Over the years, many hypotheses about how the fire aboard the Hindenburg started have been proposed. One of the more popular theories in conspiracy theory circles is that the airship was sabotaged, by anyone from communists to Adolf Hitler. This week, a new documentary on the disaster will endorse one of the more mainstream explanations for the explosion.

According to a report by The Independent, the new documentary, to air Thursday on the U.K.’s Channel 4, states that static electricity may have set the zeppelin ablaze. In this scenario, an electrical storm had charged the airship while gas had somehow leaked into the Hindenburg’s ventilation shafts. Crew members who took up the zeppelin’s landing ropes may have grounded the ship’s frame, but not its skin, causing the spark that set off the fire at the tail end of the ship.

According to the Independent, a group of experts led by aeronautical engineer Jem Stansfield set fire to quite a few scale models of the Hindenburg before reaching this conclusion. The research team recreated different scenarios for the disaster using the replicas, and tested multiple theories, including sabotage.

The Hindenburg, a German passenger airship, caught fire on May 6, 1937 over an airfield at the Lakehurst Naval Airstation in New Jersey. The blaze took down the airship in under 20 seconds, causing the deaths of 35 of the 97 people on board the ship. Newsreel footage of the disaster, featuring commentary from radio reporter Herbert Morrison, has become famous and is the origin of the popularization of the phrase, “oh the humanity!”