♪♪ -May 6, 1937...

The world's largest airship, the Hindenburg, explodes.

36 people are killed, and the entire disaster is caught on film.

-Oh, my God!

-Shoot it!

Shoot it!

Shoot it!

-That image of an airship crashing into the ground, wreathed in flame, has become iconic.

-But how did it happen?

Brand-new research and recently uncovered documents have exposed a series of crucial errors leading up to the Hindenburg explosion.

From fatal decision making... -They took shortcuts because of the pressure they were under.

-Landing airships in thunderstorms is not a good idea.

-...to flawed design... -The outer cover is similar to the wings of a plane: if they're not right, the thing won't fly right.

It's that simple.

-...and intense demands from Hitler.

-The Nazi party saw this as an opportunity and invested millions.

-That would have put enormous pressure on the crew to perform perfectly.

-Critical mistakes that led to a fiery tragedy and the death of airship travel.

-This visual of this burning airship cemented the fate of this form of transport.

-You don't hear the word "Hindenburg" without thinking disaster.

-There's kind of no coming back from that.

-""Hindenburg's Fatal Flaws."

♪♪ -"Secrets of the Dead" was made possible in part by contributions to your PBS station from viewers like you.

Thank you.

♪♪ -In 1936, German airship manufacturer Zeppelin revealed what they believed was the future of air travel... An 800-foot-long airship called the Hindenburg.

-No airplane has ever been bigger.

No air balloon has ever been bigger.

-What the Zeppelin Company was doing was building something that was the size of an ocean liner and floating it in the sky.

-It's the size of almost three 747's lined up back-to-back.

That is how big we're talking.

-It's almost mind blowing to think that nearly 100 years ago we built the biggest thing that has ever gone in the air and flown.

-With a range of almost 6,000 miles, the Hindenburg could cross the Atlantic Ocean with ease... Germany to New Jersey took less than 50 hours.

The fastest ocean-going ship of the time took five days.

And when it came to travelling in style, nothing came close.

-Accommodations are provided for 50 passengers.

The dining room, drawing room, writing room are large and comfortable.

-This was an experience not dissimilar to first-class on an ocean liner, but in the sky -- so you had access to comfortable cabins, a lounge, fine dining in the restaurant.

-The Hindenburg has a promenade deck where people can wander around.

It had its own piano.

The Hindenburg was packed with luxury.

-The Hindenburg really offered that level of service that set the standard.

It showed that you can have a cruise line cabin in the sky.

-The rich and famous snapped up seats aboard the airship.

The Hindenburg became the crown jewel of the world's first commercial airship operator.

But just 12 months after its maiden voyage, disaster struck.

Following an Atlantic crossing from Frankfurt to America, the Hindenburg exploded... with 97 passengers and crew on board.

♪♪ ♪♪ -How did this tragedy happen to the Hindenburg?

The world wants to know.

-Today, more than 80 years later, the list of failures that led to the tragedy can be revealed.

The first mistake happened a year before the disaster... when the Hindenburg started commercial flights after only a handful of test flights.

-Today, the testing that is done on aircraft is done at the very tiniest scales.

Computer modelling, exactly what forces are going to go through each component of the aircraft.

By modern standards, the testing that was done on the Hindenburg was really not very adequate at all.

♪♪ -In 1918, World War I was over and there was a growing appetite for adventure in Europe and the United States.

-Travel across the Atlantic and across the world at this point was becoming increasingly common, but it usually took place on ocean liners -- but it was slow, crucially, it was slow.

It took it could take up to up to a week or more, in fact to across the Atlantic, so Europe and America still felt very far apart.

-The First World War supercharged aircraft development... but passenger planes capable of crossing the Atlantic were still years from becoming a reality.

Instead, the focus fell on a different type of aircraft -- one that had proven its long-range potential during the war.

-The Zeppelins were created to be used in military maneuvers.

Zeppelins were used by the Germans to bomb Britain to drop bombs on citizens and the cities beneath them.

-In a bid to conquer the oceans, the U.S., France, and Britain raced to build a new generation of airships that would carry passengers, not bombs.

But the post-war Treaty of Versailles kept the Germans, experts in the field, sitting on the sidelines.

-Immediately after World War I, the allies tried very diligently to stop Germany from rearming.

And that meant size of Army, that meant Navy, and that meant aircraft.

-To stay in business, Zeppelin -- the acknowledged world leader in producing airships -- sidestepped the rules.

They offered their expertise to international competitors.

-The Zeppelin Company is quite sneaky here.

They go to the Americans and say, "If we build you this incredible airship, will you allow us to keep our factory running?"

