We've all heard about how fog sometimes causes delays to airplanes trying to take off or land but usually, those stories are about the fog being outside of the plane. Well, passengers were a bit alarmed after a thick layer of mist started filling up the cabin of a Delta Flightgoing from Jacksonville, Florida, to John F. Kennedy Airport. One of the passengers filmed the cabin as it was happening and said that there was no odor, but the fog lasted for 30 minutes as the plane sat on the tarmac before takeoff. She said she figured it was related to the humid weather, but wished Delta flight attendants would have explained to passengers what it was. The flight attendants just kept saying this was a practice run for their Halloween haunted house. Passengers weren't amused. Delta said the incident was related to humidity and that it is not required to report it to the Federal Aviation Administration. Check out the video below.