"I am going to travel by plane."
Translation:Yo voy a viajar en avión.
Can I say: "Voy a viajar POR avion? I thought por was acceptable in this case.
Apparently, many of us said "por." I reported it 19 Nov 2018, so we'll see whether Duo adds it to the database. If not, we'll have our answer.
Why isn't 'el' required before 'avion'? Usually putting a noun without 'la' or 'el' (or 'las' / 'los') in front of it is marked wrong.
I think because we aren't talking about a specific plane but rather as simply a form of transportation.
It would actually be more common I think to just use 'Voy' as there is no ambiguity. Both should be acceptable though.