In general you are right, but context is everything. Here is an example where the sentence can be used:
Joe: "I hear you are reading War and Peace. It's such a long novel, when do you have time to read it ?"
Dagny: I read it on the plane to work each day (shorten to I read it on the plane).
As Groucho Mark said, "I once shot an elephant in my pyjamas, how it got in them I'lll never know."