Using Onto and Into
These are old prepositions which are still in common usage. They are both used with verbs that imply some sort of movement or progress.
The plane landed onto the runway.
To land is not a verb which necessarily requires movement; it’s referring to the moment when the plane actually stops on the runway.
The plane landed on the runway.
The plane glided onto the runway.
Gliding most certainly implies motion, so we can use onto with it.
The caterpillar changed in a butterfly.
The caterpillar changed into a butterfly.
Into can usually be replaced by in.
Put the book in the box.
Put the book into the box.
It’s a little more difficult to replace onto with on; it sounds awkward.
We quickly moved the conversation onto a new subject.
We quickly moved the conversation on a new subject.
In English, it can be a little confusing to decide when to use in and when to use on.
I’m in the car; I’ll be home in a minute.
It’s logical to be in a car.
I’m on the bus; I’ll be home in a minute.
I’m on the train; I’ll be home in a minute.
I’m on the plane; I’ll be home in a few hours.