And the Americans go for this deal.

-So the Zeppelin Company clearly took advantage of the immediate allowance of continued production so that they could continue developing, continue perfecting, and basically restart their operation.

-When the restrictions were finally relaxed in 1926, Zeppelin immediately started production of its own airship, called the Graf Zeppelin.

The Graf Zeppelin was the largest and most modern dirigible in the world.

With her, Germany took the lead in the airship field.

-The Graf Zeppelin was the very first aircraft that was actually designed to go over an ocean.

-To showcase their latest product upon completion, Hugo Eckener, the head of the Zeppelin Company and a skilled airship pilot, embarked on a record-breaking flight.

-Hugo Eckener built the largest Zeppelin ever attempted in the world and, in an immense publicity stunt, flies it all the way around the earth.

And everywhere he goes around the world he's cheered.

This is what Hugo Eckener wanted.

He wanted something that the public would look up to -- literally look up to -- and be wowed.

People were still afraid of this.

I mean, this is a really terrifying idea to be up in the sky.

What happens if you lose power?

Can you crash?

I mean most people have never even been up in the air at this point at all.

So what he does is he takes the thing around the world and does a series of, basically, flights that show that it's viable.

-And that is, of course, what catapults Eckener to this position of enormous fame, is that he becomes a representation of this new age of dashing pilots.

They are the kind of knights of the sky.

-After Hugo Eckener had done his miraculous 'round the world trip, companies all around the world wanted to invest in airships and wanted Zeppelin to make them.

-After Zeppelin had successfully demonstrated the airship's potential, Eckener -- determined to be at the forefront of global air travel -- developed an ambitious plan.

His company would build an airship even bigger than the Graf Zeppelin.

It would be called the Hindenburg.

-This was Germany saying, "We're still a key player in the world, and we can do these incredible engineering feats."

-The Hindenburg is developed to show that we can actually fly people long distances, pay for it through ticket revenues, and he's effectively creating an airline industry where one had never existed before.

-On March 4, 1936, 14 months before the disaster, the Hindenburg was ready to take to the skies for the very first time.

But no one -- not even its engineers -- knew how something so large would behave once airborne.

-Despite the fact that the Zeppelin Company had had 25 years of success, the Hindenburg pushed things much, much farther than it had ever been done before.

-It was so much bigger than any airship that had come before.

And in engineering, when you start scaling things up, you do start entering problems.

Because of the vast size of the Hindenburg, they really didn't know how it was going to fly until they'd already built it and put it up for its first test flight.

-We're putting something up in the air that has some seven acres of aeronautical cloth.

The vast forces that are on it are inconceivable.

So how it's going to behave is not known and it makes you wonder if it wasn't just too big in the first place.

-The Hindenburg's first flight lasted more than three hours.

But the test flights were limited and inadequate, while critical safety checks were overlooked.

Zeppelin missed a possible chance to find and fix problems.

-To establish that a type of aircraft is safe, requires numerous tests: turning ability, stopping ability, ability to control altitude in flight, flight test crashes, how to have emergency evacuations -- so many things that ought to be in place.

Many of these weren't.

-They did seven test flights to make sure that it would actually be able to get airborne and do the job that they thought it could do.

Of these seven test flights, all of them were done above land in Germany.

None of them were testing actually what they were hoping to do with the Hindenburg, which was to fly it across the Atlantic.

-It is strange, isn't it, that flight tests for an over-ocean aircraft wouldn't include an over-ocean flight trial.

But this was the case back in the 1930s.

Remember, aeronautics is really new.

There's so many things that are unknown.

And this vehicle is so much larger than what had ever been tried before.

-After just a handful of test flights -- all performed over land -- the first passengers were welcomed onboard.

And then the Hindenburg set off on an epic 6,000-mile, four-day flight across the Atlantic, from Germany to Brazil.

-The Hindenburg, when it first took off, was completely an experimental aircraft and probably had no business taking passengers for a long time.

As an experimental aircraft, there were certainly issues that had to be worked out and it's clear from memos and letters back and forth in hasty fashion that they were devastating issues that had to be resolved quickly.

-The paying passengers on board the Hindenburg trusted German ingenuity.

They trusted that this airship would get them from A to B safely.

-Against the odds, the Hindenburg's first transatlantic flights were all successful.

But a year later, on its 37th Atlantic crossing, the airship's problematic size and inadequate testing became apparent.

-There was a design flaw -- critical and fatal design flaw -- on the Hindenburg.

