A jetpack or rocket pack (also spelled "jet pack" or "jet-pack") was a device worn on the back, propelled by rocket engines, allowing a user to propel themselves into the air and fly.
Several such devices were owned by the Doctor. John and Gillian used jetpacks to rescue the First Doctor on Zerox. (COMIC: The Hunters of Zerox) The Second Doctor used his rocket pack to eject himself from a crashing airplaine. (COMIC: The Faithful Rocket Pack)
Amstrons used thought controlled jet packs to travel within the Great Wheel. The Eleventh Doctor, John Jones and ARC used them to get to Amstron sacred library. (COMIC: The Eternal Dogfight) Later Alice Obiefune used one to search books in the library. (COMIC: The Infinite Astronaut)
When the Eleventh Doctor attended a football game at the Leadworth Football Club, he was bored by the match because it lacked jetpacks and there were no women on the teams. (COMIC: Bow-ties for Goal Posts)
On the planet Unnamed BX-4, the Twelfth Doctor, Clara Oswald, Mr Hitch, Mr Wiremu and Gela all used jetpacks to escape being fired at by the Hadax Ura. The Doctor later used a jetpack to get back to the lander to stop the Hadax Ura from escaping the planet. (COMIC: Spirits of the Jungle)