On July 21, 1919, an American airship, a Type FD Dirigible, owned by Goodyear Tire Company, called the Wingfoot Air Express, caught fire and crashed onto the Illinois Trust and Savings Building. The Hydrogen-filled dirigible was transporting passengers from Grant Park to the White City Amusement Park when the tragedy occurred. Did Goodyear not understand the dangers of using Hydrogen? Were there no other options?
Information about the accident – and many others – at the time, was scarce; there were mostly newspaper and radio reports. Some information was gathered by witnesses and survivors, who had parachuted from the Wingfoot Air Express’s gondola. Any one old enough to remember, let alone participate in any investigation into the Wingfoot Air Express, has since passed away. The only particulars of the event can be summarized as: over the city, the airship suffered a fire near the stern and within seconds the blimp was consumed in flames. The airship buckled at the midpoint, folded and fell from the sky. It was unclear what caused the airship to initially catch fire, but the lifting gas used: Hydrogen, was highly flammable.
Ever since Henry Giffard’s steam-powered airship took flight in 1852, man had moved forward in gaining flight capability; these lighter-than-air blimps (balloons) employed a screw or similar thrust device. The obstructions to success were the inability to steer or control altitude; there was little thought given to the lifting – or buoyant – gas used. In 1884, the La France became the first controllable airship when it returned, through flight, to its starting point. The La France employed a rudder, an elevator, a sliding weight to assist in center of gravity shifts and ballonets, ‘balloons-within-balloons’ that were filled with unbuoyant gas to displace the buoyant gas in the main balloons, envelopes or bags. The use of these devices gave the La France the distinction of being the first Dirigible, a title that comes from the French word diriger, which means “to direct or steer.” The La France also used Hydrogen as a lifting gas; the experiment worked and that was all that mattered. Safety was a blind spot and it prevented one from succeeding. Using Hydrogen suggested airship developers employed a ‘fingers-crossed’ approach.
The Wingfoot Air Express accident’s Root Cause was the use of Hydrogen for buoyancy. Giffard’s airship employed Hydrogen, as did the La France, but neither caught fire nor crashed. The focus in the late 1800s and early 1900s was the successful ability to fly, perhaps by any means possible.
Consider also that at the time of the Wingfoot Air Express accident there were no aviation regulations or policies; the aviation ‘industry’ would soon be placed under the Department of Commerce. Common sense was not referred to because aviation was still in its infancy. Any accident event details relayed between countries that experienced airship accidents were limited by available communications at the time, distance and nations at war. Even information about these events remained elusive due to the lack of attention they received; controlled flight in the 1800s was an eccentricity.
Was it not known Hydrogen was highly combustible? After all, the three requirements for combustion are (and were) Oxygen, fuel and an ignition source. Would not common sense point out that Hydrogen was a volatile fuel, if used in close proximity to an ignition source? Yes, but the driving force at the time was being the first to master flight; the other guy’s mishap was the other guy’s fault. Competitors attempting to master flight with Hydrogen were like politicians reattempting Socialism: an idea that did not work last time because the other guy did not do it right. A bad idea is still a bad idea.
Common sense did come into play … eventually. One airship tragedy that generated common sense solutions was the Roma, an Italian-made semi-rigid airship, which crashed on February 21, 1922 in Norfolk, Virginia. The Roma was purchased by the United States (US) Army in 1921. Its accident was not the result of the Hydrogen-filled envelopes, instead the rudder system failed, crippling the airship’s maneuverability. However, before it struck the ground, the airship brushed against high voltage power lines; the sparks ignited the Hydrogen-filled envelopes. The Roma became the last US military airship ever inflated with Hydrogen; all subsequent military airships used Helium.
Yet, Hydrogen continued to play a tragic part in airship accidents. The French Navy’s Dixmude (formerly the Zeppelin LZ 114) exploded in mid-air near Sicily after a lightning strike on December 21, 1923. On October 5, 1930, the British airship R101 crashed, then burned, from what was believed to be escaped Hydrogen that ignited. The most infamous Hydrogen-caused Zeppelin accident was the LZ 129 Hindenburg, which burned near its mooring tower in Lakehurst, New Jersey, on May 6, 1937.