♪♪ -As the Hindenburg was coming into land at Lakehurst Naval Air Station in New Jersey, it was consumed by flames.

The 7 million cubic feet of hydrogen inside the airship exploded almost instantaneously.

In less than a minute, the Hindenburg and its 97 passengers and crew were enveloped in a gigantic fireball.

-The technology that created the Hindenburg couldn't save it.

In 32 seconds, it went up in flames.

-The risk of using highly explosive hydrogen as a means to lift the ship was well known.

-Not all of the ships got off the ground -- the V6 exploded in its hanger.

The hydrogen had been ignited by a stray spark.

-But nearly a decade earlier, the company's headstrong boss ignored the concerns of key administrators, and it was a decision that would prove fatal.

-The risks are very high.

And the fact that there were alternatives available, even if they had their shortcomings, does suggest that the use of hydrogen in the Hindenburg did make this airship a ticking time bomb.

♪♪ -In the early days of designing the Hindenburg, company leader Hugo Eckener had a key decision to make... Would his ambitious airship rely on hydrogen gas to provide its lift?

Or should he switch to a newer, and safer, alternative: helium?

-You want to fill your airship with a gas that is less dense than the air around it.

This produces a buoyancy force which pushes the airship up.

Hydrogen is the lightest chemical element.

It's the smallest atom, it occurs naturally on Earth as a gas, and it's much less dense than air.

Helium is the second lightest gas.

The key advantage of choosing helium over hydrogen in an airship is the fact that it is an inert gas and so it doesn't represent an explosive risk.

-Hydrogen was cheaper.

It was more readily available.

It was capable of achieving a much greater lift so it could carry more passengers, more weight in the gondola, But the risk of it was it was flammable, highly flammable.

-Helium was likely a much safer, and more stable, option than explosive hydrogen.

But helium had problems too.

While also lighter than air, it was still heavier than hydrogen, reducing its lift power and the number of passengers.

And it was difficult to get ahold of.

In the 1930s, most of the world's helium was produced in the United States.

-The U.S. had a monopoly on helium supply.

This presented a big problem to the engineers in Europe, and they really didn't like the idea of relying on U.S. imports of helium.

-So a German company like Zeppelin couldn't realistically build helium airships without a huge amount of cost and a huge amount of potential paperwork and diplomacy trying to secure that gas from the United States.

-Hugo Eckener chose cost and availability over safety, forging ahead with the use of hydrogen for his new airship.

But then, in October 1930, seven years before the Hindenburg disaster, a tragic accident forced him to question his original decision.

-Most of these men have a date with death... but in the elevator up the mooring mast there's no hint of the holocaust to come.

-A British airship filled with hydrogen, the R101, exploded, killing 48 of its 56 passengers.

-And this was all that remained of Britain's empress of the sky.

-After the R101 flaming disaster, Hugo Eckener thought maybe we do need to use helium.

-You give us helium for our merchant ships and we will give you our large operating experiences in exchange.

And this way I believe the further development of the airship and airship traffic will be assured for the benefit of mankind.

-But, ultimately, Eckener continued to rely on hydrogen.

Zeppelin had an unblemished record of using it in all their previous airships.

Overconfident, Eckener ignored the warnings and made the fatal decision to stick with the explosive gas.

-The historical record shows that no one told Hugo Eckener what to do.

He was absolutely bull-headed in his determination to stay with hydrogen at all costs.

-Hugo Eckener boasted about Zeppelin's safety record.

He boasted that German ingenuity could master the hydrogen and that they could produce the best airships in the world.

It was this kind of arrogance, unfortunately, that led to the disaster.

-The decision to stay with hydrogen meant that the Hindenburg was certain to blow up fatally at some point.

-Had Eckener heeded the warnings about using hydrogen, the Hindenburg would never have exploded.

But his choice wasn't the only mistake that set the airship on the path to disaster.

♪♪ For the Hindenburg's maiden crossing, the passenger list was made up of celebrities, the wealthy elite, and journalists.

But now, new evidence reveals that even as these people were boarding, a critical design flaw meant the Hindenburg's time was already running out.

-The Hindenburg had a dangerous rattle -- and this is a problem, and they know it.

♪♪ -December 1935... almost 18 months before the disaster.

Zeppelin technicians were about to undertake one of the most difficult steps in of the Hindenburg's construction: Covering its vast aluminum frame with fabric.

-The outer cover of the Hindenburg is one of the most extraordinary uses of fabric, probably of all time.

We're talking about some seven acres of cloth.

-It was stretched across this skeleton of metal, and this was really important that the that the textile was fitted really snugly because if there's any sort of movement in that, then the ship won't be able to fly efficiently.

