Amelia is actually based on aeronaut Henry Coxwell, Glaisher’s true co-balloon pilot . Coxwell became a professional aeronaut in 1848, and made many trips all over the world. In 1862, Glaisher sought him out so that the British Association for the Advancement of Science could study the weather and atmosphere, as well as the possibility of forecasting the weather (yup, there was a time you couldn’t look at your phone’s weather app). Although the trailer shows us a glimpse of it happening, Glaisher really did pass out and his final barometer reading before doing so was an altitude of 29,000 ft. Coxwell apparently couldn’t feel his hands by the end of their journey, but was able to save them both by pulling the valve-cord with his teeth like a total badass (this allowed the balloon to descend and get them safely to land). It was later calculated that they reached somewhere between 35,000 and 37,000 feet in the sky.