Originally Posted by
Derfred
It might not, but I'd sure as hell rather be standing next to a well-earthed aircraft than a non-earthed aircraft if the lightning ever should unexpectedly strike.
I still might cop a belt, but if the earth cable takes some of the belt, that's less of a belt for me!
The way it tends to work is that at any point in its travel, the lightning bolt will pick the easiest route to ground. Your big danger is that if you're close to the aircraft, it might determine that the easiest route is to jump the air gap between aircraft and you, then go to ground via your feet. The big, friendly ground cable is an attempt to encourage it to follow a known and predictable path.
The biggest danger when near a strike is the ground current as it disperses. The resistance of the earth may mean that two points a metre apart have a 5000V potential difference. This is less of an issue for humans because our feet tend to be a lot closer together, but it takes out a lot of cows if they're in a field and there's a nearby lightning strike.