-This highly skilled process was unique to Zeppelin, and it had been perfected by the company's textiles expert, Karl Hurttle.

Hurttle spent two decades overseeing the covering of more than 50 of Zeppelin's airships.

-Karl Hurttle was sort of a secret weapon of the Zeppelin Company.

He's really the world's expert on this.

-He had developed his own system for creating a taut layer of waterproof fabric for the airship's vast skeleton.

-This is an incredibly involved process.

But in the end, what they end up with is something that is very strong, very sturdy, and doesn't vibrate in the wind.

-But when the Hindenburg was ready to be covered... Karl Hurttle wasn't there.

He was now working in the United States.

With financial pressure to get the Hindenburg airborne, Zeppelin was forced to cover the airship without its most experienced fabric expert.

-This type of construction had never been attempted before.

This was the biggest airship ever made.

And so the fact that their chief textile engineer was away overseas on a different project was really, really not ideal.

-And the colossal size of the Hindenburg wasn't the only challenge for the technicians.

-The conditions were bitterly cold and wet.

This meant that the textile became waterlogged and icy, and this caused the textile to become very stiff and not very flexible.

-It's like trying to put a dress on or a pair of jeans that are frozen.

They're just not going to quite fit on there.

And in fact, there was a Goodyear technician on hand who observed the outer cover being put on the Hindenburg -- first time it was ever done -- who noted that, probably, given those conditions -- the freezing weather and the dampness -- that the outer cover was not going to be properly put on as firmly and tautly as it should be.

-When the Hindenburg was finished, it took its first test flight on March 4, 1936, with just a handful of crewmembers aboard.

And within minutes, they detected a problem.

-Once it was up in the skies, they noticed a sort of fluttering of this textile that was coating the Hindenburg.

What they didn't realize was that this fluttering was being transferred to the metal skeleton of the Hindenburg.

-Back in the hangar, the technicians desperately searched for a solution.

They attempted to make the outer cover fit more tightly by applying a highly flammable fabric lacquer known as "aircraft dope."

-One of the things that the Zeppelin Company did was to paint two extra coats of dope across the entire top.

Now, this is a significant amount of weight and a lot of expense, but the hope was that this would remove the potentially destructive flutter.

-Despite these attempts to fix the problem, the fabric continued to flutter.

But the added drag and constant vibrations didn't seem to affect the airship's overall flight performance, so the problem went unsolved.

The fluttering fabric would play a more significant role in the Hindenburg's destruction than previously understood.

-This issue of fluttering in an airship was well known on the smaller ones that had come before.

The difference with the Hindenburg was that it was on a vastly larger scale, so the problem became amplified in the same way that the volume of the ship was amplified as well.

And so it wasn't known how much of a problem a large flutter would be with the Hindenburg.

Without that fluttering, it's possible that the Hindenburg disaster could have been entirely avoided.

[ Explosion ] -Just moments into the Hindenburg's maiden flight, concerns about its sloppy construction were raised.

But the reason for its rushed construction happened five years earlier and affected millions of people.

-In 1929, the Wall Street crash had taken place in the United States, and that unleashed the worldwide Great Depression.

So funding for large-scale industrial and technological enterprises began to wither away.

-Germany's economy was on its knees -- and Hugo Eckener was worried about his budget.

Determined to keep his ambitious airship on track, he brought in financial investors who sealed its fate.

-Trying to build the largest aircraft the world has ever seen in the middle of the Great Depression was not good timing.

That meant that in order to salvage the project, he had to cut some deals with the devil.

♪♪ -In the summer of 1933 -- four years before the Hindenburg exploded -- Eckener appealed to Hitler's propaganda minister, Joseph Goebbels, for financial help to finish the giant airship.

Goebbels jumped at the opportunity.

-So the Hindenburg was seen by Nazi party leadership, particularly Joseph Goebbels, as a massive propaganda coup.

Airships were this symbol of greatness, of technological progress, of luxury.

-To finish the pioneering airship, the Nazi regime invested funds totaling the equivalent of more than $10 million today.

-There's no such thing as a free lunch, and the money that the Nazis gave had strings attached.

-After five years of construction, the Hindenburg was finally finished in March 1936.

Goebbels almost immediately put his propaganda machine to work, emblazoning the ship with Nazi swastikas.

Instead of test flights over the open ocean, he commandeered the airship for short publicity flights over Germany to increase Nazi popularity.

-The Hindenburg became the means by which the Nazis promoted their philosophy to the skies.

