The Hindenburg disaster occurred on 6 May 1937 when the German Zeppelin airship LZ 129 Hindenburg attempted to land at Lakehurst, New Jersey, but burst into flames. The airship's gas cells were filled with highly flammable hydrogen gas, and the Hindenburg crashed to the ground in just 32 seconds. 35 people on board and one member of the ground crew died in the disaster; there were 62 survivors. Although the cause was never determined, the tragedy and the fact that it had been captured on film, which was shown in cinemas worldwide, ended the use of hydrogen airships to carry paying passengers.

With the success of the LZ 127 Graf Zeppelin airship, which provided a passenger service between Europe and the Americas from 1928, the Zeppelin company began to design an even bigger airship, the LZ 129. Constructed at Zeppelin's headquarters in Friedrichshafen, Germany, from 1931 to 1935, the new craft became the property of a new company, the Deutsche Zeppelin Reederei (DZR), which had involvement from both the airline Lufthansa and funding from the German state (which was controlled by Adolf Hitler and the Nazi Party from 1933). LZ 129 made its maiden flight on 4 March 1936. The new name Hindenburg, in honour of the late president of Germany, Paul von Hindenburg (1847 to 1934), was soon emblazoned on the side of the hull in large red Gothic script. The Hindenburg's first Atlantic crossing began on 31 March 1936, flying from Friedrichshafen to Rio de Janeiro, Brazil. The first flight to New York was made from 6 May and took just 61.5 hours. The Hindenburg would make nine more flights to New York and six more to Rio before the year was out.

The Hindenburg measured a massive 804 feet (245 m) in length, which made it almost as long as the RMS Titanic and three times longer than a modern Boeing 747 airplane. The airship's internal frame had a maximum diameter of 135 feet (41.2 m). Inside the cotton outer skin were 16 gas cells, with a combined capacity of 7 million cubic feet. Originally, it had been the intention to fill these cells with helium gas rather than flammable hydrogen gas, but the world's only source at the time was the United States, and its government decided not to supply helium since it was concerned the Hindenburg might be used for military purposes. The airship had four Daimler-Benz engines, which provided 3,600 hp and produced a top speed of 68 mph (110 km/h). Lateral steering was provided by a wheel with a gyro compass, while another wheel controlled the airship's elevation. The airship had a range of 10,250 miles (16,500 km).

The Hindenburg's captain controlled the airship from the gondola beneath the vessel, but passengers were accommodated within the two-deck structure built within the hull. There was room for 50 passengers inside 25 double-berth cabins. Besides the bunk beds, each cabin was equipped with a folding sink that provided both hot and cold water. There was a fold-down table and stool, but no window. Ten more cabins were added later, including a four-berth one, and so the total passenger capacity was raised to 72.

On either side of the central block of cabins were public areas, which included spacious and comfortable lounge and dining areas with massive windows that sloped significantly outwards to maximise the view. The Hindenburg usually flew at a low altitude of 650 feet (200 m), which gave wonderful views of the landscapes below or ships crossing the ocean. There was a writing room with a small library, a shower room (passengers had to pre-book slots to use its rather weak shower head), and a pressurised smoking room with an airlock door for safety (to keep out any stray hydrogen gas). Passengers had to fight for a single electric lighter within the smoking room. One could also receive a drink in the smoking room, including the LZ 129 Frosted Cocktail: gin with a splash of orange juice. Another attraction to the smoking room was the plexiglass windows set in the peachwood flooring that gave a dizzying view of the passing world below.

Furniture was in the modern minimalist style, while the walls were decorated with murals of the history of flight and postal services, and in the lounge area, a large illuminated map of the world showing the various Zeppelin routes. There was central heating, four toilets, and a room of urinals. The crew of 40 worked, slept, and ate four meals a day on the deck below. Food for everyone on board came from a kitchen equipped with a stove with four electric rings, roasting and baking ovens, a refrigerator, and an ice machine. Dishes were delivered to the passenger deck using a dumb waiter. "On a typical Atlantic crossing the chef went through 440 pounds of fresh meat and poultry, 800 eggs and 220 pounds of butter" (Archbold, 155).

