Jet engine Jet pack : World's first Gas-Turbine backpack. The Bell WR19...

The jetpack really does exist, and flies longer than 20 seconds. But the reality is that it's better to stand on your jet pack than strap it on your back, no matter how cool that seems.
It might just be safer to "basejump" from an engine failure on a Williams X-jet than to have a jetpack fail whilst you are strapped to it