-The Hindenburg became this symbol of Nazi Germany in many respects, and that would have put enormous pressure on the Zeppelin Company and on the crew of the airship to perform perfectly.

[ Cheers and applause ] -The Hindenburg became a stand-in for Nazi Germany's technical prowess and mechanical expertise... without ever being properly tested for long-range flight.

-We can see here the ways in which this new technology has been appropriated by the Nazi party who helped to fund it.

Before it's even had a chance to serve its commercial purposes, it's already being deployed as a propaganda tool for the Nazi regime.

-The Zeppelin Company took shortcuts.

They took shortcuts because of the pressure they were under.

There was too much support behind it for it to fail.

-Keen to start making money on their investment, Zeppelin scheduled the Hindenburg's first commercial flight.

But the limited safety testing... ill-fitting outer covering... and pressure from the Nazis to showcase perfection... left the Hindenburg compromised.

It was only a matter of time before the shortcuts were revealed.

To this day, the Hindenburg remains the largest aircraft ever flown.

The airship was the culmination of a movement toward lighter-than-air transportation that began eight decades earlier.

In 1852, the world's first airship, built by French inventor Henri Giffard, flew a distance of more than 20 miles.

But it was German inventor Graf Von Zeppelin who, in 1900, successfully demonstrated the real potential of the motorized airship.

-It was a transition from simply getting up into the air and being able to move where the wind took you, to getting up into the air and steering against the wind, which is a big, big step in aviation.

-The secret to Zeppelin's concept lay inside the ship's protective fabric covering: A series of gasbags provided the airship with enough buoyancy to carry an engine... and a payload.

-Of course if you've got a lot of gas balloons, you've got a lot of payload, so you can carry a really big engine.

You can have multiple propellers, and that that was his breakthrough.

-Zeppelin demonstrated that air travel could be more than a recreational activity for adventurers and thrill seekers.

The airship had the potential to be used for a great deal more.

-And this is really where the Zeppelin makes its mark, because it's really the first craft that can reasonably and predictably steer where it wants to go, take off where it wants to go, and land where it wants to go.

Remember, this is a time when no one had ever been sort of air lifted up and suddenly looking down on the world.

So this was quite a novelty at the time - and that was the plan after the war, was to create a passenger service for an airline.

-By the time disaster struck in 1937, the Hindenburg had already delivered on its promise to be the world leader in international aviation.

In its first nine months, it made 34 successful Atlantic crossings... and flew almost 3,000 passengers between Europe and North and South America in record time.

-It's been an incredible season.

200,000 miles, not a single problem.

-But the Hindenburg's shimmering canvas was hiding a deadly problem.

One of the giant gasbags, containing the highly explosive hydrogen, was on the brink of rupturing... and no one had noticed.

-Any leak of hydrogen on an airship is potentially fatal.

If you have gasbags that are damaged, there's no telling how much hydrogen can escape.

It's clearly a catastrophic problem.

♪♪ -In December 1936 -- five months before the Hindenburg exploded -- the colossal airship was undergoing its first major overhaul.

After a triumphant first year, 10 new cabins were installed to increase the airship's capacity and help make the Hindenburg profitable for the first time.

-They proved the concept that luxury travel was possible, they could do the distances, that people wanted to do it.

There was massive demand and they could do it in luxury, but they just couldn't make money.

-To create the additional cabin space, the shape of one of the airship's 16 hydrogen gasbags had to be changed.

-It's like altering a dress or a jacket.

They needed to refit this gasbag for additional passenger cabins.

-A maintenance report -- only recently discovered in the archives at the University of Texas at Dallas -- documents how, during the remodeling process, an alarming problem was discovered.

-When the workmen pull the gasbag out, they discover chafing abrasions at the top of it that made it vulnerable to a leak.

-Once again, the airship's ill-fitting outer skin was the source of the trouble.

The vibrations caused by the fluttering fabric loosened the wires that kept the gasbag in place.

In turn, those wires then rubbed against the cotton fabric of the gasbag, wearing it dangerously thin.

-Some protective wiring that was supposed to increase the safety of the gasbags actually was having the opposite effect.

-And so by compromising the structural integrity of those gasbags, that's representing a risk point of hydrogen potentially leaking out.

-The same maintenance report goes on to reveal that, although the damaged gasbag was fixed, the wires meant to hold it in place were simply tied back and not properly secured.

-It's incredible that the best solution that they could come up with for a technological wonder was tape and twine.

In the end, clearly, it didn't work.

-This, to me, seems like a little bit of a patch solution, considering that the hydrogen gasbags are so important and their integrity is pretty crucial to the safety of the aircraft.

