Can a passenger land the plane?
If your lifelong dream is to heroically land the plane in the event of a major emergency, you could hypothetically carry it out. Newer aircraft are designed for mostly automatic travel, meaning that any amateur can land an updated plane as long as they follow instructions. However, for older planes, this isn't the case.
What are the spirals inside jet engines?
There are spirals inside turbines to make sure that people know when they're rolling or static in order to avoid injury. Regardless, if you're close enough to see the spiral clearly, perhaps you should back up.