the realism by adding smoke and switching off the cabin lights. This is how most crashes end up.

HELEN MUIR: I think it is difficult to survive in a dark or smoke-filled cabin. And the main reason is because most of the time, we use our eyes to find out where to go. And if a passenger wants to know what they need to do in order to survive an emergency, I think the key thing, in addition to listening to the briefing, is when they sit down, to look in front and behind them and locate their nearest exit, and then think about how they would get there. Would they go over seats? Or would they go around through the aisles? And in either scenario, count how many rows of seats they would have to pass so that they know in their heads where the exits are, and in the event of a fire and smoke, they would still know where to go and how to feel to get there.

NARRATOR: Researchers like John Paul Stapp have dedicated their lives to proving that crashes are survivable. In military aviation, such knowledge helped pioneer extraordinary advances, enabling jet pilots to escape certain death. In air travel, as in other forms of transport, accidents will continue to happen. How to make them survivable is a question that continues to haunt aviation.

What do you need to know when accidents happen? Be prepared. Log on to NOVA's Web site, www.pbs.org.

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