With a one-way, all-inclusive ticket on the Hindenburg costing $400 (the price of a car at the time but still cheaper than a first-class ticket on the best ocean liners), passengers carried with them limited luggage (66 lb or 30 kg) but weighty expectations of an unforgettable flying experience. Every detail, from fine Zeppelin-branded china crockery to the silverware, fresh flowers, and art deco light fixtures, was considered to give a distinct air of luxury. Passengers could even leave their shoes outside their cabins at night and find them freshly polished in the morning. Another service was a special post with letters franked "via the Hindenburg". There was fine cuisine (trout, venison, vintage wines, and champagne), and entertainment was provided by a Blüthner baby grand piano, specially built from lightweight duralumin. Passengers, who came on board via a stairway beneath the airship, received a helpful booklet, Airship Flights Made Easy, which reassured them of the comforts available but also reminded them not to throw things out of the windows, not to use matches or lighters outside the smoking room, and not to leave the public areas without supervision from a crew member (guided tours within the hull were possible). Passengers marvelled at how quiet the engines were and how smooth the trip was. The journalist Louis Lochner noted in his diary: "You feel as though you were carried in the arms of angels" (Archbold, 162).

The Hindenburg made 17 return trips across the Atlantic in its first season, carrying a total of 1,600 passengers and flying a total of 200,000 miles (322,000 km). Despite the high operating costs, the Hindenburg almost broke even in its debut year, and another 18 transatlantic flights were scheduled for 1937. Carrying mail and small but valuable cargo and participating in air shows were lucrative sidelines for the owners. The Nazi Party was keen to use the Hindenburg for propaganda purposes, and the airship, emblazoned with swastikas on its tail fins, dropped thousands of pro-Nazi leaflets over many different cities during a national referendum, flew over Berlin at the opening ceremony of the 1936 Olympic Games, and made a spectacular appearance at the Nuremberg Rally that year.

In 1937, travel by airship seemed to have a long and secure future, but the public's passion for the Zeppelins was about to be extinguished by a terrible disaster. The Hindenburg set off from Frankfurt for New York on 3 May 1937. The airship was carrying 36 passengers and a crew of 61, larger than usual because there were several trainees who were scheduled to serve on a new airship under construction, the Graf Zeppelin II. The airship faced strong headwinds, which meant it would miss its planned 6:00 a.m. arrival time. The captain, Max Pruss, radioed the landing ground at Lakehurst that he would arrive at 6:00 p.m. instead. The airship managed to make up some lost time and actually arrived around 4:15 p.m., but by now the landing crew (which consisted of 228 people) had been prepared for 6:00 p.m., and so Pruss was obliged to move the airship to the southeast. A weather front with rain and thunderstorms was moving towards Lakehurst, and an early landing would have perhaps avoided the tragedy that followed.

Pruss waited until a heavy squall had passed and then brought the Hindenburg in for landing just after 7:00 p.m. on 6 May. Coming into the wind, the airship descended to around 700 feet (210 m) from the mooring mast. Lines were then dropped to the awaiting ground crew, who secured them and began hauling the Zeppelin closer to the ground. A few minutes later, with the airship just 260 feet (80 m) above the ground, a small flame was spotted at the top rear of the Zeppelin's hull. Within seconds, the fire spread as the hydrogen gas cells ignited in a domino effect. Commander Charles E. Rosendahl, in charge of the ground crew, describes below what he saw at that moment:

It was a brilliant burst of flame resembling a flower opening rapidly into bloom. I knew at once that the ship was doomed, for nothing could prevent the flame spreading to the entire volume of hydrogen with which she was inflated. There was a muffled report and the flames spread rapidly through the after quarter of the ship.

(Christopher, 130).

Other eyewitnesses spoke later of seeing the outer skin of the airship flutter just before the flame appeared, while others reported hearing a pop sound rather than an explosion. The airship dropped rear-first towards the ground as the fire raged forward. Those on board were hurled backwards, and a terrific shudder ran through the entire airship. As the Hindenburg settled towards the ground, those passengers and crew who could climbed down tethering ropes or leapt out of doors and windows, many with their clothes on fire.

In just 32 seconds, the entire airship was incinerated into a gigantic pile of twisted metal. Besides the friends and relatives waiting to greet the arrivals, the dreadful scene was witnessed, photographed, and filmed by members of the press who were there to cover the first Frankfurt-New York crossing of the season. Herb Morrison was actually recording a live radio commentary; here are his words as the drama unfolded:

The ship is riding majestically towards us, riding as though it is mighty proud of the place it is playing in the world's aviation…There's smoke and there's flames now…crashing into the ground – not quite to the mooring mast. This is terrible. This is one of the worst catastrophes in the world…Oh, the humanity! And all the people are screaming around here…I don't believe it…I can't even talk to people. Their friends are out there…I'm going to have to stop.