-The damage may have been patched up, but the Zeppelin team was still no closer to resolving the issue with the airship's fluttering fabric.

-They thought that they'd limited the extent of the damage, but why it was happening was still a puzzle that they were intently working on.

-Just days after the potential hydrogen leak was fixed, the Hindenburg began the countdown to its second season.

The airship's design flaws and makeshift repairs had turned it into a ticking time bomb.

And one senior member of the Zeppelin team realized just how dangerous it had become.

But he chose to keep quiet.

♪♪ For the fateful 1937 season, the Hindenburg would be flown by several different captains.

Each one had been personally trained by best in the business.

-Ernst Lehmann was the most experienced Zeppelin pilot in the world.

He flew through World War I.

He was trained by Hugo Eckener.

Lehmann is one of the chief pilots for the Hindenburg.

He knows it, every inch, bow to stern.

-Now, a letter, recently discovered in the records of the Bureau of Air Commerce, shows Lehmann knew about the damaged gasbag... and the shoddy repairs.

-He told a good friend of his named Leonhard Adelt, who was a journalist, that he had very deep worries about the Hindenburg because of the gasbag damage.

This is very secretive information.

This is not well known outside the company and barely known inside the company.

So he's really confided something in someone he really respects and trusts.

-Written by Leonhard Adelt, the letter reveals that Lehmann was prepared to make a major personal sacrifice to prevent disaster.

-Lehmann tells Leonhard Adelt, "I'm so worried about this that I will fly on the Hindenburg because there may be a problem and the experience of the staff and the crew won't be enough to handle it.

I will be there to help."

We never knew this.

This was an incredible admission by Captain Lehmann of a real problem on the Hindenburg.

-On May 3, 1937, Lehmann boarded the Hindenburg for what would be its final flight.

-It's clear from the fact that Lehmann agreed to fly on the final flight that he expected some sort of problems, but ones that could be manageable.

I don't think he anticipated catastrophe.

I think he thought difficulty, grave difficulty, but not catastrophe.

-By noon on May 5th -- the day before the crash -- the Hindenburg was 1,000 miles from its destination... which would play its own key part in the airship's destruction.

-The reason they chose Lakehurst was proximity to the cities, but it's prone to sea fog and it's prone to other bad weather phenomena.

So it's actually a rotten place to build an airship base.

♪♪ -Nearly 20 years earlier, when many believed the airship was the future of international travel, the U.S. Navy built a new facility in Lakehurst, New Jersey.

They spent the equivalent of $140 million, hoping to make a profit on this new form of transportation.

-The Lakehurst base was absolutely the pinnacle of airship development in the United States.

It had the largest airship facility in the world.

It was, in fact, the largest room ever constructed in the world in order to house these enormous airships.

-In the same way that the Hindenburg was a flagship for German airship engineering, so Lakehurst was a flagship site for the U.S. kind of investment in airships ships as well.

-But despite its impressive infrastructure, there was a major problem with the site.

Lakehurst was a terrible location, exposed and prone to bad weather coming straight off the North Atlantic.

-The optimal placement for safety and function of any airship base is a hundred miles inland.

Lakehurst was 14 miles inland.

-The Lakehurst airbase was renowned for being troubled by storms -- not an ideal scenario if you trying to land an airship that is filled with hydrogen gas.

-In 1927, nearly 10 years before the Hindenburg disaster, an American airship, the USS Los Angeles, was caught by a gust of wind.

A photographer captured the incredible moment on film.

-At Lakehurst, the Los Angeles has its tail turned vertical by the strength of the wind.

-It makes the airship stand fully up with people inside.

People are falling down, things are crashing down, gasoline's flooding down.

And only after several minutes did the air breeze stop and it dropped back down onto its side.

-I think it's fair to say that it was not the ideal location for an airship base, in a place that was constantly buffeted by storms, both in terms of strong winds and in terms of thunderstorms with electrical charge.

-Despite concerns after the USS Los Angeles incident, the Navy's financial investment in Lakehurst kept the facility open.

And the decision seemed like a smart one.

For the next 10 years there were no major incidents.

Until May 6, 1937.

At 11:30 AM, on the day of the Hindenburg disaster, the commander of the U.S.

Naval Air Station received a disturbing weather report.

Flying conditions in the area were described as "average to undesirable."

The Hindenburg was just six-and-a-half hours away from its destination.

Approaching the east coast of the United States, the Hindenburg was already behind schedule, delayed by a strong headwind.

This delay to the Hindenburg's arrival in New Jersey would prove to be deadly.

