The flying machines were vehicles used by the Kleptons. A flying machine had a large glass bubble-shaped dome for its body, a single seat for the pilot, an antenna on top, wings and a landing base. They could fly both through the air and under water.
In the 30th century, the Kleptons attacked a Thain city in their flying machines, which they used to abduct Thains and cause creepers to destroy many of their buildings. When the First Doctor, John and Gillian arrived, a Klepton flying machine attempted to abduct Gillian, but John threw a brick at it, shattering the dome and causing it to crash. During a second attack, eight flying machines were shot down by the Thains' heat guns, one of which was repaired and used by the time travellers to follow the Kleptons to their underwater city. After they freed the Thain slaves there, they used the flying machines in the airlock to escape and return to the Thain city. (COMIC: The Klepton Parasites)