I am not a teacher, so I don’t know any grammar rules, but I’ll try to explain it, as good as I can.
“von” in this context is more like “from… to …”. (von … nach…)
So you could say:
Mein Sohn fliegt gerade von Norwegen nach Deutschland.
Mein Sohn fliegt gerade aus/von Norwegen zurück. (Without “zurück” it sounds a little bit incomplete, I think.)
I think, you can use both here, unless you are using the combination “von… nach…”. Then you have to use “von”.
(By the way, you successfully confused two native speakers…! ^^)
In my opinion “von” is here more like a starting point. In other cases it can mean “by”.
For example:
This book was written by Stephen King. → Dieses Buch wurde von Stephen King geschrieben.
If I hear “aus” I think someone or something was somewhere inside of something.
For example:
“The cat is in the box.”
“Get the cat out of the box.” → Hol die Katze aus der Box.
This can mean inside a building, city, land, forest and so on.
For example:
He is from New York. → Er kommt aus New York.
I don’t think you can translate “at” as “von” or “aus” at all. I believe it has the same meaning in this sentence as in English. But there are sentences in English where you need to translate “at” with another word than “bei”. A common example are times and dates.
Ich habe diese Hose von bei Kaufhof bekommen.
I googled a little bit. Maybe this is helpful:
If you understand the basic meaning, I would recommend to read more to get used to it. The alternative is to buy a good grammar book. But be careful, some grammar books are written by one linguist for another. Get a sample first or have a look at it at your local book store.