-There was actually a one-hour window when the weather was completely clear over Lakehurst, meaning that the Hindenburg could have landed in perfect safety had it have been there at that time.

♪♪ -The Hindenburg had been scheduled to arrive at Lakehurst airship base at 6:00 AM.

But the winds had cut the airship's speed almost in half.

-The Hindenburg normally travels at 70 miles per hour at a cruising speed.

It's down to 55.

Within a day, it's down to 37.

It's barely moving.

The outer cover is fluttering tremendously and taking the brunt of all these heavy headwinds.

-The Hindenburg had been delayed on its journey, so the captain had radioed ahead to the base to tell of this delay -The landing was rescheduled for 6:00 PM and the ground crew was ordered to stand down until then.

But, as the Hindenburg approached the U.S. coastline, the winds dropped and the airship began to make up lost time.

At around 4:00 PM, the Hindenburg was finally approaching Lakehurst.

Conditions were unsettled, but a short break in the weather provided an opportunity to land.

But now there was another problem.

Because the Hindenburg's speed had increased, the ship was now two hours ahead of its revised time of arrival and the ground crew was nowhere to be found.

-Generally, an airship would take over 300 people to bring it in, people who are literally pulling on ropes that are going up to the ship and helping bring it back to the ground.

-It becomes a huge operation, but also one that's only ever rolled out at a time when an airship is coming in.

-With the ground crew not scheduled to return to the base for another two hours, the Hindenburg was forced to wait.

-The Hindenburg ended up circling around the base for a while, while the ground crew scrambled themselves together and got ready for the landing.

[ Thunder rumbles ] -But as the Hindenburg stayed in its holding pattern, the weather grew much worse.

-Landing an airship is difficult in the best weather conditions, but here we have churning skies, there had been thunderstorms throughout the area all day.

-At 5:12 PM, Lakehurst base commander Charles Rosendahl finally gave the Hindenburg clearance to land.

-Rosendahl said, "Weather conditions have settled, recommend landing."

-But he had badly misjudged the weather.

Using radar to forecast the weather was still years away.

The airbase relied on basic meteorological instruments and ground observers.

By the time the Hindenburg was in position to land, the storm was directly over the base.

-There was thunder in the air.

There was dampness in the air.

There was lightning around.

They weren't very good conditions.

They shouldn't have landed when they did.

-If the Hindenburg had waited out the storm away from Lakehurst, there was still a chance disaster could have been averted.

But that would have delayed the return journey back to Europe... which was not acceptable for brand Hindenburg.

-There was enormous pressure to land the ship and take off as quickly as possible, because it was completely booked with 70 passengers who were headed off to Europe, which meant the ship was being steered into disaster.

-The Hindenburg was the world's first regular transatlantic passenger air service.

But on its final flight, it was running half-a-day behind schedule.

A series of mistakes were already conspiring against the airship... And now there was added stress.

[ Thunder rumbles ] -Landing airships in thunderstorms is not a good idea -- but one of the major contributors to them landing when they did was the pressure that that particular flight back was a very, very important for them.

♪♪ -The Hindenburg was marketed as a luxury passenger service that prided itself on punctuality.

12 hours behind schedule, there was a great deal of pressure to land the airship, regardless of the weather conditions.

-The Zeppelin Company, for obvious reasons, were very keen to minimize any delay in the functioning of their flagship craft to showcase once again that the Hindenburg was the best of its kind.

-A normal turnaround took two days.

Because of the delayed arrival, the crew would not have had enough time to prepare for the return journey.

-The pilots can be under stress to get their passengers to the destination on time, so when things like weather come into play, they now have to battle against this.

-The boss of Lakehurst was under this political pressure, and the captain of the Hindenburg was under political pressure, to get on with it.

-This return trip was especially important for the Zeppelin Company.

Many of the passengers booked on the return flight were VIPs heading to the social event of the year: the Coronation of King George VI.

-There were dignitaries and luminaries who were expected to travel on the Hindenburg.

They were waiting and relying on the fact that this new means of safe transportation would get them back to Europe.

-The coronation of King George VI is an enormous event on the world stage.

It's being covered, of course, by the press in an absolute frenzy, not only because it's the coronation of a new king in Britain, but also because of the scandal around the abdication of King George VI's older brother, and his marriage to the divorcée Wallace Simpson, in the run up to this coronation.

So there's more media attention than ever before in the British royal family and in the coronation.

-There must have been enormous pressure after the flight delays to land the aircraft and to turn it around to get on the way with the next flight, which was highly publicized.