(Christopher, 131)

35 people on board (13 passengers and 22 crew) and one member of the ground crew died in the disaster. 62 people survived. Some people miraculously stepped off the airship and escaped without a scratch. One elderly lady actually descended via the usual exit ladder, while Werner Franz, a cabin boy, was saved because he was drenched by a burst water ballast tank. Eugen Bentele, a mechanic, was thrown clear of one of the engine ports and survived with only minor burns. Three children were thrown by their mother to be caught by the ground crew. Others were not so lucky and, trapped in the blazing mesh of metal, died a horrible death. Many survivors were badly burned. Captain Pruss was seriously injured but survived. Ernst Lehmann, Director of Zeppelin operations, was on board, and, badly burned, he succumbed to his wounds the next day.

The origin of the fire that destroyed the Hindenburg remains a mystery, but there has been much speculation as to what might have been the cause. Official inquiries were conducted by the United States and Germany, but all that was agreed upon was that the fire had begun at the rear of the airship and the hydrogen cells had been highly combustible. It was speculated that the initial spark that caused the fire may have been caused by a metal cable snapping – the airship did make a sharp turn towards the landing rig during its descent – which could then have sliced into a gas cell. Another possibility was that gas leaking from a cell or the gas released as part of the descent procedure was ignited by static in the air following the electrical storm (otherwise known as a brush discharge or St. Elmo's Fire). Lightning alone would likely not have caused the fire since different Zeppelin airships had survived direct lightning strikes in the past. The airship did make a "high" landing rather than the more usual lower landing method, where the airship is brought almost to earth and then pulled by the ground crew to the docking mast. A high landing required a smaller ground crew, but it also meant the airship had a higher electrical potential (the difference between the electrical charge on the ground and the higher storm clouds).

Another theory for the cause of the disaster was the idea that a static charge from the wet ropes lowered to the ground crew had caused the fire. Yet another theory is that the airship's outer paint may have been the culprit. The cotton outer skin of the Hindenburg had been coated with a gelatinous mixture (cellulose acetate butyrate) in order to tighten the fabric, increase waterproofing, and help reflect the heat of direct sunlight. This paint mixture proved to be highly flammable on testing, and it may have been set alight by static electricity in the air. Zeppelin had not used this type of ‘paint' on any other airship.

There was, at the time, and has been ever since the accident, speculation that the fire was an act of sabotage. The fire may have been started by a small timed bomb. This theory captured people's imagination despite the total lack of evidence for any foul play. The only tangible support for such an explanation comes from one surviving crew member who claimed he had seen the first fire appear at the very centre of gas cell number four, an unlikely place if static electricity had been the cause of the fire but a logical location for a bomb, placed where the axial gangway ran all the way through the airship's gas cells.

The bomb theory gained traction largely because many of those who worked for the Zeppelin company, including Lehmann, could not believe an airship would fall from the skies in flames without human intervention. Certainly, the Graf Zeppelin and the Hindenburg had made over 600 flights without ever encountering any serious problems. If the disaster had been caused by sabotage, the question is why? The Hindenburg, with swastikas on its tail fins and a symbol of German success, was an ideal target to strike a propaganda blow against Nazi Germany. Indeed, the Nazis themselves soon peddled a theory that the Hindenburg had been the victim of a Jewish-led plot, again, without any evidence to support such a claim. The Nazis described the Hindenburg's dead crew members as 'soldiers', and their bodies were returned to Germany, where they were given state funerals.

There is no overall consensus as to which of the above theories was the actual cause of the disaster. At the time, it became irrelevant just why the airship had burned to the ground, since the fact that the disaster was caught on film and shown worldwide in newsreels effectively ended air travel using hydrogen-filled airships. The United States would still not consent to selling helium to Germany. The Graf Zeppelin was retired in July 1937, and the new Graf Zeppelin II largely remained within German-Austrian airspace. The German government prohibited hydrogen-filled airships from carrying public passengers. Both airships were dismantled in 1940, and their massive sheds blown up with dynamite on 6 May, three years to the day after the Hindenburg disaster.

Remaining parts of the great Zeppelins, artefacts recovered from the disaster, memorabilia of the period, and a full-scale reconstruction of the Hindenburg's passenger lounge can today be seen at the Zeppelin Museum in Friedrichshafen.