terrorama

I was once in an airplane waiting for departure when they announced that the flight would be delayed due to the wrong fuel being put in the plane. This announcement came after a good while of sitting there already.

We were not allowed off as boarding had been completed. If we got off, we weren't going to be allowed back on.

We sat on the tarmac for two hours, the inside of the plane getting warmer and warmer. It was a goddamn nightmare.

Question(s): How does that happen? What are the different types of fuel and why do they matter? How often does something like that occur?

Thanks!