In is always used for location with a few exceptions. One of the main exceptions you will find in common, everyday English is when you are using public transit. When traveling by bus, train, or plane, for instance, you will use "on" instead of "in"
Examples:
I am on a plane.
I am on a train.
I am on a bus.
using "on" in these examples suggest that you are in motion, and using the vehicles for traveling from point A to point B.
Hope this helped :)