The dream: Someday we'll all be flying off to work with personal jet packs strapped to our backs.

The reality: While jet packs exist, a number of factors will probably prevent widespread use. Safety is a major one.

"You crash a jet pack, you die," said Nick MaComber, a jet pack pilot and vice president at Jet Pack International, one of the few companies that builds them.

Fuel is another issue. MaComber's jet pack can fly for a grand total of 30 seconds before it runs out of gas. (He flies it as a spectator event, like at football halftime shows). Adding more fuel makes the thing too heavy, he said. (The water jet pack is a whole other concept - and only works over water.)

Then there's cost -- his was $200,000 to build.

But safety seems like the main issue. "It's a rocket, strapped to your back," said MaComber. Widespread use "is never gonna happen, and it never should."