system
Given the following post, respond as if you're commenting on Reddit:
human
ELIF- How does a hot air balloon work? How does the pilot know where they're going to end up and what happens if it all goes wrong?
gpt
Controlling a hot air ballon is a lot of guesswork. Educated guesswork, but guesswork nonetheless.

By controlling the heat inside the actual ballon (this is done using gas burners) it's possible to control if the ballon is rising (because it's hotter than the surrounding air) or declining (because it's colder, respectively.).

The ballon also has a valve at the top where you can let hot air out, to speed up the process of cooling down.

And that is really all there is to it. Hot ballon goes up. Cold ballon goes down.

Actual navigation, though, takes skill. A ballon is always and indefinitely moving in the direction the wind is blowing. Which means that if you want to go west, you'll have to wait until you have wind blowing towards the west.

Complicating things a bit, wind can blow in different directions at different heights. Which means that you can go higher and find a patch of wind going in sort of the right direction instead of staying low and going in the exact opposite direction.

The easiest way to find out exactly how the wind is blowing above you is to release a small helium ballon (because helium ballons always go up) and see in which direction it goes when the wind grabs hold of it.

The rest is all about skill. Knowledge. A tour ballon pilot would typically have several pre-planned routes to choose from depending on wind direction. "If the wind is blowing westward, we'll have to start east of the national park with all the wild animals. And land someplace west of it." The problem is the "someplace" bit, because you don't necessarily end up where you intended to.

Most aircraft can fend for themselves and force a direction they want with a propeller, but an air ballon just...can't. So, to simplify things for everyone, air ballons got their own set of aviation rules where other aircraft has to make way for them. The obvious issue here is of course that ballons are not necessarily welcome in any airspace, because the extra considerations everyone else has to make for them.

Things that typically go wrong is that the wind changes at the exact worst thinkable time, pushing the ballon towards a high voltage power line. Or, you know, towards a forest. Or a cliffside. Any place where you can't immediately land is a risk that the pilot would try to avoid. Passing a risk area means that they have to plan ahead.

When all you can control is height, you'll have to go higher. Because if you can only go up, then you are soon out of options. But if you can also go down, then you got two options to choose from.

What happens when the ballon risks running into a power line is that the pilot has to consider the two options. 1) burn gas and get more heat so that the ballon slowly rises? 2) release hot air so that the ballon quickly goes down?

Going down is always easy. Going down comfortably, thats more difficult. Going down comfortably when you are in a hurry, When you desperately have to come down immediately, that takes skill. And could definitely involve bruises as a calculated better outcome.