The Jetpack is an equippable tool that allows the player to fly for as long as the fuel in the Jetpack lasts. Flying is performed by holding down the jump key. It also has a Hover Mode, which can be toggled by pressing the M key. In Hover Mode, holding the jump key will make the player slowly descend, while releasing it will disable the Jetpack, hurling the player downwards at normal fall speed. In Hover Mode, the Jetpack uses less fuel.
There is also an electric version of this tool, the Electric Jetpack.
A fully fueled Jetpack can work for about 90 seconds. When the fuel gauge reaches about 5%, the Jetpack starts losing its power quickly. It can be completely refilled either by 18 Biofuel Cells, or by 6 Coalfuel Cells in a Canning Machine.
If you go high into the air, you will take massive amounts of fall damage, even if you are going very slowly downward, like in Hover Mode. This is because of the minecraft coding itself. Fall damage is calculated by your highest height before your descent. May be fixed in the future. Also applies to the Electric Jetpack.