-The pressure was mounting -- a lengthy delay... no ground crew... a vital return journey in jeopardy.

Against standard airship operational practice, the decision was made to land as the storm overhead grew in intensity.

It was the single biggest mistake leading up to the tragedy.

-If you're coming in to land in an atmosphere that is electrically charged, that represents the potential for a spark and that can be your ignition source for a hydrogen explosion.

♪♪ -To decrease the airship's buoyancy, the Hindenburg crew began releasing hydrogen from the gasbags.

But above them, the gathering storm clouds filled the air with a deadly electrostatic charge.

-The way in which an airship lands is it purposely vents out hydrogen into the air.

If you know that you're venting out hydrogen, though, you cannot have any possibility of lightning in the sky.

That's why weather is so critical.

-As the Hindenburg descended, the crew realized the airship was no longer level, the tail lower than the bow.

-They felt kind of a jolt.

Something was off.

The tail of the ship felt heavy, which means it felt like it had lost some hydrogen.

It starts to sink.

-Trying to get the airship level, the crew released more than a ton of water from the ballast tanks, drenching the ground below.

The airship steadied... but it was no longer in position to land.

The captain then attempted to steer the Hindenburg back with a drastic maneuver: a tight turn at full speed.

-He came in and did that tight turn, which he shouldn't have done, to get the ship down on the ground and get the passengers swapped over, to prove that they were running on schedule.

-At the time, experts believed the sharp turn started a deadly chain reaction.

Excessive flexing of the Hindenburg's internal aluminum frame may have caused the botched repair to the wires surrounding the gasbags to come undone.

-The Commerce Department, which investigated the case back in 1937, believed that a sharp turn in the final landing maneuver caused a bracing wire inside the ship to break and tear into a gasbag.

-But Michael McCarthy suspects the gasbag wasn't ruptured as a result of the tight turn.

He believes the gasbag was already leaking, which would explain why the tail of the ship lost buoyancy and started to sink.

-What's more likely is that the gasbag had been damaged in heavy headwinds, which delayed the ship for so many hours and finally created a hydrogen leak inside the top of the ship.

-Even as the Hindenburg was lined up with the landing mast, it may have already been leaking hydrogen.

Then, the captain made yet another disastrous decision.

-There was a high landing technique and a low landing technique.

But the decision was taken to do the high landing.

That meant that the airship had in its nose two ropes which dropped for the ground crew to catch hold of.

-At 7:21 PM, as the rain started to fall, the first landing rope was lowered.

The ground crew was able to take control of the Hindenburg sooner, while it was still more than 200 feet overhead.

But it might also have exposed everyone to a new danger.

-All airships, when they fly through the air, they get a static charge just from the air, and the ground crew know that you don't grab the rope straight away because you can get electric shock as the charge on the surface of the ship travels down.

-As the Hindenburg came into land, these landing ropes were wet and so able to conduct electricity.

So you had the metal skeleton of the Hindenburg, which was then connected to the earth via an electrically conductive rope.

-Just four minutes after the first landing ropes reached the rain-soaked ground, tragedy struck.

The Hindenburg burst into flames.

Even today, no one knows whether lightning or a static spark caused the hydrogen to ignite.

62 passengers and crewmembers miraculously made it safely out of the fireball.

But 36 people were killed... some instantly, while others died later from their injuries.

Ernst Lehmann, the pilot on board who hoped to prevent a potential disaster, died the day after the crash.

-Of the people who died, most of them were killed by gravity.

Because they jumped out when the airship was still up in the air.

-The Hindenburg's horrible end has shocked the entire world.

-The ensuing investigation suggested pilot error was to blame.

But today, the newly found maintenance report and letters suggest the ill-fitting outer cover sealed the Hindenburg's fate long before its final flight.

-The historical record with Zeppelin suggests that had they been able to fix the fluttering outer cover so that the gasbags were no longer damaged, the Hindenburg disaster would never of happened.

-No single error caused the events of May 6, 1937, to happen as they did.

Instead, a raft of fatal flaws led to the destruction of the world's greatest airship.

-The fact that the thing blew up and was captured by the media ended up searing it into our imagination.

-That image of an airship crashing into the ground, wreathed in flame, has become iconic -- has become an enduring image, I think, of the early 20th century.

-To see that caught on camera, it's quite a devastating moment that would shock anybody.

There's kind of no coming back from that.

-It had never been seen before -- such a destructive fire, such a destruction of people, passengers, and an aircraft.

-When the Hindenburg burst into flames and fell from the sky, this brought the death knell to the golden age of the airship.

♪♪