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)
The Eleventh Doctor gave Alice Obiefune a thought controlled jet pack and the sonic screwdriver to aid her in a search of the Amstron's sacred library for a book on the Eternal Dogfight. (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)