[WalterBright]

> safe tanks of metal

Fuel burns. That's why so much effort is expended in airplanes to try and stop that from happening. The designers learn from experience.

A helium Zeppelin isn't safe from fire, either. Once the canvas catches fire, it's going down in flames. Frankly I doubt whether having hydrogen in it or not makes any real difference. I've seen the clips on the news where hot air balloons, with no hydrogen, catch fire and what happens (everybody dies).

There's no reason to believe that hydrogen Zeppelins could not go through a similar learning process as aircraft that would make them just as safe as airliners are today.