The use of Hydrogen as a lifting gas for airships was used predominantly from the 1800s up until the Hindenburg disaster. During World War One (WWI) (1914 – 1918), fighter pilots understood Hydrogen’s volatility. Fighter aircraft, e.g., the Nieuport 17, were equipped with outer wing strut mounted rocket tubes; the electrically triggered rockets were designed to ‘shoot down’ enemy observation balloons and airships using Hydrogen.
Per records, of the thirty-two non-military blimp disasters, eleven were attributed to Hydrogen explosions before the Wingfoot Air Express and another eleven dirigible accidents from the Wingfoot Air Express, up to, and including, the Hindenburg in 1937. By comparison, the other airship accidents were blamed on weather, fueling accidents or other reasons. Yet, Hydrogen’s use was still widespread. Why? From Giffard’s airship through the end of WWI, Hydrogen was the only buoyant gas available, even for military applications.
The only discovered substitute for Hydrogen was Helium, an inert gas that – per the dictionary – “… is not chemically reactive,” meaning it would not explode if introduced to an ignition source. Per the National Academies of Sciences, Engineering and Medicine, the presence of Helium was discovered in 1895 from uranium and thorium ores. In the early 1900s, “… helium was found to exist in rather large quantities in the natural gas wells of the midcontinental United States.” Upon entering WWI, the US opened three helium extraction plants in Texas: two in Fort Worth and one in Petrolia.
Helium was expensive to produce. In 1919, investments permitted the large-scale production of Helium; major production was limited to the US and Canada, allowing the Helium supply to become political. It was believed that countries, such as Germany, who were undergoing political upheavals with the rise of the Third Reich, were denied access to the US’s helium. If this were true, it helps explain why a country as advanced in zeppelin technologies as Germany was, still relied on Hydrogen as a buoyant gas, even in commercial usage – eighteen years after events like the Wingfoot Air Express accident.
The reasons Hydrogen was used as a buoyant gas, despite its dangers, has been discussed here: Hydrogen was the only buoyant gas known at the time; poor communications; warring nations prevented the sharing of information; the need to experiment outweighed safety and Helium had not been available. All these reasons, though factual, had nothing to do with the causes of the individual accidents.
What, then, would have been the Probable Cause of the Wingfoot Air Express accident and what would have been the Recommendations? Since Probable Cause rarely has anything to do with the Root Cause(s) behind any accident, the Probable Cause in a Wingfoot Air Express-type accident could have been an engine that was allowed to operate too hot; the Recommendation would have been to improve engine monitoring methods. A lightning strike; Recommendation: improve meteorological forecasting. Static electricity discharge: Recommendation: prevent static build-up. Cigarette smoking; Recommendation: control where people smoke, which, ironically, the Hindenburg had a smoking room just for this reason.
None of these Recommendations, however, were solutions; they would not have fixed the problem, corrected the Root Cause of the Wingfoot Air Express accident. Engines can operate safely at higher temperatures; lightning exists where rain is not present; every moving airborne object attracts static electricity; many passengers and crew members on passenger dirigibles in the early 1900s, smoked.
The Root Cause, however, would have been specific: the use of Hydrogen as a lifting gas. Contributing factors to the Root Cause could have been expanded to include conditions of combustion, e.g., poor maintenance practices that allowed a gas envelope to leak or poor venting of the envelope area. The Root Cause would have said, no matter what measures were taken to prevent ignition, Hydrogen gas was dangerous to use.
In the end, Wingfoot Air Express caught the attention of the city of Chicago, which updated its aviation safety rules to prevent dirigibles from flying over Chicago. The city’s response was to a Probable Cause mentality; the response did not make aviation safer. Only addressing Root Cause would have improved safety. Anything else was just words on paper.